diesel/mysql/types/
json.rs

use crate::deserialize::{self, FromSql};
use crate::mysql::{Mysql, MysqlValue};
use crate::serialize::{self, IsNull, Output, ToSql};
use crate::sql_types;

#[cfg(all(feature = "mysql_backend", feature = "serde_json"))]
impl FromSql<sql_types::Json, Mysql> for serde_json::Value {
    fn from_sql(value: MysqlValue<'_>) -> deserialize::Result<Self> {
        serde_json::from_slice(value.as_bytes()).map_err(|_| "Invalid Json".into())
    }
}

#[cfg(all(feature = "mysql_backend", feature = "serde_json"))]
impl ToSql<sql_types::Json, Mysql> for serde_json::Value {
    fn to_sql<'b>(&'b self, out: &mut Output<'b, '_, Mysql>) -> serialize::Result {
        serde_json::to_writer(out, self)
            .map(|_| IsNull::No)
            .map_err(Into::into)
    }
}

#[test]
fn json_to_sql() {
    use crate::query_builder::bind_collector::ByteWrapper;

    let mut buffer = Vec::new();
    let mut bytes = Output::test(ByteWrapper(&mut buffer));
    let test_json = serde_json::Value::Bool(true);
    ToSql::<sql_types::Json, Mysql>::to_sql(&test_json, &mut bytes).unwrap();
    assert_eq!(buffer, b"true");
}

#[test]
fn some_json_from_sql() {
    use crate::mysql::MysqlType;
    let input_json = b"true";
    let output_json: serde_json::Value = FromSql::<sql_types::Json, Mysql>::from_sql(
        MysqlValue::new_internal(input_json, MysqlType::String),
    )
    .unwrap();
    assert_eq!(output_json, serde_json::Value::Bool(true));
}

#[test]
fn bad_json_from_sql() {
    use crate::mysql::MysqlType;
    let uuid: Result<serde_json::Value, _> = FromSql::<sql_types::Json, Mysql>::from_sql(
        MysqlValue::new_internal(b"boom", MysqlType::String),
    );
    assert_eq!(uuid.unwrap_err().to_string(), "Invalid Json");
}

#[test]
fn no_json_from_sql() {
    let uuid: Result<serde_json::Value, _> =
        FromSql::<sql_types::Json, Mysql>::from_nullable_sql(None);
    assert_eq!(
        uuid.unwrap_err().to_string(),
        "Unexpected null for non-null column"
    );
}
diesel/mysql/types/json.rs

diesel/mysql/types/
json.rs
