在实体框架中检查相关实体的通用方法

Question

Currently I am using this code:

opportunity.Contacts.Where(x => x.IsDeleted = false).IsNullOrEmpty()

in each entity to check if any collection exists in the entity (example Opportunity ).

public bool Delete(int companyId, int opportunityId)
{
    var opportunity = _opportunityRepository.FindOne(companyId: companyId, opportunityId: opportunityId).FirstOrDefault();

    if (!opportunity.Contacts.Where(x => x.IsDeleted = false).IsNullOrEmpty())
    {
        throw new UserFriendlyException(ErrorMessages.UserFriendly.UnableToDeleteEntityHasRelatedData);
    }

    opportunity.IsDeleted = true;
    _opportunityRepository.Edit(opportunity); 
    CurrentUnitOfWork.Commit();

    return true;
}

This method is repetitive and time consuming to put in hundreds of places.

How can we make it a generic function which can check entity type and use reflection or another way to check all its properties which implement ICollection<T> and execute query to check their count?

[ForeignKey("DepartmentId")]
public virtual ICollection<DepartmentLocation> DepartmentLocations { get; set; }
[ForeignKey("DepartmentId")]
public virtual ICollection<EmployeePosition> EmployeePositions { get; set; }

Answer 1

Even if you did want to go through and resolve collections by reflection to perform a check like this, I would not recommend it. The problem domain you are looking at looks like that you want to enforce business logic around soft deletion that essentially says "I can only be marked as deleted if all of my children are first marked as deleted." The issues you would quickly face with trying to do this through reflection include:

• Hits to Lazy Loading
• Complex and slow code to inspect every object on delete.

The lazy loading risk and trying to escape it would be my first warning of dragons. I'd be looking at leveraging IQueryable from the repository rather than returning a single domain object. From there you have the flexibility to drill down into your model to determine if an object has any active children:

var activeState = _opportunityRepository.GetById(companyId, opportunityId) // return IQueryable<Opportunity>
    .Select(o=> new {o.IsDeleted, HasActiveContact = o.Contacts.Any(c=> !c.IsDeleted)})
    .SingleOrDefault();

From there you can check properties on the anon. type. The query sent to the server should remain pretty optimal in terms of performance with a single hit and the code is a simple, extendable structure that you can expand upon easily without worrying about lazy loads and such. You can expand it to return active children for instance if you want to extend a message about which children are still active to deal with before marking the parent as deleted.