SeaQL/sea-orm · error

Failed to get json

Error message

Failed to get json

What it means

This panic comes from `.expect("Failed to get json")` in the sqlx MySQL driver's ProxyRow conversion when a JSON-typed column is decoded into `Option<serde_json::Value>` (behind the `with-json` feature). If sqlx fails to decode the value as JSON -- such as malformed JSON text stored in the column, or a runtime type mismatch -- the expect panics. It indicates the stored value could not be materialized as a serde_json::Value.

Source

Thrown at src/driver/sqlx_mysql.rs:541

                        "DECIMAL" => Value::BigDecimal(
                            row.try_get::<Option<bigdecimal::BigDecimal>, _>(c.ordinal())
                                .expect("Failed to get decimal")
                                .map(Box::new),
                        ),
                        #[cfg(all(
                            feature = "with-rust_decimal",
                            not(feature = "with-bigdecimal")
                        ))]
                        "DECIMAL" => Value::Decimal(
                            row.try_get::<Option<rust_decimal::Decimal>, _>(c.ordinal())
                                .expect("Failed to get decimal")
                                .map(Box::new),
                        ),

                        #[cfg(feature = "with-json")]
                        "JSON" => Value::Json(
                            row.try_get::<Option<serde_json::Value>, _>(c.ordinal())
                                .expect("Failed to get json")
                                .map(Box::new),
                        ),

                        _ => unreachable!("Unknown column type: {}", c.type_info().name()),
                    },
                )
            })
            .collect(),
    }
}

View on GitHub (pinned to e29bcd1b41)

Solutions

1. Validate the stored data: `SELECT col FROM t WHERE JSON_VALID(col) = 0` to find invalid rows, then repair or migrate them.
2. Cast in SQL when the column is not a true JSON type: `CAST(col AS JSON)` or select as TEXT and parse in application code.
3. Ensure the entity column type is Json (with `with-json` enabled) and regenerate entities to match the schema.
4. Align serde_json and sqlx versions in Cargo.lock if a recent upgrade introduced the failure.
5. For mixed legacy data, clean the column with `UPDATE t SET col = JSON_VALID-based fixes` or move invalid rows to a TEXT column.

Example fix

// before
"SELECT meta FROM events"  // meta is LONGTEXT with possibly invalid JSON

// after
"SELECT CAST(meta AS JSON) AS meta FROM events WHERE JSON_VALID(meta)"
// and clean invalid rows first:
"UPDATE events SET meta = '{}' WHERE JSON_VALID(meta) = 0"

// Find rows with invalid JSON before querying:
let bad = db.query_all(Statement::from_string(
    DatabaseBackend::MySql,
    "SELECT id FROM events WHERE meta IS NOT NULL AND JSON_VALID(meta) = 0",
)).await?;
assert!(bad.is_empty(), "invalid JSON stored in events.meta");

When it happens

Trigger: Fetching a MySQL JSON (or TEXT holding JSON) column while `with-json` is enabled and `row.try_get::<Option<serde_json::Value>, _>(c.ordinal())` errors -- typically because the column contains invalid JSON or the sqlx value type is not JSON.

Common situations: Legacy columns typed TEXT/LONGTEXT containing hand-written or truncated JSON; MySQL 5.7/8 JSON columns inserted via non-validating paths; enabling `with-json` after previously storing plain strings; raw SQL proxy queries over JSON columns with sqlx version drift.

Related errors

• Failed to get json
• Not MySQL Connection
• Not MySQL Connection
• Failed to get boolean
• Failed to get unsigned tiny integer

AI-assisted analysis of SeaQL/sea-orm@e29bcd1b41 (2026-09-10). Data as JSON: /api/errors/0626b05f60af030e. Report an issue: GitHub.