Encoding map objects to string during escaping process

[michael-borisov]

Encoding of incoming data in map format to JSON to prevent an error like those below

** (FunctionClauseError) no function clause matching in Clickhousex.Codec.Values.to_iodata/4
    (clickhousex 0.4.0) lib/clickhousex/codec/values.ex:120: Clickhousex.Codec.Values.to_iodata(%{"key" => "value"}, 0, %{"key" => "value"}, [])
    (clickhousex 0.4.0) lib/clickhousex/codec/values.ex:104: Clickhousex.Codec.Values.encode_param/2
    (clickhousex 0.4.0) lib/clickhousex/codec/values.ex:39: Clickhousex.Codec.Values.weave/4
    (clickhousex 0.4.0) lib/clickhousex/query.ex:53: DBConnection.Query.Clickhousex.Query.encode/3
    (db_connection 2.4.2) lib/db_connection.ex:1255: DBConnection.encode/5
    (db_connection 2.4.2) lib/db_connection.ex:1355: DBConnection.run_prepare_execute/5
    (db_connection 2.4.2) lib/db_connection.ex:1459: DBConnection.run/6
    (db_connection 2.4.2) lib/db_connection.ex:595: DBConnection.parsed_prepare_execute/5
    (db_connection 2.4.2) lib/db_connection.ex:587: DBConnection.prepare_execute/4
    (clickhousex 0.4.0) lib/clickhousex.ex:59: Clickhousex.query/4
    (ecto_sql 3.9.0) lib/ecto/adapters/sql.ex:432: Ecto.Adapters.SQL.query!/4
    (ecto_sql 3.9.0) lib/ecto/adapters/sql.ex:795: Ecto.Adapters.SQL.insert_all/9
    (ecto 3.9.1) lib/ecto/repo/schema.ex:59: Ecto.Repo.Schema.do_insert_all/7
    (stdlib 4.1.1) gen_server.erl:1161: :gen_server.try_terminate/3
    (stdlib 4.1.1) gen_server.erl:1351: :gen_server.terminate/10
    (stdlib 4.1.1) proc_lib.erl:240: :proc_lib.init_p_do_apply/3

It happened when I tried to save data in the JSON field. The Clickhouse supports that as an experimental feature (https://clickhouse.com/docs/en/sql-reference/data-types/json/).

[ruslandoga]

can it be Jason.encode_to_iodata!/1?

[michael-borisov]

Yes! Thank you for the suggestion!

[ruslandoga]

Wouldn't JSON iodata still need to be escaped?

With the current implementation I'm getting

Code: 62. DB::Exception: Cannot parse expression of type Object('json') here: '{\"should\":{\"'\":\"%\",\"\\\\\":\"\",\"_\":\"?\",\"it be\":\"escaped?\"}}'

for a map like

%{"should" => %{"it be" => "escaped?", "_" => "?", "'" => "%", "\\" => ""}}

[ruslandoga]

Sorry for the confusion. I think the previous approach with Jason.encode! is the way to go since escaping iodata seems like too much work.