Want to protect your cyber security and still get fast solutions? Ask a secure question today.Go Premium

x
  • Status: Solved
  • Priority: Medium
  • Security: Private
  • Views: 42
  • Last Modified:

A linq query against two objects with same property names

I have two generic lists of objects. Each object type contains a Name, Url and Percent property.

Do I have any real need to create an abstract class (or interface) which will contain those three properties?

I need to join the two lists, sort them, and return those three properties from the Top 4 objects returned.

Can I do all this without creating an abstract class or interface containing those three properties?
0
newbieweb
Asked:
newbieweb
  • 4
  • 4
  • 3
2 Solutions
 
Fernando SotoRetiredCommented:
Hi newbieweb;

Nothing special needed. Just do a normal Join on a common property in the tow list. Something like in the pseudocode below

var q = from l1 in MyList1 
        join l2 in MyList2 on l1.joinOnProperty equals l2.joinOnProperty 
        select new 
        { 
        	Property1 = l1.Property1, 
        	Property2 = l1.Property2,
        	Property3 = l2.Property3
        }; 

Open in new window

0
 
newbiewebSr. Software EngineerAuthor Commented:
Could you re-write that query using fluent API method calls? I have a hard time getting my head about the format you used.
0
 
käµfm³d 👽Commented:
What do you mean by "join"? Are you concatenating both lists into one list, or are you actually performing a join like you would in a SQL query?
0
NEW Veeam Agent for Microsoft Windows

Backup and recover physical and cloud-based servers and workstations, as well as endpoint devices that belong to remote users. Avoid downtime and data loss quickly and easily for Windows-based physical or public cloud-based workloads!

 
Fernando SotoRetiredCommented:
Hi newbieweb;
 
The same pseudocode using method syntax.
var resultSet = Mylist1.Join(MyList2,                     // Inner Collection
                             l1 => l1.joinOnProperty,     // Outter Key Selector
                             l2 => l2.joinOnProperty,     // Inner Key Selector
                             (l1, l2) => new              // Result Selector
                             {
                                 Property1 = l1.Property1,
                                 Property2 = l1.Property2,
                                 Property3 = l2.Property3	
                             });

Open in new window

0
 
newbiewebSr. Software EngineerAuthor Commented:
Sorry, I was not looking to join. I should have looked more closely at your first post. I just need to understand if the objects contained in the list must share a common ancestor if I need to access the Name, Url and Percent.

I planned to use Add() for the lists. I guess the answer is they must share a common ancestry. True?
0
 
käµfm³d 👽Commented:
Can you rephrase your requirement? Also, example data would be helpful!
0
 
Fernando SotoRetiredCommented:
Is one or more properties that relate the tow list.
0
 
newbiewebSr. Software EngineerAuthor Commented:
not relate (like an ID), but both object types have the same properties. Name, Url and Percent. I need to do a single linq expression where I combine the two lists into one query.

Then take Top(4)

 public class ProgramCategoryItemModel
    {
        public string Name { get; set; }
             
        public string Url { get; set; }

        public int Points { get; set; }

        public bool Completed { get; set; }
    }

    public class ProgramCategoryModel
    {
        public string Name { get; set; }

        public string Url { get; set; }

        public int Points { get; set; }

       public bool Completed { get; set; }
}

I expect I will create a single interface for these and can combine the lists and query quite easily. My architect said the interface was an extra file, and suspect he knows the linq to combine the lists and query as one object type. DO you suggest creating an interface they will both enforce?
0
 
Fernando SotoRetiredCommented:
In each of the two list, List1 and List2, they both have three properties?

You state that they both have the properties Name, Url and Percent. Are those properties spelled the same way in both list?

Is what you want to create one list with all the objects from List1 and List2?
0
 
käµfm³d 👽Commented:
It sounds like you are asking this:

var list1 = new List<ProgramCategoryItemModel>(); // assume it has items
var list2 = new List<ProgramCategoryModel>(); // assume it has items

var projectedList1 = list1.Select(item => new
                                          {
                                              Name = item.Name,
                                              Url = item.Url,
                                              Points = item.Points,
                                              Completed = item.Completed,
                                          });
                                          
var projectedList2 = list2.Select(item => new
                                          {
                                              Name = item.Name,
                                              Url = item.Url,
                                              Points = item.Points,
                                              Completed = item.Completed,
                                          });
                                          
var query = projectedList1.Concat(projectedList2)
                          .OrderBy(item => item.PropertyYouWantToOrderBy)
                          .Take(4);

Open in new window


The reason for the "projectedList*" is because when you Select a new anonymous object, the compiler is creating a new, hidden type for you. You cannot instance this new type directly, but LINQ can, and when the compiler sees two anonymous object usages that have the same property definitions, it will try to reuse them. So each projection creates instances of this new type where the properties have the data that was retrieved from the items in the original list. The final query is then working with the exact same types, so it can execute the Concat without issue.
0
 
newbiewebSr. Software EngineerAuthor Commented:
Thanks!
0

Featured Post

What is SQL Server and how does it work?

The purpose of this paper is to provide you background on SQL Server. It’s your self-study guide for learning fundamentals. It includes both the history of SQL and its technical basics. Concepts and definitions will form the solid foundation of your future DBA expertise.

  • 4
  • 4
  • 3
Tackle projects and never again get stuck behind a technical roadblock.
Join Now