How to “$http calls to RESTful APIs”? And how do “CRUD Operations RESTful API” in AngularJs?
In this post, I am going to demonstrate about how can we create basic CRUD (CREATE, READ, UPDATE, DELETE) Operations in AngularJs using RESTful APIs and Entity Framework.
The $http Services is use to invoke RESTful APIs (GET, POST, PUT, DELETE) and in the below source code, we will use the responses from RESTful APIs to refresh the page data.
In AngularJs, by default uses asynchronous HTTP calls. So that we can use two callback methods that is successCallback() and other is errorCallback(), which will be invoked by angular after a response is returned from server.
Table of Contents:-
1. RESTful APIs - GET Operation
2. RESTful APIs - POST Operation
3. RESTful APIs - PUT Operation
4. RESTful APIs - DELETE Operation
Let’s start step by step so that we can achieve our CREATE, READ, UPDATE, DELETE Operations.
1) RESTful APIs - GET Operation: -
In Angular $http Services is used to invoke HTTP GET API and we will get the employee list and bind the page.
Source Code -
$http({
method: 'GET',
url: 'http://localhost:8080/api/GetEmployees'
}).then(successCallback, errorCallback);
//success callback method.
var successCallback = function (response) {
$scope.employees = response.data.employees;
};
//error callback method.
var errorCallback = function (response) {
alert(response.statusText);
}
2) RESTful APIs - POST Operation: -
In Angular $http Services is used to invoke HTTP POST API and we will Add an employee using the services,
Source Code -
$http({
method: "POST",
url: "http://localhost:8080/api/AddEmployee",
data: angular.toJson($scope.form),
headers: {
"Content-Type": "application/json"
}
}).then(success, error);
//success callback method.
var success = function (response) {
if (response.data.status == 'Ok') {
alert(response.statusText);
}
};
//error callback method.
var error = function (response) {
if (response.data.status == 'error') {
alert(response.statusText);
}
};
3) RESTful APIs - PUT Operation: -
In Angular $http Services is used to invoke HTTP PUT API and we will update an employee using the services,
Source Code -
$http({
method: "PUT",
url: "http://localhost:8080/api/UpdateEmployee/" + $scope.form.id,
data: angular.toJson($scope.form),
headers: {
"Content-Type": "application/json"
}
}).then(success, error);
//success callback method.
var success = function (response) {
if (response.data.status == 'Ok') {
alert(response.statusText);
}
};
//error callback method.
var error = function (response) {
if (response.data.status == 'error') {
alert(response.statusText);
}
};
4) RESTful APIs - DELETE Operation:-
In Angular $http Services is used to invoke HTTP Delete API and we will Delete an employee using the services,
Source Code -
$http({
method: "DELETE",
url: "http://localhost:8080/api/DeleteEmployee/" + employee.id
}).then(success, error);
//success callback method.
var success = function (response) {
if (response.data.status == 'Ok') {
alert(response.statusText);
}
};
//error callback method.
var error = function (response) {
if (response.data.status == 'error') {
alert(response.statusText);
}
};
Examples – CRUD Operations using RESTful APIs,
<!doctype html> <html> <head> <meta charset="utf-8" /> <title> AngularJS REST APIs using $http Services </title> <script src="http://ajax.googleapis.com/ajax/libs/angularjs/1.4.8/angular.min.js"></script> <script> var app = angular.module("employeesMgmt", []); //Controller Part app.controller("employeesMgmtController", ["$scope", "$http", function ($scope, $http) { //Initialize page with default data which is blank in this example $scope.employees = []; $scope.form = { id: -1, empFirstName: "", empLastName: "", empEmailID: "" }; //GET & BIND THE EMPLOYEE LIST FROM SERVER. getEmplyees(); //HTTP GET- GET ALL EMPLOYEES COLLECTION. //SUCCESS CALLBACK METHOD. var successCallback = function (response) { if (response !== undefined && response.data.status === 'Ok') { $scope.employees = response.data.employees; } }; //ERROR CALLBACK METHOD. var errorCallback = function (response) { if (response !