49 lines
1.9 KiB
Markdown
49 lines
1.9 KiB
Markdown
# nlohmann::ordered_json_document
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Defined in header `<nlohmann/json_view.hpp>`
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```
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using ordered_json_document = basic_json_document<ordered_json, view_mode::read_only>;
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```
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This type is a [`basic_json_document`](https://json.nlohmann.me/api/basic_json_document/index.md) of the [`ordered_json`](https://json.nlohmann.me/api/ordered_json/index.md) specialization: [`materialize()`](https://json.nlohmann.me/api/basic_json_view/materialize/index.md) on one of its views preserves the insertion order of object keys, instead of sorting them like [`json_document`](https://json.nlohmann.me/api/json_document/index.md) does.
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## Examples
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Example
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The example below demonstrates how `ordered_json_document` preserves the insertion order of object keys when materializing.
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```
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#include <iostream>
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#include <nlohmann/json_view.hpp>
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using nlohmann::ordered_json_document;
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int main()
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{
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// ordered_json_document is basic_json_document<nlohmann::ordered_json>:
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// materialize() preserves the insertion (source) order of object keys,
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// instead of sorting them like json_document does
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ordered_json_document doc = ordered_json_document::parse(R"({"z": 1, "a": 2, "m": 3})");
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std::cout << doc.root().materialize().dump() << '\n';
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}
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```
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Output:
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```
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{"z":1,"a":2,"m":3}
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```
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## See also
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- [`ordered_json_view`](https://json.nlohmann.me/api/ordered_json_view/index.md) - a view of a value of an `ordered_json_document`
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- [`json_document`](https://json.nlohmann.me/api/json_document/index.md) - the corresponding document for the default `json` specialization
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- [Object Order](https://json.nlohmann.me/features/object_order/index.md) - preserving the insertion order of object keys
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- [Zero-copy JSON views](https://json.nlohmann.me/features/json_view/index.md) - how to parse, inspect and edit a document without building a tree
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## Version history
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Added in version 3.13.0 unreleased.
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