AddCustomField is not working in HelloSignAPI

Question

The value is not filled in textboxes.. Textbox name is assigned like FullName and Company in Hellosign Templates. Then add code like below, Even the value is not filled in textboxes..
Please help this issue.. Thanks for in advance..

var request = new TemplateSignatureRequest();
request.AddTemplate(templateID);
request.Title = "Test Development";
request.Subject = "REG : Test Generate Document";
request.Message = "Please review these three contracts and sign them at your earliest convenience.";
request.AddSigner("Client", signer.Email, signer.Name);
request.AddCustomField("FullName", "Test Development 2021");
request.AddCustomField("Company", "123 Main St, Anytown, ST 12345");
request.TestMode = true;
var response = client.SendSignatureRequest(request);

Answer 1

The first 2 things you'll want to check are:

1. Are the fields you want to pre-fill assigned to 'Sender' on the template you're using?
2. Do the Merge field labels of these fields match the field names you're passing in with request.AddCustomField() exactly? Any discrepancy will result in the custom field values not mapping to the fields on the template.

Using your custom field names, the fields on the template should look like this when you open the template in the editor on the UI: merge fields in editor

If you've gone through the two recommendations above, and the values still aren't populating, try adding custom fields using the Client.AdditionalParameters Dictionary object. This allows you to inject parameters into your request:

client.AdditionalParameters.Add("custom_fields", "[{\"name\":\"FullName\",\"value\":\"Test Development 2021\"},{\"name\":\"Company\",\"value\":\"123 Main St, Anytown, ST 12345\"}]");