713 lines
21 KiB
Markdown
713 lines
21 KiB
Markdown
# Exceptions
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## Overview
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### Base type
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All exceptions inherit from class `json::exception` (which in turn inherits from `std::exception`). It is used as the base class for all exceptions thrown by the `basic_json` class. This class can hence be used as "wildcard" to catch exceptions.
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### Switch off exceptions
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Exceptions are used widely within the library. They can, however, be switched off with either using the compiler flag `-fno-exceptions` or by defining the symbol `JSON_NOEXCEPTION`. In this case, exceptions are replaced by `abort()` calls. You can further control this behavior by defining `JSON_THROW_USER` (overriding `#!cpp throw`), `JSON_TRY_USER` (overriding `#!cpp try`), and `JSON_CATCH_USER` (overriding `#!cpp catch`).
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Note that `JSON_THROW_USER` should leave the current scope (e.g., by throwing or aborting), as continuing after it may yield undefined behavior.
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## Parse errors
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This exception is thrown by the library when a parse error occurs. Parse errors
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can occur during the deserialization of JSON text, CBOR, MessagePack, as well
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as when using JSON Patch.
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Exceptions have ids 1xx.
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!!! info "Byte index"
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Member `byte` holds the byte index of the last read character in the input
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file.
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For an input with n bytes, 1 is the index of the first character and n+1
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is the index of the terminating null byte or the end of file. This also
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holds true when reading a byte vector (CBOR or MessagePack).
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### json.exception.parse_error.101
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This error indicates a syntax error while deserializing a JSON text. The error message describes that an unexpected token (character) was encountered, and the member `byte` indicates the error position.
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!!! example
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Input ended prematurely:
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```
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[json.exception.parse_error.101] parse error at 2: unexpected end of input; expected string literal
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```
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No input:
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```
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[json.exception.parse_error.101] parse error at line 1, column 1: syntax error while parsing value - unexpected end of input; expected '[', '{', or a literal
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```
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Control character was not escaped:
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```
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[json.exception.parse_error.101] parse error at line 1, column 2: syntax error while parsing value - invalid string: control character U+0009 (HT) must be escaped to \u0009 or \\; last read: '"<U+0009>'"
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```
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String was not closed:
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```
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[json.exception.parse_error.101] parse error at line 1, column 2: syntax error while parsing value - invalid string: missing closing quote; last read: '"'
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```
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Invalid number format:
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```
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[json.exception.parse_error.101] parse error at line 1, column 3: syntax error while parsing value - invalid number; expected '+', '-', or digit after exponent; last read: '1E'
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```
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`\u` was not be followed by four hex digits:
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```
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[json.exception.parse_error.101] parse error at line 1, column 6: syntax error while parsing value - invalid string: '\u' must be followed by 4 hex digits; last read: '"\u01"'
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```
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Invalid UTF-8 surrogate pair:
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```
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[json.exception.parse_error.101] parse error at line 1, column 13: syntax error while parsing value - invalid string: surrogate U+DC00..U+DFFF must follow U+D800..U+DBFF; last read: '"\uD7FF\uDC00'"
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```
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Invalid UTF-8 byte:
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```
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[json.exception.parse_error.101] parse error at line 3, column 24: syntax error while parsing value - invalid string: ill-formed UTF-8 byte; last read: '"vous \352t'
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```
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!!! tip
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- Make sure the input is correctly read. Try to write the input to standard output to check if, for instance, the input file was successfully openened.
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- Paste the input to a JSON validator like <http://jsonlint.com> or a tool like [jq](https://stedolan.github.io/jq/).
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### json.exception.parse_error.102
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JSON uses the `\uxxxx` format to describe Unicode characters. Code points above above 0xFFFF are split into two `\uxxxx` entries ("surrogate pairs"). This error indicates that the surrogate pair is incomplete or contains an invalid code point.
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!!! example
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```
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parse error at 14: missing or wrong low surrogate
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```
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### json.exception.parse_error.103
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Unicode supports code points up to 0x10FFFF. Code points above 0x10FFFF are invalid.
