带有多个 where 子句的 EFCore 查询，它们一起充当 AND 但不充当 OR

Question

This is very obvious but tricky question. I could not find its answer on web or simply i am missing keywords that could find its answer.

Let's say we have many conditions based on which we want to filter data. These conditions are in multiple blocks. How to write them so that they work as AND clause but not OR providing they participate only in certain condition.

    var query = _entities.AsQueryable();

    if (model.CityId != default)
    {
        query = query.Where(x => x.CityId == model.CityId);
    }
    if (!string.IsNullOrWhiteSpace(model.PostalCode))
    {
        query = query.Where(x => x.Proppostcode == model.PostalCode);
    }
    if (!string.IsNullOrWhiteSpace(model.AirportCode))
    {
        query = query.Where(x => x.AirportCode == model.AirportCode);
    }

Let me know guys if this question need more details. Thank you!

Answer 1

am I missing keywords that could find its answer?

Yes, This missing keyword is Dynamic Expression or Dynamic Query . If you follow these keywords you'll find a lot of solutions to your problem.

As this tutorial said:

Dynamic Query allows you to perform dynamic where clause, select , order by , with string expression at runtime .

you can follow below links, too:

• CodeProject
• Microsoft

good luck.