CRM 2016 - WEB API CRUD Operations (Part 1)

How to CRUD with the new CRM 2016 Web API in Javascript

In this post I wanted to talk of the new Web API available in CRM 2016. I am not sure about you but I could not find any example, other than the basic Create operation provided by Microsoft, of how to use the new Web API for CRUD operations.
So here it is an example of a RETRIEVE (and the CREATE from the Microsoft example found here) query using the Web API, I will be adding more examples of "Retrieve Multiple, "Update" and "Delete" as I discover how to implement them.

"use strict";
var bd_Utilities = window.bd_Utilities || {};
bd_Utilities.WebAPI = bd_Utilities.WebAPI || {};

(function () {
    this.create = function (entitySetName, entity, successCallback, errorCallback) {
        var req = new XMLHttpRequest();
        req.open("POST", encodeURI(getWebAPIPath() + entitySetName), true);
        req.setRequestHeader("Accept", "application/json");
        req.setRequestHeader("Content-Type", "application/json; charset=utf-8");
        req.setRequestHeader("OData-MaxVersion", "4.0");
        req.setRequestHeader("OData-Version", "4.0");
        req.onreadystatechange = function () {
            if (this.readyState == 4 /* complete */) {
                req.onreadystatechange = null;
                if (this.status == 204) {
                    if (successCallback)
                        successCallback(this.getResponseHeader("OData-EntityId"));
                }
                else {
                    if (errorCallback)
                        errorCallback(bd_Utilities.WebAPI.errorHandler(this.response));
                }
            }
        };
        req.send(JSON.stringify(entity));
    };

this.retrieve = function (id, entitySetName, select, expand, successCallback, errorCallback) {
        var req = new XMLHttpRequest();
        req.open("GET", encodeURI(getWebAPIPath() + entitySetName + "(" + id + ")" + select), true);
        req.setRequestHeader("Accept", "application/json");
        req.setRequestHeader("Content-Type", "application/json; charset=utf-8");
        req.setRequestHeader("OData-MaxVersion", "4.0");
        req.setRequestHeader("OData-Version", "4.0");
        req.onreadystatechange = function () {
            if (this.readyState == 4 /* complete */) {
                req.onreadystatechange = null;
                if (this.status == 200) {
                    if (successCallback)
                        successCallback(JSON.parse(this.responseText, bd_Utilities.WebAPI.dateReviver));
                }
                else {
                    if (errorCallback)
                        errorCallback(bd_Utilities.WebAPI.errorHandler(this.response));
                }
            }
        };
        req.send();
    };
 
//This is the calling function:

search: function () {
        bd_Utilities.WebAPI.retrieve("00000000-0000-0000-0000-000000000090", "contacts", "?$select=firstname,lastname", "",
       
        function (result) {
            var contact = result;
            console.log("Contact retrieved")
        },
        function (error) { console.log(error.message); });
    }

//And these are some helper functions from the CRM SDK

    //Internal supporting functions
    function getClientUrl() {
        //Get the organization URL
        if (typeof GetGlobalContext == "function" &&
            typeof GetGlobalContext().getClientUrl == "function") {
            return GetGlobalContext().getClientUrl();
        }
        else {
            //If GetGlobalContext is not defined check for Xrm.Page.context;
            if (typeof Xrm != "undefined" &&
                typeof Xrm.Page != "undefined" &&
                typeof Xrm.Page.context != "undefined" &&
                typeof Xrm.Page.context.getClientUrl == "function") {
                try {
                    return Xrm.Page.context.getClientUrl();
                } catch (e) {
                    throw new Error("Xrm.Page.context.getClientUrl is not available.");
                }
            }
            else { throw new Error("Context is not available."); }
        }
    }

    function getWebAPIPath() {
        return getClientUrl() + "/api/data/v8.0/";
    }

    //Internal validation functions
    function isString(obj) {
        if (typeof obj === "string") {
            return true;
        }
        return false;

    }

    function isNull(obj) {
        if (obj === null)
        { return true; }
        return false;
    }
    function isUndefined(obj) {
        if (typeof obj === "undefined") {
            return true;
        }
        return false;
    }
    function isFunction(obj) {
        if (typeof obj === "function") {
            return true;
        }
        return false;
    }
    function isNullOrUndefined(obj) {
        if (isNull(obj) || isUndefined(obj)) {
            return true;
        }
        return false;
    }
    function isFunctionOrNull(obj) {
        if (isNull(obj))
        { return true; }
        if (isFunction(obj))
        { return true; }
        return false;
    }

    // This function is called when an error callback parses the JSON response
    // It is a public function because the error callback occurs within the onreadystatechange
    // event handler and an internal function would not be in scope.
    this.errorHandler = function (resp) {
        try {
            return JSON.parse(resp).error;
        } catch (e) {
            return new Error("Unexpected Error")
        }
    }

    this.dateReviver = function (key, value) {
        ///<summary>
        /// Private function to convert matching string values to Date objects.
        ///</summary>
        ///<param name="key" type="String">
        /// The key used to identify the object property
        ///</param>
        ///<param name="value" type="String">
        /// The string value representing a date
        ///</param>
        var a;
        if (typeof value === 'string') {
            a = /^(\d{4})-(\d{2})-(\d{2})T(\d{2}):(\d{2}):(\d{2}(?:\.\d*)?)Z$/.exec(value);
            if (a) {
                return new Date(Date.UTC(+a[1], +a[2] - 1, +a[3], +a[4], +a[5], +a[6]));
            }
        }
        return value;
    }

}).call(bd_Utilities.WebAPI);