changing list item using Rest API not working

Question

following is my code. I am trying to update a Choice ListITem (dropdownlist) in a Custom list using Rest API. I have debugged the code it goes into success handler but the Item still has the old value.

I am trying to change Status to closed. I have noticed even if I change the Status to Status1 some Field that does not exists in the list it goes to Succeess handler anyway.

var data = GetListItem(); //using Rest Api.
var newStatus = "Closed";
var name = "MyList";
var itemType = "SP.Data.MyListListItem";

        var item = {
            "__metadata": { "type": itemType },
            "Status": newStatus
        };
        var t = JSON.stringify(item);

        $.ajax({
            url: data.__metadata.uri, //I have checked uri is "https://condev.sharepoint.com/_api/Web/Lists(guid'98b0412e-e32f-41f2-b1a4-1324ad65fce9')/Items(2)"
            method: "POST",
            body: JSON.stringify(item), // it is "{\"__metadata\":{\"type\":\"SP.Data.MyListListItem\"},\"Status\":\"Closed\"}"
            headers: { 
                "Accept": "application/json;odata=verbose",
                "X-RequestDigest": $("#__REQUESTDIGEST").val(),
                "X-HTTP-Method": "MERGE",
                "If-Match": data.__metadata.etag
            },
            success: function (data) {
                alert("Project status changed to closed");
            },
            error: function (data, errorCode, errorMessage) {
                alert("Rest Api error (upadate listitem)=" + errorMessage);
            }
        });

Answer 1

The following example demonstrates how to perform Update operation for a List Item via SharePoint REST API:

// Update Operation
// listName: The name of the list you want to get items from
// siteurl: The url of the site that the list is in. // title: The value of the title field for the new item
// itemId: the id of the item to update
// success: The function to execute if the call is sucesfull
// failure: The function to execute if the call fails
function updateListItem(itemId, listName, siteUrl, itemProperties, success, failure) {
    var itemType = GetItemTypeForListName(listName);
    itemProperties["__metadata"] = { "type": itemType };

    getListItemWithId(itemId, listName, siteUrl, function (data) {
        $.ajax({
            url: data.__metadata.uri,
            type: "POST",
            contentType: "application/json;odata=verbose",
            data: JSON.stringify(itemProperties),
            headers: {
                "Accept": "application/json;odata=verbose",
                "X-RequestDigest": $("#__REQUESTDIGEST").val(),
                "X-HTTP-Method": "MERGE",
                "If-Match": data.__metadata.etag
            },
            success: function (data) {
                success();
            },
            error: function (data) {
                failure(data);
            }
        });
    }, function(data){
        failure(data);
    });
}

// READ operation
// itemId: The id of the item to get
// listName: The name of the list you want to get items from
// siteurl: The url of the site that the list is in. 
// success: The function to execute if the call is sucesfull
// failure: The function to execute if the call fails
function getListItemWithId(itemId, listName, siteurl, success, failure) {
    var url = siteurl + "/_api/web/lists/getbytitle('" + listName + "')/items?$filter=Id eq " + itemId;
    $.ajax({
        url: url,
        method: "GET",
        headers: { "Accept": "application/json; odata=verbose" },
        success: function (data) {
            if (data.d.results.length == 1) {
                success(data.d.results[0]);
            }
            else {
                failure("Multiple results obtained for the specified Id value");
            }
        },
        error: function (data) {
            failure(data);
        }
    });
}

function GetItemTypeForListName(name) {
    return "SP.Data." + name.charAt(0).toUpperCase() + name.slice(1) + "ListItem";
}

Example

Then, the update operation for list item value of Choice field type would be:

var itemProperties = {
        "Status": 'ChoiceValue'
    }; 
updateListItem(4,'Documents',_spPageContextInfo.webAbsoluteUrl,itemProperties,
   function(){    
   },
   function(error){
    console.log(JSON.stringify(error));
   }
);

References

Manipulating list items in SharePoint Hosted Apps using the REST API