Using Where-Clause with predicate causes Npgsql.PostgresException

I’m using linq2db with PostgreSQL 9.6 Target framework 4.5.2 linq2db 1.8.0 npgsql 3.2.2

I got an Npgsql.PostgresException when executing a Select statement using Where-Clause passing a predicate. v1.7.6 works without any errors. Also v1.8.0 works when passing a lambda. Working Sample:

var data = objDB.t_trade_status.Where(y=>y.trade_status_id >= 1 && y.trade_status_id <= 4).ToList();

Exception Sample:

System.Linq.Expressions.Expression<Func<t_trade_status, bool>> predicate = PredicateBuilder.True<t_trade_status>();
predicate= predicate.And(data => data.trade_status_id >= 1);
predicate= predicate.And(data => data.trade_status_id <= 4);
var data = objDB.t_trade_status.Where(predicateOuter).ToList(); -> raised PostgresException (see stacktrace below)

PredicateBuilder is a helper class from http://www.albahari.com/nutshell/predicatebuilder.aspx The database table t_trade_status looks like this:

CREATE TABLE public.t_trade_status
(
  trade_status_id integer NOT NULL DEFAULT nextval('t_trade_status_trade_status_id_seq'::regclass),
  trade_status_name character varying(20) NOT NULL,
  CONSTRAINT trade_status_id_pk PRIMARY KEY (trade_status_id)
)

Stacktrace:

   at Npgsql.NpgsqlConnector.<DoReadMessage>d__147.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.ValueTaskAwaiter`1.GetResult()
   at Npgsql.NpgsqlConnector.<ReadMessage>d__146.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.ValueTaskAwaiter`1.GetResult()
   at Npgsql.NpgsqlConnector.<ReadExpecting>d__153`1.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.ValueTaskAwaiter`1.GetResult()
   at Npgsql.NpgsqlDataReader.<NextResult>d__32.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Npgsql.NpgsqlDataReader.NextResult()
   at Npgsql.NpgsqlCommand.<Execute>d__71.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.ValueTaskAwaiter`1.GetResult()
   at Npgsql.NpgsqlCommand.<ExecuteDbDataReader>d__92.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.ValueTaskAwaiter`1.GetResult()
   at Npgsql.NpgsqlCommand.ExecuteDbDataReader(CommandBehavior behavior)
   at System.Data.Common.DbCommand.System.Data.IDbCommand.ExecuteReader(CommandBehavior behavior)
   at LinqToDB.Data.DataConnection.ExecuteReader(CommandBehavior commandBehavior)
   at LinqToDB.Data.DataConnection.LinqToDB.IDataContext.ExecuteReader(Object query)
   at LinqToDB.Linq.Query`1.<RunQuery>d__11.MoveNext()
   at LinqToDB.Linq.Query`1.<Map>d__69.MoveNext()
   at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
   at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
   at WL.DB.Test.PostgresCRUD.Logging_ReadUserTableViaPredicate() in PostgresCRUD.cs:line 31

And another note: In the exception I see the generated SQL Statement that looks like it’s invalid:

SELECT
	t1.trade_status_id,
	t1.trade_status_name
FROM
	"public".t_trade_status t1
WHERE
	(()) AND t1.trade_status_id >= 1 AND t1.trade_status_id <= 4

Could you please share you thougths on this issue?

[ili]

@sdanyliv may be, please check.

@Kempe also please try LinqToDB.Common.Configuration.Linq.UseBinaryAggregateExpression = false

[Kempe]

Cool. Thanks a lot for your help. That was really fast!