复杂的LINQ或EF查询

Question

I have the following 3 classes.

A workflow configuration has one brand and one workflowtype.

I need one method in linq or EF that gets me all the brands of existing workflowconfiguration and another method that gets me all the brands of non existing workflow configuration.

I am lost cause I dont know where to start.

public class Brand
    {
        public int BrandId { get; set; }
        public string Name { get; set; }
    }


  public class WorkflowType
    {
        public int WorkflowTypeId { get; set; }
        public string Name { get; set; }
    }

 public class WorkflowConfiguration
    {
        public int WorkflowConfigurationId { get; set; }
        public WorkflowType WorkflowType { get; set; }
        public Brand Brand { get; set; }
        public virtual ICollection<Approver> Approvers { get; set; }

    }

Update1 Here are how my tables would look like and the expected result

Brand

1. Audi

2. Volkswagen

3. Mercedes

WorkflowTYpes

1. type 1

2. type 2

3. type 3

WorkflowConfiguration

brandid, workflowtype id

1 ------------ 1

1 -------------2

List<string> GetBrandsForExistingWorkflowType(string worfklowtype)

If I pass type1 to this method it should return: Audi because for type1, audi exists on the table

List<string> GetBrandsForNonExistingWorkflowType(string workflowType)

If I pass type1 to this method it should return. Volkswagen and Mercedes because for type1, those 2 brands are not in the relationship.

Answer 1

I think this is what you want:

List<string> GetBrandsForExistingWorkflowType(string worfklowtype)
{
    var result = db.WorkflowConfigurations
                 .Where(x => x.WorkflowType.Name == worfklowtype)
                 .Select(x => x.Brand);
    return result;
}

List<string> GetBrandsForNonExistingWorkflowType(string workflowType)
{
    var excluded = GetBrandsForExistingWorkflowType(string worfklowtype);
    var result = db.Brands.Except(excluded);
    return result;
}