c# List adding items using For loop

Question

I have a problem with c# List, not sure where I'm missing the point while adding a new object to the Managepagesid List!

 public class Clients
    {
        [BsonId]
        public string Id { get; set; } //Object ID managed by MongoDb

        public string Name { get; set; } //Client Name

        public string Phone { get; set; } //Client Phone

        public string Email { get; set; } //Client E-mail

        public string Username { get; set; } //Client Username

        public DateTime LastModified { get; set; } //Client Last Login

        public string FB_User_Id { get; set; } //Client FB User ID

        public AccessToken UserAccessToken { get; set; } //AccessToken which is stored while user is logged in.

        public List<ManagePages> Manage_Pages_id { get; set; } //The pages maintained by the specific client
     }

I'm trying to access add a new item into ManagePage_id list but its thrwing some null exception.. Help!

Clients client = new Clients();

            client.FB_User_Id = FBData.id;
            client.Name = FBData.name;
            client.Email = FBData.email;
            client.Username = FBData.username;

            for (int index = 0; index < FBData.accounts["data"].Count; index++)
            {
                ManagePages pagedetails = new ManagePages()
                {
                    page_id = FBData.accounts["data"][index].id,
                    page_name = FBData.accounts["data"][index].name,
                    ManagePages_AccessTokens = new AccessToken()
                    {
                        AccessToken_accessToken = FBData.accounts["data"][index].access_token,
                        AccessToken_expiryDate = DateTime.Now
                    },
                    ManagePages_category = FBData.accounts["data"][index].category
                };

                var category = pagedetails.ManagePages_category;

                client.Manage_Pages_id.Add(pagedetails);
            }

Stack Trace added!

Exception>System.NullReferenceExceptionObject reference not set to an instance of an object. at Vega_MongoDB.FBDataAccess.ClientFBRepository.ClientsData(String accessToken) in g:\Development\Vega_MongoDB\Vega_MongoDB\FBDataAccess\ClientFBRepository.cs:line 48 at Vega_MongoDB.Models.ClientRepository..ctor(String connection) in g:\Development\Vega_MongoDB\Vega_MongoDB\Models\Clients\ClientRepository.cs:line 47 at Vega_MongoDB.Models.ClientRepository..ctor() in g:\Development\Vega_MongoDB\Vega_MongoDB\Models\Clients\ClientRepository.cs:line 23 at Vega_MongoDB.Controllers.ClientsController..cctor() in g:\Development\Vega_MongoDB\Vega_MongoDB\Controllers\ClientsController.cs:line 18

And I have checked the pagedetails object, it contains all the data..

Thanks

Vishnu

can you also add the stacktrace ?

Bhanu Kaushik
– Bhanu Kaushik

2012-10-19 14:36:52 +00:00
Commented Oct 19, 2012 at 14:36 — Bhanu Kaushik
– Bhanu Kaushik, Commented Oct 19, 2012 at 14:36
Where are you seeing the exception?

jrummell
– jrummell

2012-10-19 14:37:41 +00:00
Commented Oct 19, 2012 at 14:37 — jrummell
– jrummell, Commented Oct 19, 2012 at 14:37

Artem Vyshniakov · Accepted Answer · 2012-10-19 14:37:08Z

2

You should create an instance of the list before adding item:

client.Manage_Pages_id = new List<ManagePages>();
for (int index = 0; index < FBData.accounts["data"].Count; index++)
{
    ManagePages pagedetails = new ManagePages()
    {
        page_id = FBData.accounts["data"][index].id,
        page_name = FBData.accounts["data"][index].name,
        ManagePages_AccessTokens = new AccessToken()
        {
            AccessToken_accessToken = FBData.accounts["data"][index].access_token,
            AccessToken_expiryDate = DateTime.Now
        },
        ManagePages_category = FBData.accounts["data"][index].category
    };

    var category = pagedetails.ManagePages_category;

    client.Manage_Pages_id.Add(pagedetails);
}

answered Oct 19, 2012 at 14:37

Artem Vyshniakov

16.5k3 gold badges46 silver badges48 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Vishnu Vankayala Over a year ago

Awesome Bro! It works like a charm!! I'll mark as answer in 8 minutes!

Christopher Rayl Over a year ago

Good, answer, but I woulds recommend putting it the constructor in you class for DRY (Do not repeat yourself).

Christopher Rayl · Accepted Answer · 2012-10-19 14:38:45Z

1

Try adding this to your class:

public Clients()
{
  this.Manage_Pages_id = new List<ManagePages>();
}

answered Oct 19, 2012 at 14:38

Christopher Rayl

3292 silver badges10 bronze badges

1 Comment

Vishnu Vankayala Over a year ago

Yes, Made a note of it! Thanks :)

AJ. · Accepted Answer · 2012-10-19 14:39:21Z

1

You need to initialize your list before adding anything to it. You can do this in the constructor for the Clients class or in your calling code (as Artem suggested).

public class Clients
{
    //properties

    public Clients()
    {
         Manage_Pages_id = new List<ManagePages>();
    }
}

answered Oct 19, 2012 at 14:39

AJ.

16.7k22 gold badges101 silver badges156 bronze badges

1 Comment

Vishnu Vankayala Over a year ago

Yes, AJ.. Worked like a charm!

Collectives™ on Stack Overflow

c# List adding items using For loop

3 Answers 3

2 Comments

1 Comment

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

2 Comments

1 Comment

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related