CODEWITHSUNDEEP
c#linqpredicatebuilder
Romias
Romias

Reputation: 14133

Apply PredicateBuilder to query a single object property of a list of items

Given the below sample models, I need to query the ITEMS by properties of its owner. This is Entity Frameworks sets, and I want to do this using LINQ.

public class Owner
  {
    public int Id { get; set; }
    public string Name { get; set; }
    //More than 20 other properties
  }

  class Item
  {
    public int Id { get; set; }
    public string Description { get; set; }
    public Owner MyOwner { get; set; }
    public int idOwner { get; set; }
    //Several others properties
  }

I already have a PredicateBuilder with the filter of Owners.

I would like to apply this predicate (it is basically the content for where clause) to the Owner object, in order to get all the Item whose Owner meets the predicate condition.

If the Owner were a list of Owners... I could use .Any(predicate) but its cardinality is 1.

EDIT:

I'm trying to do this to avoid having to get all the Owners that fulfill the predicate conditions and then do a Contains(idOwner).

db.Items.Where(c => OwnerIdsCollection.Contains(c.idOwner ?? 0));

I have seen the massive SQL CASE it creates under the hood for owners that not even have related Items.

EDIT 2 - Predicate:

public static Expression<Func<Owner, bool>> GetPredicate(OwnerCriteria criteria)
{
     var predicate = PredicateBuilder.True<Owner>();

     if (criteria.Active.HasValue) {
    predicate = predicate.And(p => p.Active == criteria.Active.Value);
     }
     //Several other criteria checkings as above

    return predicate;
}

The criteria are obtained from user filters. Then, I normally use it for querying Owners collection doing db.Owners.Where(predicate);

Now, conceptually, I need to do something like: db.Items.Where(x => /*Items filters*/ && x.MyOwner.Where(myOwnerPredicate))

Upvotes: 3

Views: 2107

Answers (1)

Ed Chapel
Ed Chapel

Reputation: 6952

Can you simply try:

Items.Where(i => predicate(i.Owner))

Based on your EDIT 2:

db.Items.AsExpandable().Where(x => /*Items filters*/ && predicate.Invoke(x.Owner))

Upvotes: 1

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