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!!! example
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```
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parse error: code points above 0x10FFFF are invalid
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```
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### json.exception.parse_error.104
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[RFC 6902](https://tools.ietf.org/html/rfc6902) requires a JSON Patch document to be a JSON document that represents an array of objects.
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!!! example
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```
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[json.exception.parse_error.104] parse error: JSON patch must be an array of objects
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```
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### json.exception.parse_error.105
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An operation of a JSON Patch document must contain exactly one "op" member, whose value indicates the operation to perform. Its value must be one of "add", "remove", "replace", "move", "copy", or "test"; other values are errors.
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!!! example
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```
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[json.exception.parse_error.105] parse error: operation 'add' must have member 'value'
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```
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```
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[json.exception.parse_error.105] parse error: operation 'copy' must have string member 'from'
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```
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```
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[json.exception.parse_error.105] parse error: operation value 'foo' is invalid
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```
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### json.exception.parse_error.106
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An array index in a JSON Pointer ([RFC 6901](https://tools.ietf.org/html/rfc6901)) may be `0` or any number without a leading `0`.
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!!! example
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```
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[json.exception.parse_error.106] parse error: array index '01' must not begin with '0'
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```
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### json.exception.parse_error.107
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A JSON Pointer must be a Unicode string containing a sequence of zero or more reference tokens, each prefixed by a `/` character.
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!!! example
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```
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[json.exception.parse_error.107] parse error at byte 1: JSON pointer must be empty or begin with '/' - was: 'foo'
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```
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### json.exception.parse_error.108
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In a JSON Pointer, only `~0` and `~1` are valid escape sequences.
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!!! example
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```
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[json.exception.parse_error.108] parse error: escape character '~' must be followed with '0' or '1'
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```
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### json.exception.parse_error.109
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A JSON Pointer array index must be a number.
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!!! example
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```
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[json.exception.parse_error.109] parse error: array index 'one' is not a number
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```
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```
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[json.exception.parse_error.109] parse error: array index '+1' is not a number
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```
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### json.exception.parse_error.110
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When parsing CBOR or MessagePack, the byte vector ends before the complete value has been read.
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!!! example
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```
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[json.exception.parse_error.110] parse error at byte 5: syntax error while parsing CBOR string: unexpected end of input
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```
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```
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[json.exception.parse_error.110] parse error at byte 2: syntax error while parsing UBJSON value: expected end of input; last byte: 0x5A
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```
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### json.exception.parse_error.112
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Not all types of CBOR or MessagePack are supported. This exception occurs if an unsupported byte was read.
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!!! example
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```
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[json.exception.parse_error.112] parse error at byte 1: syntax error while parsing CBOR value: invalid byte: 0x1C
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```
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### json.exception.parse_error.113
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While parsing a map key, a value that is not a string has been read.
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!!! example
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```
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[json.exception.parse_error.113] parse error at byte 2: syntax error while parsing CBOR string: expected length specification (0x60-0x7B) or indefinite string type (0x7F); last byte: 0xFF
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```
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```
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[json.exception.parse_error.113] parse error at byte 2: syntax error while parsing MessagePack string: expected length specification (0xA0-0xBF, 0xD9-0xDB); last byte: 0xFF
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```
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```
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[json.exception.parse_error.113] parse error at byte 2: syntax error while parsing UBJSON char: byte after 'C' must be in range 0x00..0x7F; last byte: 0x82
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```
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### json.exception.parse_error.114
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The parsing of the corresponding BSON record type is not implemented (yet).
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!!! example
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```
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[json.exception.parse_error.114] parse error at byte 5: Unsupported BSON record type 0xFF
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```
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## Iterator errors
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This exception is thrown if iterators passed to a library function do not match
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the expected semantics.
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Exceptions have ids 2xx.
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### json.exception.invalid_iterator.201
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The iterators passed to constructor `basic_json(InputIT first, InputIT last)` are not compatible, meaning they do not belong to the same container. Therefore, the range (`first`, `last`) is invalid.
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!!! example
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```
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[json.exception.invalid_iterator.201] iterators are not compatible
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```
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### json.exception.invalid_iterator.202
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In an erase or insert function, the passed iterator @a pos does not belong to the JSON value for which the function was called. It hence does not define a valid position for the deletion/insertion.
