JSON: Validate¶
Checks whether the provided text is valid JSON. Returns a boolean indicating validity and a companion error message string that is empty when valid and explains the parsing issue when invalid.
Usage¶
Use this node to guard workflows that depend on well-formed JSON. Typical patterns include validating API responses before parsing, verifying user-provided configuration, or gating conditional branches that require valid JSON input.
Inputs¶
| Field | Required | Type | Description | Example |
|---|---|---|---|---|
| json_string | True | STRING | The text to validate as JSON. Multiline input is supported. Accepts any valid JSON type (object, array, string, number, boolean, null). | {"name":"Alice","age":30,"skills":["python","sql"]} |
Outputs¶
| Field | Type | Description | Example |
|---|---|---|---|
| is_valid | BOOLEAN | True if the input is valid JSON; False otherwise. | true |
| error_message | STRING | Empty string when valid; otherwise contains a descriptive parsing error message. | Expecting property name enclosed in double quotes: line 1 column 2 (char 1) |
Important Notes¶
- Syntax-only check: This node validates JSON syntax; it does not enforce schemas or field requirements.
- All JSON types allowed: Objects, arrays, strings, numbers, booleans, and null are valid if properly formatted.
- Empty or whitespace-only input is invalid: Such inputs will return is_valid = False with an error message.
- Error message semantics: When is_valid is True, error_message is an empty string; when False, it contains the parse error.
- Input must be a string: Ensure the value provided is a textual JSON representation, not a pre-parsed structure.
Troubleshooting¶
- Always returns False: Verify the input uses double quotes for keys/strings, has no trailing commas, and is a string. Remove invisible characters (e.g., BOM) or trim whitespace.
- Unexpected characters error: Check for trailing commas, unescaped quotes, or control characters; escape special characters within strings.
- Encoding issues: Ensure the input is UTF-8 encoded text if it contains non-ASCII characters.
- Large JSON inputs: If validation is slow or memory-intensive, reduce the payload size or validate in parts before full processing.