c# - Add range is not working with list -

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• what nullreferenceexception, , how fix it? 29 answers

i having payee contact details object

public class payeecontactdetails {      //[jsonproperty("id")]     //[defaultvalue("")]     //public int id { get; set; }      [jsonproperty("contact_name")]     [defaultvalue("")]     public string contactname { get; set; }      [jsonproperty("contact_email")]     [defaultvalue("")]     public string contactemail { get; set; }     ........     ........ } 

and here having payeecontactgroup class

 public class payeecontactgroup  {        [jsonproperty("payee_contacts")]         public list<payeecontactdetails> payeecontact { get; set; }   } 

here getting data api response on page page after completion of pages need send data @ time db

for purpose doing this

 payeecontactgroup payeecontactdetails = new payeecontactgroup();    var response = httpclient.getasync(uri).result;   if (response.issuccessstatuscode)   {      string data = response.content.readasstringasync().result;      var payeecontactgroupdetails = jsonconvert.deserializeobject<payeecontactgroup>(data);       if(payeecontactgroupdetails.payeecontact != null && payeecontactgroupdetails.currentpage == 1)       {          payeecontactdetails.payeecontact = payeecontactgroupdetails.payeecontact.tolist();       }       else if(payeecontactgroupdetails.payeecontact != null && payeecontactgroupdetails.currentpage > 1)       {           payeecontactdetails.payeecontact.addrange(payeecontactgroupdetails.payeecontact); // error @ line        }       .......       ......   }          

but getting error @ line

"payeecontactdetails.payeecontact.addrange(payeecontactgroupdetails.payeecontact);" error : "object reference not set object"

could 1 please on .... many in advance

you need create list first:

public class payeecontactgroup  {        [jsonproperty("payee_contacts")]         public list<payeecontactdetails> payeecontact { get; set; } = new list<payeecontactdetails>();   } 

or create list when necessary:

payeecontactgroup payeecontactdetails = new payeecontactgroup();  var response = httpclient.getasync(uri).result; if (response.issuccessstatuscode) {    string data = response.content.readasstringasync().result;    var payeecontactgroupdetails = jsonconvert.deserializeobject<payeecontactgroup>(data);     if(payeecontactgroupdetails.payeecontact != null && payeecontactgroupdetails.currentpage == 1)     {        payeecontactdetails.payeecontact = payeecontactgroupdetails.payeecontact.tolist();     }     else if(payeecontactgroupdetails.payeecontact != null && payeecontactgroupdetails.currentpage > 1)     {           if(payeecontactdetails.payeecontact == null)          {               payeecontactdetails.payeecontact = new list<payeecontactdetails>();          }          payeecontactdetails.payeecontact.addrange(payeecontactgroupdetails.payeecontact); // error @ line      }       .......       ...... }