How to diagnose and fix the 2203C sql_json_object_not_found error code in Postgres.

The 2203C error code in PostgreSQL, designated as sql_json_object_not_found, occurs when a JSON object referenced by a JSON path expression cannot be found. This error typically arises when performing operations that require a specific JSON object structure, and the actual JSON data does not contain the object as specified by the path.

Here are some examples and sample code to diagnose and fix this error:

Example 1: Querying Non-Existent JSON Object Key

When querying a JSON object for a key that does not exist, you may trigger this error.

Problematic Query:

SELECT my_json_column->>'non_existent_key' FROM my_table;

Sample Code to Fix:
Ensure that the key exists in the JSON data, or handle the case where the key might not be present.

SELECT COALESCE(my_json_column->>'existing_key', 'default_value') FROM my_table;

Example 2: Using JSON Path Expressions with Incorrect Path

Using a JSON path expression that references a non-existent object or key in the JSON data can cause this error.

Problematic Query:

SELECT jsonb_path_query(my_json_column, '$.nonExistentObject'::jsonpath) FROM my_table;

Sample Code to Fix:
Adjust the JSON path expression to reference an existing object or key.

SELECT jsonb_path_query(my_json_column, '$.existentObject'::jsonpath) FROM my_table;

Example 3: Using SQL/JSON Functions with Incorrect JSON Structure

When using SQL/JSON functions like jsonb_to_record that require a specific JSON structure and the provided JSON does not match, this error can occur.

Problematic Query:

SELECT * FROM jsonb_to_record(my_json_column) AS x(key1 text, key2 text) WHERE my_condition;

Assuming my_json_column does not contain the keys key1 and key2.

Sample Code to Fix:
Make sure the JSON structure matches the expected format by the function.

UPDATE my_table SET my_json_column = '{"key1": "value1", "key2": "value2"}' WHERE my_condition;
-- Then you can run the original query again.

Example 4: Referencing a Non-Existent JSON Object in a Function Argument

Passing a JSON path to a function that expects a certain object, but the object does not exist, can result in this error.

Problematic Query:

SELECT jsonb_insert(my_json_column, '{nonExistentObject, newKey}', '"newValue"') FROM my_table;

Sample Code to Fix:
Ensure the path exists or create the missing object before attempting to insert.

SELECT jsonb_insert(my_json_column, '{}', '{"nonExistentObject": {"newKey": "newValue"}}') FROM my_table;

To diagnose the 2203C error, carefully inspect the JSON data and the JSON path expressions used in the queries. Verify that the JSON structure includes the objects and keys being referenced. If the necessary objects or keys do not exist, you may need to modify the JSON data or adjust the path expressions to align with the actual structure of your JSON.

For more information on working with JSON in PostgreSQL and understanding JSON path expressions, you can refer to the official PostgreSQL documentation.

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