Function json_array_length 

pub fn json_array_length<J: JsonOrNullableJsonOrJsonbOrNullableJsonb + MaybeNullableValue<Integer>, j>(
    j: j,
) -> json_array_length<J, j>
where
    j: AsExpression<J>,

Available on crate feature sqlite only.

The json_array_length(X) function returns the number of elements in the JSON array X, or 0 if X is some kind of JSON value other than an array. Errors are thrown if either X is not well-formed JSON or if P is not a well-formed path.

This function requires at least SQLite 3.46 or newer

Example

let result = diesel::select(json_array_length::<Json, _>(json!([1,2,3,4])))
    .get_result::<i32>(connection)?;

assert_eq!(4, result);

let result = diesel::select(json_array_length::<Json, _>(json!({"one":[1,2,3]})))
    .get_result::<i32>(connection)?;

assert_eq!(0, result);

let result = diesel::select(json_array_length::<Nullable<Json>, _>(None::<Value>))
    .get_result::<Option<i32>>(connection)?;

assert_eq!(None, result);

let result = diesel::select(json_array_length::<Jsonb, _>(json!([1,2,3,4])))
    .get_result::<i32>(connection)?;

assert_eq!(4, result);

let result = diesel::select(json_array_length::<Jsonb, _>(json!({"one":[1,2,3]})))
    .get_result::<i32>(connection)?;

assert_eq!(0, result);

let result = diesel::select(json_array_length::<Nullable<Jsonb>, _>(None::<Value>))
    .get_result::<Option<i32>>(connection)?;

assert_eq!(None, result);