Error
Error Code:
3146
MySQL Error 3146: Invalid JSON Data Type
Description
This error indicates that a MySQL JSON function received an argument that is not a valid JSON string or a native JSON data type. It typically occurs when attempting to perform operations on data that MySQL cannot interpret as JSON, such as plain numbers, booleans, or improperly formatted strings.
Error Message
Invalid data type for JSON data in argument %u to function %s; a JSON string or JSON type is required.
Known Causes
4 known causesNon-JSON Scalar Input
A scalar value (like an integer, boolean, or date) was passed directly to a JSON function that expects a JSON string or JSON data type.
Malformed JSON String
The input provided was intended to be a JSON string, but it contains syntax errors, making it invalid and unrecognizable as JSON by MySQL.
Incorrect Column Data Type
A column with a non-JSON data type (e.g., VARCHAR, TEXT) was used as an argument to a JSON function, but its content was not a valid JSON string.
Improper String Quoting
JSON strings were not properly quoted or escaped within the SQL query, leading MySQL to misinterpret the input.
Solutions
3 solutions available1. Ensure Correct Data Type for JSON Columns easy
Verify that columns intended to store JSON data are declared with the JSON data type.
1
Identify the table and column(s) causing the error. These are likely columns you are attempting to insert or manipulate JSON data into.
2
Check the data type of these columns. If they are not `JSON`, alter the table to change their type.
ALTER TABLE your_table_name MODIFY COLUMN your_json_column_name JSON;3
Re-run the operation that previously failed. If the column was incorrectly defined as a `VARCHAR` or `TEXT`, this will resolve the issue.
2. Validate and Format JSON Data Before Insertion/Update medium
Ensure the data being passed to JSON columns is valid JSON and correctly formatted.
1
Examine the data being inserted or updated into your JSON columns. This might be coming from application code, scripts, or direct SQL statements.
2
Use a JSON validator (online tools or libraries in your programming language) to check if the data conforms to JSON syntax. Common errors include missing commas, incorrect quote usage, or invalid escape sequences.
3
If the data is not valid JSON, correct it. For example, ensure strings within the JSON are properly escaped if they contain quotes.
Example of invalid JSON: {"name": "John"Doe"}
Example of valid JSON: {"name": "John\"Doe"}4
If you are constructing JSON strings in your application code, ensure you are using appropriate JSON serialization functions provided by your language (e.g., `json.dumps()` in Python, `JSON.stringify()` in JavaScript).
5
Re-run the operation with the validated and formatted JSON data.
3. Use MySQL's JSON Functions for Data Manipulation medium
Leverage MySQL's built-in JSON functions to correctly process and store JSON data.
1
When inserting or updating data that needs to be stored as JSON, use MySQL's JSON creation functions like `JSON_OBJECT()` or `JSON_ARRAY()` instead of manual string concatenation.
INSERT INTO your_table_name (your_json_column_name)
VALUES (JSON_OBJECT('key1', 'value1', 'key2', 123));2
If you are extracting data from other columns and want to store it as JSON, use these functions to construct the JSON structure. For example, to create a JSON object from existing columns:
UPDATE your_table_name
SET your_json_column_name = JSON_OBJECT('name', name_column, 'age', age_column)
WHERE some_condition;3
When querying JSON data, use functions like `JSON_EXTRACT()` or the shorthand `->` operator. This ensures you are interacting with the JSON data correctly.
SELECT JSON_EXTRACT(your_json_column_name, '$.key1') FROM your_table_name;4
By using these functions, you delegate the parsing and validation of JSON structures to MySQL, reducing the likelihood of the 'Invalid JSON Data Type' error.