3152
MariaDBERRORNotableJSONHIGH confidence

JSON_TABLE: error processing field

Production Risk

Medium — hard error stops query execution; use NULL ON ERROR in production.

What this means

During JSON_TABLE evaluation, an error occurred when extracting or converting a value from the JSON document for a specific column definition. The column path may not exist or the value cannot be converted to the target type.

Why it happens
  1. 1The JSON path expression does not match any value in the JSON document.
  2. 2The extracted JSON value cannot be coerced to the column type specified in JSON_TABLE.
How to reproduce
trigger — this will error
trigger — this will error
SELECT * FROM JSON_TABLE('{"a": "text"}', '
#x27; COLUMNS(n INT PATH '$.n' ERROR ON ERROR)) AS jt;

expected output

ERROR 3152 (HY000): JSON_TABLE: Got NULL with an error on field '$.n'

Fix 1

Use NULL ON ERROR or DEFAULT ON ERROR

Use NULL ON ERROR or DEFAULT ON ERROR
SELECT * FROM JSON_TABLE('{"a": "text"}', '
#x27; COLUMNS(n INT PATH '$.n' NULL ON ERROR)) AS jt;

Why this works

NULL ON ERROR returns NULL instead of raising an error for missing or unconvertible values.

Fix 2

Validate the JSON structure before querying

Validate the JSON structure before querying
SELECT * FROM t1 WHERE JSON_CONTAINS_PATH(json_col, 'one', '$.n');

Why this works

Pre-filter rows that have the required JSON path.

What not to do

Sources
Official documentation ↗

MySQL 8.0 — 3152 ER_JSON_TABLE_ERROR_ON_FIELD

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