json/doc/mkdocs/docs/api/basic_json/merge_patch.md

basic_json::merge_patch

void merge_patch(const basic_json& apply_patch);

The merge patch format is primarily intended for use with the HTTP PATCH method as a means of describing a set of modifications to a target resource's content. This function applies a merge patch to the current JSON value.

The function implements the following algorithm from Section 2 of RFC 7396 (JSON Merge Patch):

define MergePatch(Target, Patch):
  if Patch is an Object:
    if Target is not an Object:
      Target = {} // Ignore the contents and set it to an empty Object
    for each Name/Value pair in Patch:
      if Value is null:
        if Name exists in Target:
          remove the Name/Value pair from Target
      else:
        Target[Name] = MergePatch(Target[Name], Value)
    return Target
  else:
    return Patch

Thereby, Target is the current object; that is, the patch is applied to the current value.

Parameters

apply_patch (in)

the patch to apply

Complexity

Linear in the lengths of apply_patch.

Example

??? example

The following code shows how a JSON Merge Patch is applied to a JSON document.
 
```cpp
--8<-- "examples/merge_patch.cpp"
```

Output:

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

Version history

• Added in version 3.0.0.