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!!! example
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```
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[json.exception.invalid_iterator.202] iterator does not fit current value
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```
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```
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[json.exception.invalid_iterator.202] iterators first and last must point to objects
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```
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### json.exception.invalid_iterator.203
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Either iterator passed to function `erase(IteratorType` first, IteratorType last) does not belong to the JSON value from which values shall be erased. It hence does not define a valid range to delete values from.
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!!! example
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```
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[json.exception.invalid_iterator.203] iterators do not fit current value
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```
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### json.exception.invalid_iterator.204
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When an iterator range for a primitive type (number, boolean, or string) is passed to a constructor or an erase function, this range has to be exactly (`begin(),` `end()),` because this is the only way the single stored value is expressed. All other ranges are invalid.
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!!! example
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```
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[json.exception.invalid_iterator.204] iterators out of range
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```
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### json.exception.invalid_iterator.205
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When an iterator for a primitive type (number, boolean, or string) is passed to an erase function, the iterator has to be the `begin()` iterator, because it is the only way to address the stored value. All other iterators are invalid.
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!!! example
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```
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[json.exception.invalid_iterator.205] iterator out of range
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```
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### json.exception.invalid_iterator.206
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The iterators passed to constructor `basic_json(InputIT first, InputIT last)` belong to a JSON null value and hence to not define a valid range.
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!!! example
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```
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[json.exception.invalid_iterator.206] cannot construct with iterators from null
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```
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### json.exception.invalid_iterator.207
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The `key()` member function can only be used on iterators belonging to a JSON object, because other types do not have a concept of a key.
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!!! example
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```
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[json.exception.invalid_iterator.207] cannot use key() for non-object iterators
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```
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### json.exception.invalid_iterator.208
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The `operator[]` to specify a concrete offset cannot be used on iterators belonging to a JSON object, because JSON objects are unordered.
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!!! example
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```
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[json.exception.invalid_iterator.208] cannot use operator[] for object iterators
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```
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### json.exception.invalid_iterator.209
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The offset operators (`+`, `-`, `+=`, `-=`) cannot be used on iterators belonging to a JSON object, because JSON objects are unordered.
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!!! example
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```
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[json.exception.invalid_iterator.209] cannot use offsets with object iterators
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```
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### json.exception.invalid_iterator.210
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The iterator range passed to the insert function are not compatible, meaning they do not belong to the same container. Therefore, the range (`first`, `last`) is invalid.
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!!! example
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```
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[json.exception.invalid_iterator.210] iterators do not fit
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```
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### json.exception.invalid_iterator.211
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The iterator range passed to the insert function must not be a subrange of the container to insert to.
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!!! example
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```
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[json.exception.invalid_iterator.211] passed iterators may not belong to container
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```
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### json.exception.invalid_iterator.212
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When two iterators are compared, they must belong to the same container.
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!!! example
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```
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[json.exception.invalid_iterator.212] cannot compare iterators of different containers
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```
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### json.exception.invalid_iterator.213
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The order of object iterators cannot be compared, because JSON objects are unordered.
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!!! example
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```
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[json.exception.invalid_iterator.213] cannot compare order of object iterators
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```
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### json.exception.invalid_iterator.214
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Cannot get value for iterator: Either the iterator belongs to a null value or it is an iterator to a primitive type (number, boolean, or string), but the iterator is different to `begin()`.
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!!! example
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```
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[json.exception.invalid_iterator.214] cannot get value
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```
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## Type errors
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This exception is thrown in case of a type error; that is, a library function is executed on a JSON value whose type does not match the expected semantics.
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Exceptions have ids 3xx.
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### json.exception.type_error.301
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To create an object from an initializer list, the initializer list must consist only of a list of pairs whose first element is a string. When this constraint is violated, an array is created instead.
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!!! example
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```
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[json.exception.type_error.301] cannot create object from initializer list
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```
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### json.exception.type_error.302
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During implicit or explicit value conversion, the JSON type must be compatible to the target type. For instance, a JSON string can only be converted into string types, but not into numbers or boolean types.
