Using the generic type 'System.Collections.Generic.List<T>' requires '1' type arguments" error?

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Hello everybody, I am work on the asp.net Profile and currently I am trying to work on the multiple properties to showing in the form page using table's but when I run the application then it shows the this following error:

Using the generic type 'System.Collections.Generic.List<T>' requires '1' type arguments

For this application I had wrote this code:

XML

<anonymousIdentification enabled="true"/>
  <profile automaticSaveEnabled="false">

    <properties>
      <add name="Products" allowAnonymous="true" type="System.Collections.Generic.List[BusinessObject.Products]" serializeAs="Xml"/>
      <!--<add name="Id" type="int" allowAnonymous="true"/>
      <add name="Name" type="String" allowAnonymous="true" />
      <add name="ImageUrl" type="String" allowAnonymous="true"/>
      <add name="Price" type="int" allowAnonymous="true"/>
      <add name="Item" type="int" allowAnonymous="true" />-->

    </properties>
 </profile>

It seems the problem in the "Type" which I had declare inside the property but I don't get an any idea how to resolve it.Here's in this code the "BusinessObject is the namespace and the "Products" is the class name.So please help me to resolve this problem and tell me its appropriate solution.Help me please.

Posted 9-Oct-14 1:38am

AnoopGharu

Updated 9-Oct-14 1:42am

v2

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BillWoodruff 9-Oct-14 8:31am

I'm not deep enough into XML to speak with any authority here, but try:

System.Collections.Generic.List<businessobject.products>

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Richard Deeming · Answer 1 · 2014-10-09T02:34:00

Solution 1

You might be able to get away with specifying the correct generic type name:

System.Collections.Generic.List`1[BusinessObject.Products]

However, the simplest solution would be to use a custom non-generic collection class:

C#

using System;
using System.Collections.Generic;

namespace BusinessObject
{
    public class ProductsCollection : List<Products>
    {
        public ProductsCollection(IEnumerable<Products> collection) : base(collection)
        {
        }
        
        public ProductsCollection(int capacity) : base(capacity)
        {
        }
        
        public ProductsCollection()
        {
        }
    }
}

Posted 9-Oct-14 2:34am

Richard Deeming

Comments

BillWoodruff 9-Oct-14 9:04am

Do you think the problem here may be the use of square brackets [] rather than <> ?

Richard Deeming 9-Oct-14 9:21am

Everything I've seen says to use square brackets. I think the OP was just missing the "`1" between the type name and type parameters.

BillWoodruff 9-Oct-14 17:18pm

Thanks; obviously I should have kept my mouth shut :)

AnoopGharu 10-Oct-14 3:59am

Thank you So much Sir for your best concerned, anyway can you tell me please why you had to use "`1" in the Generic List and I have these above properties which I had already declared in the comments inside the profile.Can you tell me please how I need to define my these properties in the new PorductsCollection class with the use of Enumeration or without the use of it.Please help me because I am new to asp.net.

Richard Deeming 10-Oct-14 4:09am

The "`1" is added to the name of a generic type to indicate the number of type parameters. This "name mangling" allows compilers to support multiple generic types with the same name but a different number of parameters. For more information, look at the remarks of the Type.GetType method[^] on MSDN.

If you go with a custom non-generic collection class, you don't need to specify the generic type parameters. You would just declare your property's type as "BusinessObject.ProductsCollection". Since the collection class is derived from List<BusinessObject.Products>, you shouldn't need to change any code that reads it. Only code that assigns a new value to the property would need to change.

AnoopGharu 10-Oct-14 10:21am

Hello sir,I had create the following ProductsCollection class:

namespace BusinessObject
{
public class ProductsCollection:List<Products>
{
public ProductsCollection()
{
List<Products> productcollection = new List<Products>();
Products product = new Products();
product.ImageUrl = Convert.ToString("ImageUrl");
product.Name = Convert.ToString("Name");
//product.Price = Convert.ToInt32("Price");
//product.Item = Convert.ToInt32("Item");

productcollection.Add(product);

}
}
}

and on the Add_To_Cart button I did the following coding:

protected void Button1_Click(object sender, EventArgs e)
{
BusinessObject.ProductsCollection bp = new BusinessObject.ProductsCollection();
Profile.Products.Add(bp);
Profile.Save();
}

but when I run the project it shows this error "Attempting to load this property's type resulted in the following error: Could not load type 'System.Collections.Generic.List`1[BusinessObject.ProductsCollection]'.".So please help to resolve this error and even though I had did lot of googling but still didn't find the exact solution and also tell me that I declare the right properties at there or nor.So finally I update here.If you can then please give me its appropriate solution.