Unable to write to JSONB column

Hi! Having the same issue as #432.

Can not insert value to a table with jsonb column (tried json also). Insert code looks like this:

await _db.RequestLogs.InsertAsync(() =>
                new RequestLog
                {
                    RequestBody = JsonConvert.SerializeObject(requestBody),
                });

pg logs:

2019-01-13 17:44:35.723 MSK [16200] ERROR:  42804: column "request_body" is of type jsonb but expression is of type text at character 129
2019-01-13 17:44:35.723 MSK [16200] STATEMENT:  INSERT INTO clear_junction.request_log
	(
		request_body
	)
	VALUES
	(
		$1,
	)

Interesting, that it is ok to insert with constant:

await _db.RequestLogs.InsertAsync(() =>
                new RequestLog
                {
                    RequestBody = "{""Body"": ""body value""}",
                });

linq2db version: 2.6.1 Database Server: PostgreSQL 11.1 Database Provider: Npgsql 4.0.4 Operating system: Windows 10 Framework version: .NET Core 2.1

[MaceWindu]

Actually it should work with strings. Make sure your column attribute has DataType = DataType.BinaryJson property

[MaceWindu]

Also if you use T4 to generate your mappings, set GenerateDataTypes=true; so DataType property will be generated for you