在 Lambda 中使用包含 IQueryable object 和匿名字段

Question

So after reading several post about how to use Contains in Lambda I can't seem to get this to work. It should be straightforward but I am struggling big time with this up to the point where I am about to just rewrite it in Dapper.

The problem is as follow: I have a data object (build with EntityFramework ) which retrieves some data from the database, this data is being saved in a variable of type IQueryable<a> :

var data = raw.Select(p => new 
    {
        Id = p.Id,
        StatusId = p.StatusId,
        ProjectName = p.Room.Department.Project.Name,
        ProjectId = p.Room.Department.Project.Id,
        DepartmentName = p.Room.Department.Name,
        DateCreated = p.DateCreated,
        RoomName = p.Room.Name,
        UserCreatedName = p.UserCreated.Firstname + (string.IsNullOrEmpty(p.UserCreated.Insertion) ? string.Empty : " ") + p.UserCreated.Insertion + " " + p.UserCreated.Lastname,
        Comment = p.Comment,
    });

In some circumstances I need to filter the data, this filter is a list of certain project Id's:

List<Right> rights = Rights.GetItems(userId).ToList();
var projectIds = rights.Select(x => x.ItemId);

The data object should only return records which match the id's of the projectIds list .

Though for some reason I can't do this:

data = data.Where(p => x.ProjectId.Contains(projectIds);

The ProjectId field does not have a Contains overload, is this because it is a Anonymous type ?

I am working in an MVC 5 project ( .NET 4.7 ).

Answer 1

I would suspect you want to check your projectsIds list contains the project id, instead of trying to see if the projectId contains your list of project ids?

So try this?

data = data.Where(p => projectIds.Contains(p.ProjectId));

The projectId is most likely int, string or guid? the Contains method is an extension method for type generic IEnumerable. The ProjectId is most likely not an IEnumerable and therefore it does not have the overload. Contains