By the end of this week you will have created a functional DevMountain social network that allows you to connect with other students and graduates. Along the way you will learn the core concepts of AngularJS, as well as learning how to access outside APIs for data.
To start things off we first need to include the Angular source code in our index.html. You can find this at https://cdnjs.com/libraries/angular.js . Scroll down until you see https://cdnjs.cloudflare.com/ajax/libs/angular.js/_VERSIONNUMBER_/angular.js and copy that link into a script tag at the bottom of your <body>.
Now that we have included the Angular script, our next step is to set up the bones of our first Angular application. The first step is to create an app.js file. Inside this file we need to initialize our new Angular app which we will call 'devMtIn'.
angular.module('devMtIn', []);Be sure to include your app.js file in your index.html underneath the Angular script. If included above the Angular script, the app will not function. Our last step in including Angular in our new app is to add the ng-app attribute to our HTML. This attribute should be added to our <html> tag and should reference the name of our app. <html ng-app="devMtIn">.
Now we are ready to launch our app using http-server or live-server. You should see the page laid out with the included HTML and CSS. Check the console to make sure there are no errors.
Now that Angular is up and running, let's actually do something with it. For this, we need a controller. A controller is the glue that Angular uses to connect your code to the view. To create our controller, let's create another new file called homeCtrl.js.
Inside of homeCtrl.js we will need to create a new controller on an angular.module, give that controller a name, and pass in a callback function that takes in the $scope parameter.
angular.module('devMtIn')
.controller('homeCtrl', function($scope) {
});Remember that we don't want to pass our angular.module an array here! When you pass in an array, you are making an entire new app rather than looking for your current one. Now all we need to do is include the script in a new script tag and add the ng-controller attribute to our <body> tag and pass it "homeCtrl".
To test that everything is working so far, create a property on your $scope called 'myProfile' and set it equal to an object containing name: _YOUR NAME_. Inside of your HTML replace the header 'Your Name' with {{ myProfile.name }}. If everything is working you should see your name at the top of the page.
What you've just done in the above step is called data binding, we are binding the information inside of our controller to our view using the handlebars ({{ }}) notation. This binding can handle more than just displaying static data, it can also process simple evaluations.
To demonstrate this let's change our HTML name header to this: {{ myProfile.name || 'Your Name' }}. Now if you set myProfile.name to an empty string in your controller you will see the page is displaying the string 'Your Name' instead of the value of myProfile.name.
Let's add some data to repeat over, add a new property to your myProfile object named 'friends'.
$scope.myProfile = {
name: 'John Doe'
, friends: [{name: 'Ryan'}, {name: 'Bryan'}, {name: 'Sarah'}, {name: 'Zac'}, {name: 'Erin'}]
}To repeat over this data we need to add an ng-repeat directive as an attribute to our <div class="friendList" and tell it to repeat over each 'friend' in myProfile.friends. Then inside of that div, in place of 'My Friends' we need to bind each friend to our view.
<div class="friendList" ng-repeat="friend in myProfile.friends">
<span class="closeBtn"></span>
{{ friend.name }}
<br>
<div class="secondConnection friendList">
My Second Connections
</div>
</div>Once you refresh the page you should see a list of your current friends' names.
So far we have bound data to our view from our controller, but there is no interactivity. None of our input boxes or buttons do anything, and all of our data is static on our controller. To begin to change that we need to utilize Angular's built in ng-model directive.
What ng-model does is create a two way data-binding from our controller to our view. This means that any changes made to the data by either the controller or the user will be reflected in both places. To demonstrate this, let's add an ng-model attribute on our 'name' input box and pass it the value myProfile.name. Inside of your controller, delete the name property of myProfile.
Once you refresh the page, try typing your name into the input box you adjusted. You should see the header update as you type. What Angular is doing here is looking at your $scope.myProfile object, seeing that it doesn't contain a name property, and so creating that property for us.
Now we have some interactivity! Let's take it a step further by using ng-model to filter our data. To do this we will need to add a new ng-model to our 'Find Friends' input box named 'findFriend.name'. Angular will create the findFriend object on our $scope and assign the new property name to whatever value is inside the input box.
To use this to filter data takes only one more step. Inside of the friend list ng-repeat attribute add a new filter and pass it the value of findFriend.name. This should look something like this:
<div class="friendList" ng-repeat="friend in myProfile.friends | filter : findFriend.name">After refreshing the page you should now be able to type into the 'Find Friends' box and see your friends' list filter in real time.
