Function json_valid 

pub fn json_valid<J: JsonOrNullableJson + MaybeNullableValue<Bool>, j>(
    j: j,
) -> json_valid<J, j>
where
    j: AsExpression<J>,

Available on crate feature sqlite only.

Returns true if the argument is well-formed JSON, or returns false if is not well-formed.

This function requires at least SQLite 3.46 or newer

Example

let result = diesel::select(json_valid::<Json, _>(json!({"x":35})))
    .get_result::<bool>(connection)?;

assert_eq!(true, result);

let result = diesel::select(json_valid::<Nullable<Json>, _>(None::<serde_json::Value>))
    .get_result::<Option<bool>>(connection)?;

assert_eq!(None, result);