basic_json::patch

basic_json patch(const basic_json& json_patch) const;

JSON Patch defines a JSON document structure for expressing a sequence of operations to apply to a JSON) document. With this function, a JSON Patch is applied to the current JSON value by executing all operations from the patch.

Parameters

json_patch (in): JSON patch document

Return value

patched document

Exceptions

Throws parse_error.104 if the JSON patch does not consist of an array of objects.
Throws parse_error.105 if the JSON patch is malformed (e.g., mandatory attributes are missing); example: "operation add must have member path".
Throws out_of_range.401 if an array index is out of range.
Throws out_of_range.403 if a JSON pointer inside the patch could not be resolved successfully in the current JSON value; example: "key baz not found".
Throws out_of_range.405 if JSON pointer has no parent ("add", "remove", "move")
Throws out_of_range.501 if "test" operation was unsuccessful.

Exception safety

Strong guarantee: if an exception is thrown, there are no changes in the JSON value.

Complexity

Linear in the size of the JSON value and the length of the JSON patch. As usually only a fraction of the JSON value is affected by the patch, the complexity can usually be neglected.

Note

The application of a patch is atomic: Either all operations succeed and the patched document is returned or an exception is thrown. In any case, the original value is not changed: the patch is applied to a copy of the value.

Example

??? example

The following code shows how a JSON patch is applied to a value.
 
```cpp
--8<-- "examples/patch.cpp"
```

Output:

```json
--8<-- "examples/patch.output"
```

Version history

Added in version 2.0.0.

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