serde to to turn struct to JSON and insert into text

sample.rs

table! {
    repo_activity_log (id) {
        id -> Integer,
        repo_id -> Integer,
        event -> Text,
        created_at -> Timestamp,
    }
}


#[derive(Debug, PartialEq, FromSqlRow, AsExpression)]
enum RepoEvents {
    LatestCommitOnMaster(Commit)
}

impl ToSql<String, Sqlite> for RepoEvents {
    fn to_sql<W: Write>(&self, out: &mut Output<W, Sqlite>) -> serialize::Result {
        use RepoEvents::*;
        match self {
            LatestCommitOnMaster(commit) => serde_json::ser::to_writer(out, &commit).into()
        }
    }
}

impl FromSql<String, Sqlite> for RepoEvents {
    fn from_sql(bytes: Option<&<Sqlite as Backend>::RawValue>) -> deserialize::Result<Self> {
        if let Some(data) = bytes {
            serde_json::de::from_slice(data.read_blob()).map_err(|e| e.into())
        } else {
            deserialize::Result::Err(bail!("Unable to read RepoEvents from DB"))
        }
    }
}

#[derive(Insertable)]
#[table_name = "repo_activity_log"]
pub struct InsertableRepoEvent {
    repo_id: i32,
    event: RepoEvents,
    created_at: NaiveDateTime,
}

error[E0277]: the trait bound `db::RepoEvents: diesel::Expression` is not satisfied
   --> src/db/mod.rs:109:10
    |
109 | #[derive(Insertable)]
    |          ^^^^^^^^^^ the trait `diesel::Expression` is not implemented for `db::RepoEvents`
    |
    = note: required because of the requirements on the impl of `diesel::expression::AsExpression<diesel::sql_types::Text>` for `db::RepoEvents`

error[E0277]: the trait bound `db::RepoEvents: diesel::Expression` is not satisfied
   --> src/db/mod.rs:109:10
    |
109 | #[derive(Insertable)]
    |          ^^^^^^^^^^ the trait `diesel::Expression` is not implemented for `db::RepoEvents`
    |
    = note: required because of the requirements on the impl of `diesel::Expression` for `&db::RepoEvents`
    = note: required because of the requirements on the impl of `diesel::expression::AsExpression<diesel::sql_types::Text>` for `&db::RepoEvents`

error[E0277]: the trait bound `db::RepoEvents: diesel::Expression` is not satisfied
   --> src/db/mod.rs:109:10
    |
109 | #[derive(Insertable)]
    |          ^^^^^^^^^^ the trait `diesel::Expression` is not implemented for `db::RepoEvents`
    |
    = note: required because of the requirements on the impl of `diesel::Expression` for `&'insert db::RepoEvents`
    = note: required because of the requirements on the impl of `diesel::expression::AsExpression<diesel::sql_types::Text>` for `&'insert db::RepoEvents`

error: aborting due to 3 previous errors