Updating List Items in SharePoint 2013 Using REST API

 Introduction

Welcome to the SharePoint 2013 REST Series. In my previous article, we saw how to delete a Custom List using the REST API.

In this article, we will discuss how to update list items in a SharePoint List using the REST API.

The SharePoint 2013 environment adds the ability for you to remotely interact with SharePoint sites using REST. So you can talk to SharePoint objects using any technology that supports standard REST capabilities. In this way, SharePoint data can be accessed anywhere and everywhere.

List of REST Access Points

The following is a list of access points that give entry into granular access points.

• Site
  
  http://server/site/_api/site
   
• Web
  
  http://server/site/_api/web
   
• User Profile
  
  http:// server/site/_api/SP.UserProfiles.PeopleManager
   
• Search
  
  http:// server/site/_api/search
   
• Publishing
  
  http:// server/site/_api/publishing

List of REST End Points

The following is a list of End points that are very commonly used in a SharePoint list.

• http://server/site/_api/web/lists
• http://server/site/_api/lists/getbytitle('listname')
• http://server/site/_api/web/lists(‘guid’)
• http://server/site/_api/web/lists/getbytitle(‘Title’)

Note: The following code is tested in my SP 2013 online environment.

Step 1: Before writing your code, please ensure that you have sufficient permission to access cross-domain requests. So I have given full permission to all the contents listed below.

Tenant	Full Permission
Site Collection	Full Permission
Web	Full Permission
List	Full Permission

 

Step 2: Navigate to the App.js file then copy the following code and paste it in.

Code

'use strict';
var hostweburl;
var appweburl;

    // This code runs when the DOM is ready and creates a context object which is
    // needed to use the SharePoint object model
    $(document).ready(function () {
            //Get the URI decoded URLs.
    hostweburl =
        decodeURIComponent(
            getQueryStringParameter("SPHostUrl"));
    appweburl =
        decodeURIComponent(
            getQueryStringParameter("SPAppWebUrl"));
               // Resources are in URLs in the form:
        // web_url/_layouts/15/resource
        var scriptbase = hostweburl + "/_layouts/15/";

        // Load the js file and continue to load the page with information about the list top level folders.
        // SP.RequestExecutor.js to make cross-domain requests

         // Load the js files and continue to the successHandler
            $.getScript(scriptbase + "SP.RequestExecutor.js", execCrossDomainRequest);
             });
             // Function to prepare and issue the request to get
          //  SharePoint data
          function execCrossDomainRequest() {
            // executor: The RequestExecutor object
            // Initialize the RequestExecutor with the app web URL.
            var executor = new SP.RequestExecutor(appweburl);
            var metatdata = "{ '__metadata': { 'type': 'SP.Data.TestListListItem' }, 'Title': 'changelistitemtitle'}";
            // Issue the call against the app web.
            // To get the title using REST we can hit the endpoint:
            //      appweburl/_api/web/lists/getbytitle('listname')/items
            // The response formats the data in the JSON format.
            // The functions successHandler and errorHandler attend the
            //      sucess and error events respectively.
            executor.executeAsync(
                {
          url:
            appweburl +
            "/_api/SP.AppContextSite(@target)/web/lists/getbytitle('TestList')/items(1)?@target='" +
            hostweburl + "'",
        method: "POST",
        body: metatdata ,
        headers: { "Accept": "application/json; odata=verbose", "content-type": "application/json; odata=verbose", "content-length": metatdata.length, "X-HTTP-Method": "MERGE", "IF-MATCH": "*" },
            success: function (data) {
                alert("success: " + JSON.stringify(data));
            },
            error: function (err) {
                alert("error: " + JSON.stringify(err));
            }
                }
            );

          }
    // This function prepares, loads, and then executes a SharePoint query to get
    // the current users information
//Utilities
// Retrieve a query string value.
// For production purposes you may want to use
// a library to handle the query string.
function getQueryStringParameter(paramToRetrieve) {
    var params =
        document.URL.split("?")[1].split("&");
    for (var i = 0; i < params.length; i = i + 1) {
        var singleParam = params[i].split("=");
        if (singleParam[0] == paramToRetrieve)
            return singleParam[1];
    }
}

Screenshot

Step 3:

While deploying, you will be prompted with the following screen. Press Trust it and proceed with the deployment.


Code Walkthrough

A .Post Method in REST API

The SharePoint 2013 REST service supports sending POST commands that include object definitions to endpoints that represent collections. In this example, Test List is a custom SharePoint list where list items are updated.

IF-MATCH header

Provides a way to verify that the object being changed has not been changed since it was last retrieved. Or, lets you specify to overwrite any changes, as shown in the following example: "IF-MATCH":"*"

B. Request Executor.JS

The cross-domain library lets you interact with more than one domain in your remote app page through a proxy. SP.RequestExecutor.js acts as a cross domain library to fetch or create a SharePoint list from your APP domain.

function execCrossDomainRequest() {
// executor: The RequestExecutor object
// Initialize the RequestExecutor with the app web URL.
var executor = new SP.RequestExecutor(appweburl); var metatdata = "{ '__metadata': { 'type': 'SP.Data.TestListListItem' }, 'Title': 'changelistitemtitle'}";

Summary

I hope this article helps you.