Forms Service API

using Newtonsoft.Json;
using Newtonsoft.Json.Linq;
using System;
using System.Collections.Generic;
using System.Net;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Text;

namespace EPiServer.Forms.ServiceApi.WebTest {
  public class OAuth2Client {
    private string _baseUrl, _username, _password, _accessTokenUri;

    public OAuth2Client(string baseUrl, string username, string password, string accessTokenUri) {
      _baseUrl = baseUrl;
      _username = username;
      _password = password;
      _accessTokenUri = accessTokenUri;
    }

    public string GetData(string uri, string accessToken) {
      using(var client = new HttpClient()) {
        client.BaseAddress = new Uri(_baseUrl);
        client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", accessToken);

        var response = client.GetAsync(uri).Result;
        if (response.StatusCode == HttpStatusCode.OK) {
          var content = response.Content.ReadAsStringAsync().Result;
          return content;
        }
      }

      return string.Empty;
    }

    public string DeleteData(string uri, string accessToken, int formsId, IEnumerable < string > recordIds) {
      using(var client = new HttpClient()) {
        client.BaseAddress = new Uri(_baseUrl);
        client.DefaultRequestHeaders.Accept.Clear();
        client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
        client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", accessToken);

        var content = JsonConvert.SerializeObject(new {
          Id = formsId,
            SubmissionIds = recordIds
        });

        var postContent = new StringContent(content, Encoding.UTF8, "application/json");
        var response = client.PostAsync(uri, postContent).Result;
        return response.StatusCode.ToString();
      }
    }

    public string GetAccessToken() {
      var token = string.Empty;
      using(var client = new HttpClient()) {
        client.BaseAddress = new Uri(_baseUrl);
        var fields = new Dictionary < string,
          string > {
            {
              "grant_type",
              "client_credentials"
            },
            {
              "client_id",
              _username
            },
            {
              "client_secret",
              _password
            },
            {
              "scope",
              "epi_service_api"
            }
          };
        var response = client.PostAsync(_accessTokenUri, new FormUrlEncodedContent(fields)).Result;
        if (response.StatusCode == HttpStatusCode.OK) {
          var content = response.Content.ReadAsStringAsync().Result;
          token = (string) JObject.Parse(content).GetValue("access_token");
        }
      }
      return token;
    }
  }
}

private const string AccessTokenURI = "/api/episerver/connect/token";
private const string FormDataURI = "/EPiServer.Forms.ServiceApi/GetFormData(Id={0},Language=null)?$top=10";
private const string FormMappingURI = "/EPiServer.Forms.ServiceApi/GetFieldMapping(Id={0},Language=null)";
private const string FormsInfoURI = "/EPiServer.Forms.ServiceApi/GetFormsInfo(Language=null)";
private const string FormsDeleteURI = "/EPiServer.Forms.ServiceApi/DeleteFormData";
private static readonly string Username = ConfigurationManager.AppSettings["username"]; // clientId added to access ServiceApi on step 3
private static readonly string Password = ConfigurationManager.AppSettings["password"]; // clientSecret added to access ServiceApi on step 3
private static readonly string SiteUrl = ConfigurationManager.AppSettings["siteUrl"]; // ex: https://vnwks30:17005/

………………………………………………………………………………………………………………………………….
protected void FetchData_Click(object sender, EventArgs e) {
  if (string.IsNullOrEmpty(FormId.Text)) {
    return;
  }

  // for request to https site
  System.Net.ServicePointManager.ServerCertificateValidationCallback = delegate {
    return true;
  };
  var oAuthClient = new OAuth2Client(SiteUrl, Username, Password, AccessTokenURI);
  var accessToken = oAuthClient.GetAccessToken();
  var formsInfo = oAuthClient.GetData(FormsInfoURI, accessToken);
  var mappings = oAuthClient.GetData(string.Format(FormMappingURI, FormId.Text), accessToken);
  var data = oAuthClient.GetData(string.Format(FormDataURI, FormId.Text), accessToken);

  // get the first record return from above function and delete it
  if (data != null) {
    var dataObj = JObject.Parse(data);
    var firstId = dataObj["value"].First["Id"];
    var recordIds = new List < string > {
      firstId.ToString()
    };
    var deleteFirstRecord = oAuthClient.DeleteData(FormsDeleteURI, accessToken, int.Parse(FormId.Text), recordIds);
  }

  // delete all records
  //var dataObj = JObject.Parse(data);
  //var recordIds = new List<string>();
  //foreach (var obj in dataObj["value"])
  //{
  //    recordIds.Add(obj["Id"].ToString());
  //}
  //var deleteAllRecord = oAuthClient.DeleteData(FormsDeleteURI, accessToken, int.Parse(FormId.Text), recordIds);
}