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!!! example
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```
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[json.exception.type_error.302] type must be object, but is null
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```
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```
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[json.exception.type_error.302] type must be string, but is object
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```
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### json.exception.type_error.303
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To retrieve a reference to a value stored in a `basic_json` object with `get_ref`, the type of the reference must match the value type. For instance, for a JSON array, the `ReferenceType` must be `array_t &`.
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!!! example
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```
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[json.exception.type_error.303] incompatible ReferenceType for get_ref, actual type is object
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```
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```
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[json.exception.type_error.303] incompatible ReferenceType for get_ref, actual type is number"
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```
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### json.exception.type_error.304
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The `at()` member functions can only be executed for certain JSON types.
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!!! example
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```
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[json.exception.type_error.304] cannot use at() with string
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```
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```
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[json.exception.type_error.304] cannot use at() with number
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```
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### json.exception.type_error.305
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The `operator[]` member functions can only be executed for certain JSON types.
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!!! example
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```
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[json.exception.type_error.305] cannot use operator[] with a string argument with array
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```
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```
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[json.exception.type_error.305] cannot use operator[] with a numeric argument with object
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```
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### json.exception.type_error.306
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The `value()` member functions can only be executed for certain JSON types.
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!!! example
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```
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[json.exception.type_error.306] cannot use value() with number
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```
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### json.exception.type_error.307
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The `erase()` member functions can only be executed for certain JSON types.
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!!! example
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```
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[json.exception.type_error.307] cannot use erase() with string
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```
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### json.exception.type_error.308
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The `push_back()` and `operator+=` member functions can only be executed for certain JSON types.
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!!! example
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```
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[json.exception.type_error.308] cannot use push_back() with string
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```
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### json.exception.type_error.309
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The `insert()` member functions can only be executed for certain JSON types.
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!!! example
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```
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[json.exception.type_error.309] cannot use insert() with array
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```
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```
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[json.exception.type_error.309] cannot use insert() with number
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```
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### json.exception.type_error.310
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The `swap()` member functions can only be executed for certain JSON types.
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!!! example
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```
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[json.exception.type_error.310] cannot use swap() with number
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```
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### json.exception.type_error.311
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The `emplace()` and `emplace_back()` member functions can only be executed for certain JSON types.
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!!! example
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```
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[json.exception.type_error.311] cannot use emplace() with number
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```
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```
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[json.exception.type_error.311] cannot use emplace_back() with number
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```
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### json.exception.type_error.312
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The `update()` member functions can only be executed for certain JSON types.
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!!! example
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```
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[json.exception.type_error.312] cannot use update() with array
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```
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### json.exception.type_error.313
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The `unflatten` function converts an object whose keys are JSON Pointers back into an arbitrary nested JSON value. The JSON Pointers must not overlap, because then the resulting value would not be well defined.
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!!! example
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```
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[json.exception.type_error.313] invalid value to unflatten
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```
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### json.exception.type_error.314
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The `unflatten` function only works for an object whose keys are JSON Pointers.
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!!! example
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Calling `unflatten()` on an array `#!json [1,2,3]`:
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```
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[json.exception.type_error.314] only objects can be unflattened
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```
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### json.exception.type_error.315
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The `unflatten()` function only works for an object whose keys are JSON Pointers and whose values are primitive.
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!!! example
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Calling `unflatten()` on an object `#!json {"/1", [1,2,3]}`:
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```
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[json.exception.type_error.315] values in object must be primitive
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```
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### json.exception.type_error.316
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The `dump()` function only works with UTF-8 encoded strings; that is, if you assign a `std::string` to a JSON value, make sure it is UTF-8 encoded.