We want our users to be able to choose whether they want to sort their friends in ascending or descending order. To do this we will be using Angular's ng-options directive. ng-options works similarly to ng-repeat but creates a select box with dynamically generated options instead of repeating an element.
Before adding this directive to our HTML we need to create an array on our controller to give ng-options something to loop over. This will be an array of two objects containing a select value and a display value. It should look something like this:
$scope.sortOptions = [{
display: 'Ascending'
, value: false
},
{
display: 'Descending'
, value: true
}
];Remember that display and value are just key names; they can be named whatever you like as long as you adjust the HTML accordingly.
Next we will need to add a select element into our index.html just below our search bar. The syntax for ng-options is very similar to ng-repeat with some extras added on. It will look like this:
<select ng-model="sortReverse" ng-options="option.value as option.display for option in sortOptions"></select>The syntax is a little odd, but what we are saying is that option.value will be the value we use for every option.display in our sortOptions array. It is also important to notice that I've included an ng-model on the new select element. ng-options will not work at all without an ng-model to pass its data to.
To add this logic to our filter we only need to pass our ng-repeat a new filter called orderBy. The first argument passed to orderBy is the property we wish to sort on. The second is a boolean that tells orderBy whether or not we wish to reverse the array.
<div class="friendList" ng-repeat="friend in myProfile.friends | filter : findFriend.name | orderBy : 'name' : sortReverse">Well done! You've finished your first day of AngularJS, and now you have the knowledge to allow users to interact with the $scope, repeat over data, filter data, bind data to the DOM, and dynamically generate select elements using ng-options.
To begin day two we need to start by creating a new file named profileService.js. This file will have an initial setup very similar to our homeCtrl.js. We need to invoke the service method on an angular.module and pass that method the name of our service and a callback function.
angular.module('devMtIn')
.service('profileService', function() {
});An important distinction between services and controllers is that services do not take in the $scope parameter. Services will have no direct link to the view--their primary purpose is to do the heavy lifting for the rest of the application and pass data to controllers.
Let's add a simple test function onto this service. This function should simply console.log 'profileService is connected!'. Remember that when creating properties in a service you use the this keyword.
this.serviceTest = function() {
console.log('profileService is connected!');
}To make use of this function inside of our homeCtrl we need to add the service script to our index.html and inject our profileService the same way we injected $scope yesterday.
angular.module('devMtIn')
.controller('homeCtrl', function($scope, profileService) {
//…We can now access our serviceTest function by simply prefixing the function name with the name of our service and invoking it, profileService.serviceTest(). Once you refresh the page you should see the message inside of your console.
Yesterday we started with some basic user interactivity using ng-model and ng-options. Today we're going to go further by introducing ng-click, Angular's built in click handler directive.
For our first ng-click we'll start with a simple expression that disables profile editing unless the editing button is clicked. Begin by creating $scope.editing in your homeCtrl and setting its value to false.
To disable our form fields we need to use another built-in Angular directive, ng-disabled. ng-disabled simply evaluates the expression passed to it and disables its containing element based on the truthiness or falsiness of the expression. Add ng-disabled as an attribute to the three profile inputs and pass them !editing. Once you refresh the page the profile form fields should now be disabled.
Now that we have our ng-disabled working, we just need to flip the value of editing anytime a user clicks on the editing button. To do this we need to add the ng-click attribute to our 'Editing' button and pass it editing = !editing. One last step for clarity: we should display the value of editing inside of the 'Editing' button to make it clear whether or not editing is active.
Once that is complete you should be able to lock and unlock the profile fields, displaying whether or not they are editable in the 'Editing' button.
The next step will be to set up local storage, letting our profiles persist between refreshes. We'll start in the html and work back to the service.
The first thing we need to do is add ng-models to the rest of our profile fields. Make sure these ng-model's point to new properties on the myProfile object. Next, we will need an ng-click on the profile's 'Save' button. This ng-cick should invoke a function we will create on our controller named saveProfile and pass it myProfile as the only argument. This is all we need in our HTML. Next step: controller.
In homeCtrl.js create the saveProfile function and make sure it accepts a profile parameter. This function should simply call profileService.saveProfile, passing in the profile parameter as an argument, then set $scope.editing to false. It may seem odd to have a function who's only job is to pass data from the view to a service, but remember that the primary use of controllers is to act as a sort of middle-man. Controllers exist to communicate between the view and the services.
