33 lines
978 B
Markdown
33 lines
978 B
Markdown
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# Access with default value: value
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## Overview
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In many situations such as configuration files, missing values are not exceptional, but may be treated as if a default value was present.
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??? example
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Consider the following JSON value:
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```json
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{
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"logOutput": "result.log",
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"append": true
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}
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```
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Assume the value is parsed to a `json` variable `j`.
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| expression | value |
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| ---------- | ----- |
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| `#!cpp j` | `#!json {"logOutput": "result.log", "append": true}` |
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| `#!cpp j.value("logOutput", "logfile.log")` | `#!json "result.log"` |
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| `#!cpp j.value("append", true)` | `#!json true` |
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| `#!cpp j.value("append", false)` | `#!json true` |
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| `#!cpp j.value("logLevel", "verbose")` | `#!json "verbose"` |
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## Note
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!!! failure "Exceptions"
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- `value` can only be used with objects. For other types, a [`basic_json::type_error`](../../home/exceptions.md#jsonexceptiontype_error306) is thrown.
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