如何将具有过滤逻辑的链接查询重构为可重用的方法

Question

I am using EF Core to query the database and I have several queries like this in my repository class to filter the result based on the values passed as filters.

        if (!string.IsNullOrEmpty(queryObj.JobBoard))
            query = query.Where(j => j.JobBoard.JobBoardName.Contains(queryObj.JobBoard));

        if (!string.IsNullOrEmpty(queryObj.Division))
            query = query.Where(j => j.Division.Contains(queryObj.Division));

        if (!string.IsNullOrEmpty(queryObj.City))
            query = query.Where(j => j.City.Contains(queryObj.City));

        if (!string.IsNullOrEmpty(queryObj.State))
            query = query.Where(j => j.State.StateName.Contains(queryObj.State));

is there away to implement a reusable method so I don't have to repeat this for every field? (there are 12 fields to be exact).

Answer 1

Well, I don't think so because in this case, you are not just accessing the first-order object in every case. In some cases you're checking against properties on those objects.

Answer 2

Try out this. Include all the other properties with && operator.

query = query.Where(j => 
            string.IsNullOrEmpty(queryObj.JobBoard) ? true : j.JobBoard.JobBoardName.Contains(queryObj.JobBoard)
            && string.IsNullOrEmpty(queryObj.Division) ? true : j.Division.Contains(queryObj.Division)
            && string.IsNullOrEmpty(queryObj.City) ? true : j.City.Contains(queryObj.City)
            && string.IsNullOrEmpty(queryObj.State) ? true : j.State.StateName.Contains(queryObj.State)
            );