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!!! example
|
|
|
|
Calling `dump()` on a JSON value containing an ISO 8859-1 encoded string:
|
|
```
|
|
[json.exception.type_error.316] invalid UTF-8 byte at index 15: 0x6F
|
|
```
|
|
|
|
!!! tip
|
|
|
|
- Store the source file with UTF-8 encoding.
|
|
- Pass an error handler as last parameter to the `dump()` function to avoid this exception:
|
|
- `json::error_handler_t::replace` will replace invalid bytes sequences with `U+FFFD`
|
|
- `json::error_handler_t::ignore` will silently ignore invalid byte sequences
|
|
|
|
### json.exception.type_error.317
|
|
|
|
The dynamic type of the object cannot be represented in the requested serialization format (e.g. a raw `true` or `null` JSON object cannot be serialized to BSON)
|
|
|
|
!!! example
|
|
|
|
Serializing `#!json null` to BSON:
|
|
```
|
|
[json.exception.type_error.317] to serialize to BSON, top-level type must be object, but is null
|
|
```
|
|
Serializing `#!json [1,2,3]` to BSON:
|
|
```
|
|
[json.exception.type_error.317] to serialize to BSON, top-level type must be object, but is array
|
|
```
|
|
|
|
!!! tip
|
|
|
|
Encapsulate the JSON value in an object. That is, instead of serializing `#!json true`, serialize `#!json {"value": true}`
|
|
|
|
|
|
## Out of range
|
|
|
|
This exception is thrown in case a library function is called on an input parameter that exceeds the expected range, for instance in case of array indices or nonexisting object keys.
|
|
|
|
Exceptions have ids 4xx.
|
|
|
|
|
|
### json.exception.out_of_range.401
|
|
|
|
The provided array index `i` is larger than `size-1`.
|
|
|
|
!!! example
|
|
|
|
```
|
|
array index 3 is out of range
|
|
```
|
|
|
|
### json.exception.out_of_range.402
|
|
|
|
The special array index `-` in a JSON Pointer never describes a valid element of the array, but the index past the end. That is, it can only be used to add elements at this position, but not to read it.
|
|
|
|
!!! example
|
|
|
|
```
|
|
array index '-' (3) is out of range
|
|
```
|
|
|
|
### json.exception.out_of_range.403
|
|
|
|
The provided key was not found in the JSON object.
|
|
|
|
!!! example
|
|
|
|
```
|
|
key 'foo' not found
|
|
```
|
|
|
|
### json.exception.out_of_range.404
|
|
|
|
A reference token in a JSON Pointer could not be resolved.
|
|
|
|
!!! example
|
|
|
|
```
|
|
unresolved reference token 'foo'
|
|
```
|
|
|
|
### json.exception.out_of_range.405
|
|
|
|
The JSON Patch operations 'remove' and 'add' can not be applied to the root element of the JSON value.
|
|
|
|
!!! example
|
|
|
|
```
|
|
JSON pointer has no parent
|
|
```
|
|
|
|
### json.exception.out_of_range.406
|
|
|
|
A parsed number could not be stored as without changing it to NaN or INF.
|
|
|
|
!!! example
|
|
|
|
```
|
|
number overflow parsing '10E1000'
|
|
```
|
|
|
|
### json.exception.out_of_range.407
|
|
|
|
UBJSON and BSON only support integer numbers up to 9223372036854775807.
|
|
|
|
!!! example
|
|
|
|
```
|
|
number overflow serializing '9223372036854775808'
|
|
```
|
|
|
|
### json.exception.out_of_range.408
|
|
|
|
The size (following `#`) of an UBJSON array or object exceeds the maximal capacity.
|
|
|
|
!!! example
|
|
|
|
```
|
|
excessive array size: 8658170730974374167
|
|
```
|
|
|
|
### json.exception.out_of_range.409
|
|
|
|
Key identifiers to be serialized to BSON cannot contain code point U+0000, since the key is stored as zero-terminated c-string.
|
|
|
|
!!! example
|
|
|
|
```
|
|
BSON key cannot contain code point U+0000 (at byte 2)
|
|
```
|
|
|
|
## Further exceptions
|
|
|
|
This exception is thrown in case of errors that cannot be classified with the
|
|
other exception types.
|
|
|
|
Exceptions have ids 5xx.
|
|
|
|
### json.exception.other_error.501
|
|
|
|
A JSON Patch operation 'test' failed. The unsuccessful operation is also printed.
|
|
|
|
!!! example
|
|
|
|
Executing `#!json {"op":"test", "path":"/baz", "value":"bar"}` on `#!json {"baz": "qux"}`:
|
|
|
|
```
|
|
[json.exception.other_error.501] unsuccessful: {"op":"test","path":"/baz","value":"bar"}
|
|
```
|