We now need to create a saveProfile function inside of profileService. This function should also take a profile parameter and save that profile object to local storage. The function will look something like this:
this.saveProfile = function(profile) {
localStorage.setItem('profile', JSON.stringify(profile));
}To make sure this is working enter console.log(localStorage.profile) in your browser's console. You should see your profile information print to console, even after refreshing.
Our profile is saving, but isn't yet returning to the view on page reloads. Let's fix that.
To start, we'll create a new function inside of profileService.js named checkForProfile. This function will check local storage and return the profile if it exists, otherwise returning a default friends list.
this.checkForProfile = function() {
if (localStorage.getItem('profile')) {
return JSON.parse(localStorage.getItem('profile'));
}
return {
friends: [{name: 'Ryan'}, {name: 'Bryan'}, {name: 'Sarah'}, {name: 'Zac'}, {name: 'Erin'}]
}
}Now inside of homeCtrl.js instead of setting $scope.myProfile equal to a friends list, we can set it equal to profileService.checkForProfile(). Now your profile should load automatically on page refresh.
The last step for today will be adding functionality to our delete button. This will follow the same basic steps as adding to local storage.
Add an ng-click to the 'Delete' button that calls a deleteProfile function inside of our controller. Our controller should call a profileService.deleteProfile function that simply removes the profile from local storage (localStorage.removeItem('profile')). After deleting the profile, we need to get our basic friends list back, so set $scope.myProfile equal to profileService.checkForProfile() again.
You've completed Angular day two! Now you know how to create services, access services inside of your controllers, handle clicks, and save to local storage.
Yesterday we stored our profiles in local storage, allowing them to persist between refreshes. Today we want to add our profile to a database, letting other users find and connect with us.
Before we start writing our new code, let's make some adjustments. Delete the array of friends from the profileService.checkForProfile function and run localStorage.removeItem('myProfile') in your console so we can start fresh.
To begin, we need to inject Angular's built in $http service into our profileService. $http will allow us to make HTTP requests for any CRUD operation (Create, Read, Update, Delete). We will also need to create a variable named baseUrl and set it equal to http://connections.devmounta.in/
We're going to adjust our saveProfile function inside of profileService. Now instead of saving our whole profile to local storage, we want to post it to the database, and just save the unique _id the database sends back to us. Let's delete everything we currently have inside of the function and start from scratch.
Our updated saveProfile function will make an HTTP request with the method of 'POST', data of profile, and a url of baseUrl + '/api/profiles'. It should look something like this:
this.saveProfile = function(profile) {
return $http({
method: 'POST' // Request method.
, url: baseUrl + 'api/profiles/' // URL we are making the request to.
, data: profile // The data we are requesting be posted.
})
}We will also want to add a .then method to the end of our $http request. .then takes in a callback function as an argument, and that callback function will take in a profileResponse parameter. Inside of our callback function we now want to set localStorage.setItem('profile', JSON.stringify({ profileId: profileResponse.data._id }));, then catch any errors. The end result will look like this:
this.saveProfile = function(profile) {
return $http({ // Requests that your profile be added to the database
method: 'POST'
, url: baseUrl + 'api/profiles/'
, data: profile
})
.then(function(profileResponse) { // What to do after a response comes back from the server.
localStorage.setItem('profileId', JSON.stringify({ profileId: profileResponse.data._id })); // Save our unique _id to local storage
})
.catch(function(err) {
console.error(err);
});
}I also recommend a console.log(profileResponse) inside of your .then callback to see exactly what data the server is sending back to you.
Our profile is now saving to the server, but we never retrieve it, and local storage is only saving our id. Let's fix this.
To make this work we're going to change our profileService.checkForProfile function. Just like before, let's delete what we currently have inside the function and start fresh. This updated function will take in a profileId parameter. All the function needs to do is return an HTTP request with the method of 'GET' and a URL of baseUrl + '/api/profiles' + profileId.
this.checkForProfile = function(profileId) {
return $http({
method: 'GET'
, url: baseUrl + 'api/profiles/' + profileId
});
}For this to work we will also need to adjust our homeCtrl. Remove the line where we set $scope.myProfile equal to profileService.checkForProfile and create a new function named $scope.checkForProfile.
$scope.checkForProfile will first pull our profileId from local storage and save it to a variable named profileId. Next it will need to check whether or not profileId exists. If profileId exists, we will want to invoke profileService.checkForProfile and call the .then method. Inside of the callback function for .then we will want to set $scope.myProfile equal to the response from our callback function, then .catch any errors.
