如何在实体框架中的where子句中链接替代条件

Question

I'm trying to rewrite the following query as a separate statements:

var sql = Repository.Products.AsQueryable();

sql = sql.Where(x => x.Name == "aaaaa" || x.Name == "bbbbb");

If I do it like this:

sql = sql.Where(x => x.Name == "aaaaa");
sql = sql.Where(x => x.Name == "bbbbb");

then the resulting query is equal to:

sql = sql.Where(x => x.Name == "aaaaa" && x.Name == "bbbbb");

Is there any ideas how to do it the right way?

Answer 1

The right way... is that . I mean, you could write it as

sql.Where(x => x.Name == "aaaaa").Concat(sql.Where(x => x.Name == "bbbbb"));

but that's slower , unordered and looks weirder too. I don't know what you're looking for, because the way that you posted is the right way to do it.

However , it seems you want to build the expression dynamically (judging from your comment). If so, then you're looking for a PredicateBuilder :

var predicate = PredicateBuilder.False<YourType>();
var search = new[] {"aaaaa", "bbbbb"};
foreach (string y in search)
{
    string name = y;
    predicate = predicate.Or(x => x.Name == name);
}
sql = sql.Where(predicate);

The code for PredicateBuilder is here .

Answer 2

如果你想根据条件构建谓词，请使用Predicate Builder