Using Entity Framework how do I filter by a foreign key using multiple enumeration values?_问答_开发者

Using Entity Framework how do I filter by a foreign key using multiple enumeration values?

开发者 https://www.devze.com 2022-12-20 22:42 出处：网络

Two tables (MainTable and EventType). EventType is represented in code as an enumeration and is foreign ke开发者_运维技巧yed in the database so that it looks like;

Public enum EventTypeId As Integer
    Blah = 1
    Blurgh = 2
    Whoo = 3
End Enum

I can run the following query fine;

From M in dbx.MainTable Where M.EventType.EventTypeId = 1

But I can't do this (psuedo code);

From M in dbx.MainTable Where M.EventType.EventTypeId.Contains(EventTypeId.Blah,EventTypeId.Whoo)

The 2nd approach is more readable and maintainable as it links to the enum, but I can't find a construct in EF that allows me to do this.

This is the current version of EF, not .Net 4.0.

In summary, what I want to do in SQL is easy, it just needs to be in EF;

Select * From MainTable Where EventTypeId In (1,3);

If you look at what you want:

In summary, what I want to do in SQL is easy, it just needs to be in EF;
Select * From MainTable Where EventTypeId In (1,3);

you should explain it as: EventTypeId should be part of (1,3). The equivalent for this is: (1,3) contains EventTypeId

What you are trying is:

But I can't do this (psuedo code)

From M in dbx.MainTable Where M.EventType.EventTypeId.Contains(EventTypeId.Blah,EventTypeId.Whoo)

But then you are trying: EventTypeId contains (1,3)

The solution is todo what you actually want in SQL in the contains syntax, but turn it around: you should look for (1,3) contains EventTypeId

So create a list of int with the specific EventType id's you are looking for. And then filter all records where EventTypeId is part of the list of id's

List<int> eventTypeIds = new List<int>();
eventTypeIds.Add((int)EventTypeId.Blah);
eventTypeIds.Add((int)EventTypeId.Whoo);

From M in dbx.MainTable Where eventTypeIds.Contains(M.EventTypeId)

Never tried something similar, but have you tested if it works by casting your enumerations to integers, as the following?