JSON: Set Value¶
Sets a value inside JSON data using a dot-separated key path. Supports navigating objects and arrays (using numeric indices for arrays) and creates intermediate objects/arrays as needed. If the key path is empty, the entire data is replaced with the provided value.
Usage¶
Use this node when you need to insert or update a value within nested JSON data by specifying a path like user.profile.name or items.0.title. It accepts JSON data as a dict/list or a JSON string. Typically used after parsing JSON, or before serializing back to a string, to programmatically modify specific fields.
Inputs¶
| Field | Required | Type | Description | Example |
|---|---|---|---|---|
| json_data | True | WILDCARD | The JSON data to modify. Can be a dict, list, or a JSON string. If a string is provided, it will be parsed. | {'user': {'name': 'Alice'}, 'items': [{'title': 'Old'}]} |
| key_path | True | STRING | Dot-separated path to where the value should be set. Use numeric segments to index into arrays (e.g., items.0.title). Leave empty to replace the entire input with the provided value. | items.0.title |
| value | True | WILDCARD | The value to set at the specified path. Can be any JSON-serializable type. | New Title |
Outputs¶
| Field | Type | Description | Example |
|---|---|---|---|
| updated_data | WILDCARD | The JSON data after setting the value at the specified path. | {'user': {'name': 'Alice'}, 'items': [{'title': 'New Title'}]} |
Important Notes¶
- Path format: Use dot-separated keys; array indices must be numeric (e.g., items.2.name).
- Empty path: If key_path is empty, the entire output becomes the provided value.
- Input as string: If json_data is a JSON string, it is parsed; if parsing fails or results in null/empty, an empty object {} is used as the base before setting the value.
- Intermediate creation: Missing objects/arrays are created automatically along the path. For arrays, missing indices are filled with {} for intermediate steps and None for final padding.
- Invalid segments: Non-numeric array indices or encountering non-container types in the path will cause the operation to no-op and return the original data.
- Return type: Output is the updated data structure (dict/list/other), not a JSON string.
Troubleshooting¶
- Value not updated: Ensure array path segments are numeric (e.g., '0', '1') and that intermediate path targets are objects/arrays. Invalid segments cause the node to return the original data.
- Output became {} or lost fields: If you passed an invalid JSON string as input, parsing fails and the node starts from an empty object. Validate the JSON first using a JSON validation node or ensure the input string is valid.
- Setting inside arrays behaves unexpectedly: When extending arrays to reach an index, intermediate elements are created. For intermediate steps they are {}, and for final padding they are None; verify your path and expected structure.
- Whole data replaced: This happens when key_path is empty; provide a proper path if you intend to modify only a part of the data.