basic_json::unflatten

basic_json unflatten() const;

The function restores the arbitrary nesting of a JSON value that has been flattened before using the flatten() function. The JSON value must meet certain constraints:

The value must be an object.
The keys must be JSON pointers (see RFC 6901)
The mapped values must be primitive JSON types.

Return value

the original JSON from a flattened version

Exceptions

The function can throw the following exceptions:

Throws type_error.314 if value is not an object
Throws type_error.315 if object values are not primitive

Exception safety

Strong exception safety: if an exception occurs, the original value stays intact.

Complexity

Linear in the size the JSON value.

Notes

Empty objects and arrays are flattened by flatten() to #!json null values and can not unflattened to their original type. Apart from this example, for a JSON value j, the following is always true: #!cpp j == j.flatten().unflatten().

Example

??? example

The following code shows how a flattened JSON object is unflattened into the original nested JSON object.

```cpp
--8<-- "examples/unflatten.cpp"
```

Output:

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

Version history

Added in version 2.0.0.

1.5 KiB Raw Blame History