SharePoint rest api synchronous call using deferred promise and then Example

This SharePoint Rest API tutorial, we will discuss, how to use deferred promise and then in Rest API in SharePoint Online or SharePoint 2013/2016 to make a synchronous call.

We can use Deferred promise and then in Rest API in SharePoint 2013/2016/Online to make calls. Let us consider an example and then we will see how we can implement this.

Here let us take a list which has three columns:

• Title
• FirstName
• LastName

And let us create an HTML form where the user can enter a title, first name, and last name and click on submit button to save the data in the list and once the data get saved it should display in a div. So in this situation, we need a synchronous call.

Our Save to list code should execute first and once it is complete then our Retrieve list items code should execute which will fetch the data from list and show in a div.

SharePoint rest api synchronous call

We can use Deferred promise and then to make SharePoint rest api synchronous call.

Syntax:

Here we can declare Deferred like below

var deferred = $.Deferred();

And then once method() execute completely method2() will get called.

method1().then(function(data) {
method2();
});
});

In the first method (method1()), we have to return promise() like below:

var method1 = function () {
return deferred.promise();
}

Then we can write the success and failure method like below:

function onQuerySucceeded(sender, args) {
deferred.resolve(args);
}

function onQueryFailed() {
deferred.reject(sender, args);
}

Full Code:

<div id="AddListData">
<div>
Title:
<br />
<input type="text" id="txtTitle" />
</div>
<div>
Industry:
<br />
<input type="text" id="txtIndustry" />
</div>
<br />
<div>
<input id="btnSubmit" type="button" value="Submit" />
</div>
</div>
<div id="divResult"></div>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.2/jquery.min.js"></script>
<script>
var deferred = $.Deferred();
$(function () {
bindButtonClick();
});

function bindButtonClick() {
$("#btnSubmit").on("click", function () {
addListItem().then(function (data) {
getListData();
});
});
}

var addListItem = function () {
var title = $("#txtTitle").val();
var industry = $("#txtIndustry").val();
var siteUrl = _spPageContextInfo.webAbsoluteUrl;
var fullUrl = siteUrl + "/_api/web/lists/GetByTitle('MyCompanyInfo')/items";
$.ajax({
url: fullUrl,
type: "POST",
data: JSON.stringify({
'__metadata': { 'type': 'SP.Data.MyCompanyInfoListItem' },
'Title': title,
'Industry': industry
}),

headers: {
"accept": "application/json;odata=verbose",
"content-type": "application/json;odata=verbose",
"X-RequestDigest": $("#__REQUESTDIGEST").val()
},
success: onQuerySucceeded,
error: onQueryFailed
});
return deferred.promise();
}

function onQuerySucceeded(sender, args) {
deferred.resolve(args);
}

function onQueryFailed() {
deferred.reject(sender, args);
}

function getListData() {
var fullUrl = _spPageContextInfo.webAbsoluteUrl + "/_api/web/lists/getByTitle('MyCompanyInfo')/items";
$.ajax({
url: fullUrl,
type: "GET",
headers: {
"accept": "application/json;odata=verbose",
"content-type": "application/json;odata=verbose",
},
success: onQuerySucceeded1,
error: onQueryFailed1
});
}
function onQuerySucceeded1(data) {
var listItemInfo = ";
$.each(data.d.results, function (key, value) {
listItemInfo += '<b>Title:</b> ' + value.Title + ' – <b>Industry:</b> ' + value.Industry + '<br />';
});
$("#divResult").html(listItemInfo);
}
function onQueryFailed1() {
alert('Error!');
}
</script>

Once you save the code, the form will appear like below. User can enter a value and click on submit, it will first save the data to the SharePoint list and then display the result in the page.

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This is how we can make rest api synchronous call in SharePoint Online or SharePoint 2013/2016.