IQueryable where clause

c#, iqueryable, linq

Solution

You don't need to write two `Where` clauses; just add another condition to your first `Where`. The second condition should use `Any` function to search for the categories you're looking for.

IArticleRepository articleRepo = unitOfWork.ArticleRepository;
List<Article> articles = new List<Article>(
                     articleRepo.GetAll()
                     .Where(a => a.Title == searchTerm &&
                                 a.Categories.Any(c => c.CategoryID == 4))
                     .OrderByDescending(a => a.CreatedDate));

For multiple categories, suppose you have your CategoryIDs in an `int[]` or `List<int>` named `MyCatIDsList`. They you can change the categories clause in the above query to this:

              a.Categories.Any(c => MyCatIDsList.Contains(c.CategoryID))

Problem

Was difficult for me to find a fitting title for this post. But I have the following: ``` IArticleRepository articleRepo = unitOfWork.ArticleRepository; List<Article> articles = new List<Article>( articleRepo.GetAll() .Where(a => a.Title == searchTerm) //.Where(a => a.Categories.Contains(Category.)) .OrderByDescending(a => a.CreatedDate)); ``` So some explanation: An `article` has , among other things, a `Title` and a `CreateDate`, and filtering through those is easy. But an `article` also has `categories` associated with it. So an `article` has an `array` property of type `Category`. Type `Category` has a property called `CategoryId` of type `int`. So in my code where it's commented out, I'm trying to `select` an `article`, which has a `category` associated with it, who's `CategoryId` is equal to.. say `4`. But I'm finding it quite difficult to express this in my C# syntax. I'm also new to C# so that's not helping either.

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