I’m assuming the different parts of the query are only known at runtime, i.e. you can’t just use || in a where… One lazy option is Concat – but this tends to lead to poor TSQL etc; however, I tend to be inclined to write custom Expressions instead. The approach to take depends on what … Read more
List<int> list = new List<int>() { 1, 2, 3, 4, }; IQueryable<int> query = list.AsQueryable(); If you don’t see the AsQueryable() method, add a using statement for System.Linq.
There are a few main uses. As mentioned in other answers, you can use it to mock a queryable data source using an in-memory data source so that you can more easily test methods that will eventually be used on a non-enumerable based IQueryable. You can write helper methods for manipulating collections that can apply … Read more
Don’t throw away the return value. The OrderBy extension method is does not mutate the input. Try: newView = newView.OrderBy(x => x.viewed); There is no reason why that won’t work, assuming the viewed value is correct. Also, make sure that OrderBy is after any operations (e.g. Distinct) which will ruin ordering. Happy coding!
You should check WCF Data Services which will allow you to define Linq query on the client. WCF Data Services are probably the only solution for your requirement. IQueryable is still only interface and the functionality depends on the type implementing the interface. You can’t directly expose Linq-To-Sql or Linq-To-Entities queries. There are multiple reasons … Read more
DDD Repository should encapsulate data access technicalities: Definition: A Repository is a mechanism for encapsulating storage, retrieval, and search behavior which emulates a collection of objects. It is also responsible for handling middle and end of life of domain objects. Repository interface belongs to Domain and should be based on Ubiquitous Language as much as … Read more
I get stuck on this issue today and this lib resolve it for me https://github.com/romantitov/MockQueryable completely, please refer: Mocking Entity Framework Core operations such ToListAsync, FirstOrDefaultAsync etc. //1 – create a List<T> with test items var users = new List<UserEntity>() { new UserEntity{LastName = “ExistLastName”, DateOfBirth = DateTime.Parse(“01/20/2012”)}, … }; //2 – build mock by … Read more
Assuming that your LINQ to SQL (L2S) classes are auto-generated and reflects your underlying database, the short answer is: Don’t expose IQueryable of any of your L2S classes – it would be a Leaky Abstraction. The slightly longer answer: The whole point of Repositories is to hide data access behind an abstraction so that you … Read more
AsQueryable just creates a query, the instructions needed to get a list. You can make futher changes to the query later such as adding new Where clauses that get sent all the way down to the database level. AsList returns an actual list with all the items in memory. If you add a new Where … Read more
IQueryable<T> is intended to allow a query provider (for example, an ORM like LINQ to SQL or the Entity Framework) to use the expressions contained in a query to translate the request into another format. In other words, LINQ-to-SQL looks at the properties of the entities that you’re using along with the comparisons you’re making … Read more