How to find the parent list using Linq Query for below

Rakesh reddy

8y1.1kLearn iOS Programming

I Have classes

public class User

{

Int UserId;

String UserName

products List

}

public class Product

{

int ProductId;

int ProductName;

}

var data = new List();

data.Add(1, new List { new Product {prdouctId= 1, ProductName = "Name1"} , new Product {ProductId=2, ProductName="Name2"}}

data.Add(2, new List { new Product {prdouctId= 2, ProductName = "Name2"} , new Product {ProductId=3, ProductName="Name3"}}

data.Add(3, new List { new Product {prdouctId= 4, ProductName = "Name4"} , new Product {ProductId=2, ProductName="Name1"}}

How we get the users List with Linq query who are mapped product wise

Expected Result:

----------------------

ProdcutId UsersId

1 {1,3}

2 {1,2,3}

3 {2,3}

3 Replies

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Hemant Jindal8y ago
Hi Rakesh

I have changed the implementation a bit. Please have a look and hope this works for you
static List InitializeUserProduct()
{
    List Users = new List();
    List Products = new List();

    Products.Add(new Product() { ProductId = 1, ProductName = "Product 1" });
    Products.Add(new Product() { ProductId = 2, ProductName = "Product 2" });
    Products.Add(new Product() { ProductId = 3, ProductName = "Product 3" });
    Products.Add(new Product() { ProductId = 4, ProductName = "Product 4" });

    User user = new User() {UserId = 1, UserName = "User 1"};
    user.Products.Add(Products.FirstOrDefault(p => p.ProductId == 1));
    user.Products.Add(Products.FirstOrDefault(p => p.ProductId == 2));
    Users.Add(user);
    user = new User() { UserId = 2, UserName = "User 2" };
    user.Products.Add(Products.FirstOrDefault(p => p.ProductId == 2));
    user.Products.Add(Products.FirstOrDefault(p => p.ProductId == 3));
    Users.Add(user);
    user = new User() { UserId = 3, UserName = "User 3" };
    user.Products.Add(Products.FirstOrDefault(p => p.ProductId == 1));
    user.Products.Add(Products.FirstOrDefault(p => p.ProductId == 2));
    user.Products.Add(Products.FirstOrDefault(p => p.ProductId == 3));
    user.Products.Add(Products.FirstOrDefault(p => p.ProductId == 4));
    Users.Add(user);
    Products.ForEach(product =>
    {
        var users = Users.Where(u => u.Products.Exists(p => p.ProductId == product.ProductId)).Select(u => new User() { UserId = u.UserId, UserName = u.UserName });
        string associatedUsers = string.Join(", ", from item in users.AsEnumerable() select item.UserName);
        Console.WriteLine("Product Id: {0}, Product Name : {1}  Users: {2} ", product.ProductId, product.ProductName, associatedUsers);
    });

    return Users;
}
Please let me know if you have any queries

Thanks
Hemant Jindal
Rakesh reddy8y ago
Hi Hemant,

Thank you for response,

But while finding users based on Product wise you are hardcoded product==1, But in my scenariao i should not data is dynamic

and with single Linq query i have to get the belwo result

Expected Result:
----------------------
ProdcutId UsersId
1              {1,3}
2              {1,2,3}
3              {2,3}

finally i need to get the only 3 records with List property for each row
Hemant Jindal8y ago
i Rakesh

I hope sample code help you
public class User
{
    public int UserId { get; set; }
    public string UserName { get; set; }

    private List _products;
    public List Products
    {
        get { return _products ?? (_products = new List()); }
        set { _products = value; }
    }
}
public class Product
{
    public int ProductId { get; set; }

    public string ProductName { get; set; }
}
    static List InitializeUserProduct()
    {
        List Users = new List();
        User user = new User() {UserId = 1, UserName = "User 1"};
        user.Products.Add(new Product() {ProductId = 1, ProductName = "Product 1"});
        user.Products.Add(new Product() {ProductId = 2, ProductName = "Product 2"});
        Users.Add(user);
        user = new User() { UserId = 2, UserName = "User 2" };
        user.Products.Add(new Product() { ProductId = 2, ProductName = "Product 2" });
        user.Products.Add(new Product() { ProductId = 3, ProductName = "Product 3" });
        Users.Add(user);
        user = new User() { UserId = 3, UserName = "User 3" };
        user.Products.Add(new Product() { ProductId = 1, ProductName = "Product 1" });
        user.Products.Add(new Product() { ProductId = 3, ProductName = "Product 3" });
        user.Products.Add(new Product() { ProductId = 4, ProductName = "Product 4" });
        Users.Add(user);
        var users = Users.Where(u => u.Products.Exists(p => p.ProductId == 1)).Select(u => new User(){ UserId = u.UserId, UserName = u.UserName});

        return Users;
    }
ic void Main(string[] args)
    {
        InitializeUserProduct();
        Console.ReadLine();
    }
thanks
Hemant Jindal