Not able to get ID of user using their user name - error in _api/web/siteusers

Question

I am trying to find the ID of the user using _api/web/siteusers in Office 365

I get the below error

User cannot be found

But, when I add user to some people picker field in list item, it starts working

I am using the below code

function GetUserId(userName) {
    //userName format = i:0#.f|membership|[email protected]
    var siteUrl = _spPageContextInfo.siteAbsoluteUrl;
    var requesturl = "/_api/web/siteusers(@v)?@v='" + encodeURIComponent(userName) + "'";
    if (userName.indexOf("|") < 0) {
        requesturl = "/_api/web/sitegroups/getbyname('" + encodeURIComponent(userName) + "')?$select=id";
    }
    var call = $.ajax({
        url: siteUrl + requesturl,
        method: "GET",
        headers: { "Accept": "application/json; odata=verbose" }
    });
    return call;
};

Answer 1

Try using CSOM:

function getUserId(loginName) {
        var context = new SP.ClientContext.get_current();
        this.user = context.get_web().ensureUser(loginName);
        context.load(this.user);
        context.executeQueryAsync(
        Function.createDelegate(null, ensureUserSuccess),
        Function.createDelegate(null, onFail)
    );
 }
 function ensureUserSuccess() {
        console.log(this.user.get_id());
 }
 function onFail(sender, args) {
        alert('Query failed. Error: ' + args.get_message());
 }

Answer 2

The code which at me normally works (NTLM authentication):

function GetUserId(userName) {
        var prefix = "i:0#.w|";
        var siteUrl = _spPageContextInfo.siteAbsoluteUrl;
        var accountName = prefix + userName;
        $.ajax({
            url: siteUrl + "/_api/web/siteusers(@v)?@v='" + 
                encodeURIComponent(accountName) + "'",
            method: "GET",
            headers: { "Accept": "application/json; odata=verbose" },
            success: function (data) {
                alert("Received UserId" + data.d.Id);
                alert(JSON.stringify(data));
            },
            error: function (data) {
                console.log(JSON.stringify(data));
            }
        });
    }

Answer 3

Since you are setting your call to a var, try using the .done() function with it. Example below:

var call = $.ajax({
    url: siteUrl + requesturl,
    method: "GET",
    headers: { "Accept": "application/json; odata=verbose" }
});
call.done(function(data) {
    console.dir(data);
    //do stuff
});

Thsi should work for how you are using your REST calls. Good Luck!