Search based on a set of keywords

Question

I need to make a search based on a set of keywords, that return all the Ads related with those keywords. Then the result is a list of Categories with the Ads Count for each

Answer 1

I haven't compile-checked this or anything, so it may require some tweaking, but you're looking for something along these lines.

var matchingKac = keywordIds.Distinct().ToList()
    .Aggregate(
        keywordAdCategoryQuery.AsQueryable(),
        (q, id) => q.Where(kac => kac.Keyword_Id == id));

You're effectively saying, "Start with keywordAdCategoryQuery, and for each keyword add a .Where() condition saying that it must have that keyword in it. You could do the same thing with a for loop if you find Aggregate difficult to read.