System.Linq.Dynamic - Can I use IN clause in WHERE statement

问题

I have dynamic linq WHERE statement:

dataContext.Table.Where("id = 0 Or id = 1 Or id = 2 Or ...");

I want change to:

dataContext.Table.Where("id IN (0, 1, 2, ...)");

But it doesn´t work. How can I do this for better performance?

回答1:

From How to use “contains” or “like” in a dynamic linq query?

//edit: this is probably broken, see below
ids = new int[] {1,2,3,4};
dataContext.Table.Where("id.Contains(@0)", ids);

Aside: It is good practice to use placeholders in dynamic linq expressions. Otherwise you may open yourself to linq injection attacks (Is Injection Possible through Dynamic LINQ?)

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EDIT:

actually I think I messed this up. Unfortunately I cannot test this at the moment. But I think the correct syntax in this case should be dataContext.Table.Where("@0.Contains(id)",ids);, not the other way around, and that version does not work out-of-the-box.

See here for a way to add this functionality to dynamic link. You need to modify the library for this.

回答2:

var ids = new int[] {1,2,3,4};
dataContext.Table.Where(f => ids.Contains(f.id))

回答3:

it seems that in version 1.0.4 of System.Linq.Dynamic , we can use the following syntax dataContext.Table.Where("@0.Contains(outerIt.id)",ids); as it was made and presented in the already cited blog: here

来源：https://stackoverflow.com/questions/10186683/system-linq-dynamic-can-i-use-in-clause-in-where-statement