JSON: Set Value¶
Sets a value inside JSON data using a dot-separated key path. Accepts JSON as a Python dict/list or as a JSON string, and will create intermediate objects/arrays as needed along the path. Supports addressing array elements via numeric indices.
Usage¶
Use this node when you need to add or update a specific field deep inside a JSON structure. Common in workflows where you enrich API responses, prepare payloads, or adjust configuration objects dynamically by path. Provide the target JSON, a dot-separated path (including numeric indices for arrays), and the value to set.
Inputs¶
| Field | Required | Type | Description | Example |
|---|---|---|---|---|
| json_data | True | WILDCARD | The JSON to modify. Can be a dict/list object or a valid JSON string. | {"user": {"name": "Alex", "prefs": {}}} |
| key_path | True | STRING | Dot-separated path to the field to set. Use numeric segments to target array indices. | user.prefs.theme |
| value | True | WILDCARD | The value to set at the specified path. Can be any JSON-serializable type (string, number, boolean, null, object, or array). | dark |
Outputs¶
| Field | Type | Description | Example |
|---|---|---|---|
| updated_data | WILDCARD | The JSON data after setting the value at the specified path. | {"user": {"name": "Alex", "prefs": {"theme": "dark"}}} |
Important Notes¶
- Paths: Use dot notation for nested fields (e.g., user.profile.name). Use numeric segments for arrays (e.g., items.0.title).
- String input: If json_data is a string, it must be valid JSON. It will be parsed before modification.
- Empty path: If key_path is empty, the output becomes the provided value (replaces the entire input).
- Intermediate creation: Missing objects/arrays along the path are created automatically. For lists, missing indices are padded.
- Array indices: When setting a final array index beyond current length, the list is extended with nulls until the index exists.
- Type constraints: If a path segment expects a dict but the current value is not a dict (or expects a list index but is not a list), the operation is not applied and the original json_data is returned.
- Invalid array index: Non-numeric array path segments cause the operation to return the original json_data without change.
Troubleshooting¶
- Value not updated: Verify key_path segments match actual types (dict keys vs numeric indices for arrays). If a non-numeric index is used on a list, the node returns the original data.
- Got original data back: The node may have encountered a type mismatch or invalid index. Check each segment of key_path and ensure intermediate structures exist or can be created (objects for keys, arrays for indices).
- Error parsing input: If json_data is a string, ensure it is valid JSON. Invalid JSON prevents parsing and modification.
- Unexpected nulls in arrays: When setting a far index in a list, intermediate positions are filled with null. Adjust the path or pre-size the array if this is undesirable.
- Entire data replaced: If key_path is empty, the node returns the value as the entire output. Provide a non-empty key_path to set a nested field instead.