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I got an InvalidOperationException with message "Could not format node 'New' for execution as SQL." at the following query.

var source = db.Users.Where(a => (bool)db.Filter(a, keyword)).ToList();

here "Filter" is a database function that have two parameters and returns boolean.

I'm using linq to postgresql ,
and I expect that generated sql query like "select u.* from userrs u where filter(u, 'hebele')"

Please specify the DBMS you are using.

I will send you a test project in a letter, please check that it is not blocked by your mail filter. The projects includes a model created for the PostgreSQL database.

Please describe what should be changed in the sample to reproduce the problem.

Thanks for your interest.

I'm using postgresql 9.0.

My function accepts takes record as parameter, not a field value. So, my linq query likes "db.Filter(a, keyword)" not "db.Filter(a.Name, keyword)". this is the main difference.

I don't know, this usage my be silly.
Probably database servers except postgresql does not support this usage.

In this case, the problem is that an object of a custom type (i.e., the row type of the 'users' table) actually should be passed as a function argument. Since LinqConnect does not support user-defined types, such an operation is not allowed.

A possible way to resolve the issue is to create (and use in the model) an overload of the 'filter' function that takes parameters of simple types only.