== undefined && response.data.status === 'Ok') { alert(response.data.statusText); } } //GET EMPLYEES API CALLs. var getEmplyees = function () { $http({ method: 'GET', url: 'http://localhost:8080/api/GetEmployees' }).then(successCallback, errorCallback); }; //SUCCESS HANDLER FOR ADD/UPDATE AND DELETE EMPLOYE var success = function (response) { if (response !== undefined && response.data.status === 'Ok') { getEmplyees(); } }; var error = function (response) { if (response !== undefined && response.data.status === 'error') { alert(response.statusText); } }; //HTTP POST/PUT METHODS FOR ADD/UPDATE EMPLOYEE. $scope.addUpdateEmployee = function () { var methodType = "", apiURL = ""; if ($scope.form.id == -1) { methodType = "POST"; apiURL = 'http://localhost:8080/api/AddEmployee'; } else { //IF ID IS PRESENT, IT'S EDIT OPERATION - PUT OPERATION methodType = "PUT"; apiURL = 'http://localhost:8080/api/UpdateEmployee/' + $scope.form.id; } //HTTP POST & PUT API CALLs. $http({ method: methodType, url: apiURL, data: angular.toJson($scope.form), headers: { 'Content-Type': 'application/json' } }).then(success, error); }; //HTTP DELETE API CALL- DELETE EMPLOYEE BY ID $scope.deleteEmployee = function (employee) { $http({ method: 'DELETE', url: 'http://localhost:8080/api/DeleteEmployee/' + employee.id }).then(success, error); }; //IN CASE OF UPDATE EMPLOYEE & POPULATE FORM WITH EMPLOYEE DATA. $scope.updateEmployee = function (employee) { $scope.form.empFirstName = employee.empFirstName; $scope.form.empLastName = employee.empLastName; $scope.form.empEmailID = employee.empEmailID; $scope.form.id = employee.id; }; }]); </script> </head> <body ng-app="employeesMgmt" ng-controller="employeesMgmtController"> <h1>AngularJS - Use $http to invoke RESTful APIs</h1> <table style="width:100%;"> <tr> <th>First Name</th> <th>Last Name</th> <th>EmailID</th> <th>Actions</th> </tr> <tr ng-repeat="emp in employees"> <td style="width:25%;">{{ emp.empFirstName }}</td> <td style="width:25%;">{{ emp.empLastName }}</td> <td style="width:25%;">{{ emp.empEmailID }}</td> <td style="width:25%;"><a ng-click="updateEmployee(emp)" class="button">Edit</a> | <a ng-click="deleteEmployee(emp)">Delete</a></td> </tr> </table> <h2 style="color:green;">Add/Update Employee</h2> <form ng-submit="addUpdateEmployee()"> <table> <tr> <td>First Name</td> <td><input type="text" ng-model="form.empFirstName" size="60" /></td> </tr> <tr> <td>Last Name</td> <td><input type="text" ng-model="form.empLastName" size="60" /></td> </tr> <tr> <td>empEmailID</td> <td><input type="text" ng-model="form.empEmailID" size="60" /></td> </tr> <tr> <td colspan="2"><input type="submit" value="Submit" /></td> </tr> </table> </form> </body> </html>
Restful APIs Source Code -
using MongoDemoApp.API; using System.Linq; using System.Web.Http; namespace AngularJsDemoApp.API { public class EmployeeController : ApiController { DataContext dbContext = new DataContext(); /// <summary> /// USED FOR GET EMPLOYEE LIST. /// </summary> [HttpGet] public Employee GetEmployees() { Employee emp = dbContext.Employee.ToList(); return emp; } /// <summary> /// USED FOR BIND UPDATE EMPLOYEE POPUPS. /// </summary> [HttpGet] public Employee GetEmployees(int id) { Employee emp = dbContext.Employee.Find(id); return emp; } /// <summary> /// USED FOR ADD EMPLOYEE. /// </summary> [HttpPost] public int AddEmployee(Employee emp) { dbContext.Employee.Add(emp); dbContext.SaveChanges(); return emp.UserId; } /// <summary> /// USED FOR UPDATE EMPLOYEE. /// </summary> [HttpPut] public void UpdateEmployee(Employee emp, int id) { if (emp.EmpId == id) { dbContext.Entry(emp).State = EntityState.Modified; dbContext.SaveChanges(); } } /// <summary> /// USED FOR DELETE EMPLOYEE. /// </summary> [HttpDelete] public void DeleteEmployee(int id) { Employee emp = dbContext.Employee.Find(id); if (emp != null) { dbContext.Employee.Remove(emp); dbContext.SaveChanges(); } } } }
Other References,
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Anil Singh is an author, tech blogger, and software programmer. Book writing, tech blogging is something do extra and Anil love doing it. For more detail, kindly refer to this link..
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