The final function should look like this:
$scope.checkForProfile = function() {
var profileId = JSON.parse(localStorage.getItem('profileId'));
if (profileId) {
profileService.checkForProfile(profileId.profileId)
.then(function(profile) {
$scope.myProfile = profile.data;
})
.catch(function(err) {
console.error(err);
});
}
}The last step here is to invoke your $scope.checkForProfile function immediatly after declaring it.
You should now be able to create and retrieve your profile from the remote server.
The last update to have all of our previous functionality working with a remote server is to update our profile deleting functions. As we have before, let's clear out our profileService.deleteProfile function and start fresh.
Our fresh deleteProfile function will need to retrieve our profileId from local storage, then return an HTTP request with a method of 'DELETE' to the URL baseUrl + 'api/profiles/' + profileId.
this.deleteProfile = function() {
var profileId = JSON.parse(localStorage.getItem('profileId')).profileId;
return $http({
method: 'DELETE'
, url: baseUrl + 'api/profiles/' + profileId
});
}With that done, we need to update our homeCtrl. All we need to do here is add a .then to our current profileService.deleteProfile() call that removes the profileId from local storage and sets $scope.myProfile equal to an empty object.
$scope.deleteProfile = function() {
profileService.deleteProfile()
.then(function(deletedProfile) {
localStorage.removeItem('profileId');
$scope.myProfile = {};
})
.catch(function(err) {
console.error(err);
});
}Our app is now functional in all of the basic steps of creating, saving, retrieving, and deleting our profile on a remote server. Tomorrow we will cover promises, $q, and finding and adding friends.
So far our social network is lacking a social aspect. Today we will add the functionality to find and add friends and second-level friends.
To begin finding friends we'll want to create a new service named friendService. We are going to be handling all of our friend adding and searching from this service. The reason we are using a new service rather than extending our current service is because it is generally a good idea to keep services as singularly focused as possible.
Inside of this new service we need to inject $http, create the same baseUrl variable as we have in our profileService, and create a findFriends function that takes in a userId and query parameter. This function will return an HTTP request with a method of 'GET' and a url of baseUrl + '/api/friends/' + userId + '?name=' + query.
Now we need to inject friendService into our homeCtrl and create a new function named findFriends that takes in a query parameter and invokes friendService.findFriends, passing in $scope.myProfile._id and query. We will also need to add a .then method to the end of friendService.findFriends that sets $scope.potentialFriends equal to the response.
Since our list of potential friends is now on the $scope, we can display it in the view. Inside of the friends list div that contains 'Potential Friends' add an ng-repeat to the span element and pass it our array of potential friends. Next, bind each friend's name to the HTML.
All that's left to do to display our list of potential friends is to add an ng-click directive to the 'Go' button and pass it our findFriend function, passing in findFriend.name as the query.
We will also want to be able to add friends, which means creating a new function inside our friendService. We'll name this function addFriend. It will need to take in userId and friendId parameters. addFriend will return an HTTP request with the method of 'PUT', to the url baseUrl + '/api/friends/' + userId, with a data object of { friendId: friendId }.
We will need a function in our controller to access friendService.addFriend. I'll name mine $scope.addFriend. This function will take in a friendId parameter and call friendService.addFriend passing in $scope.myProfile._id and friendId. Inside of a .then method run $scope.checkForProfile to retrieve our updated profile.
The last step in adding friends will be to attach this function to our view. Let's add a new button inside of our potential friends ng-repeat with an ng-click that invokes the addFriend function passing in friend._id.
You are now able to succesfully search and add friends!
Let's add the functionality to remove friends as well. This will be very similar to our addFriend function. It will return an HTTP request with a method of put, a url of baseUrl + '/api/friends/remove/' + userId, and a data object of { friendId: friendId }.
We'll need to attach this to a function in homeCtrl that takes in a friendId parameter and invokes friendService.removeFriend passing in $scope.myProfile._id and friendId. In the .then method we simply need to invoke $scope.checkForProfile to update our profile.
Now attach this function to a view via an ng-click on the span element with a class of closeBtn inside of our friends list ng-repeat.
Our next step is going to be finding second level connections. To do this we will need to use $q. Yesterday we became accustomed to using the .then method on our HTTP requests. What .then is doing is handling the promise returned from the HTTP request. Because these requests are asynchronous .then is called when the promise is resolved, letting the rest of our code continue running. $q exists to create our own promises when necessary.
We'll start by injecting $q into our friendService. We're going to be using it to search for second level friends. To do this we'll need a new function: findFriendsFriends. This function will take in a single profile argument.
Inside this function we need to declare an index variable and set it equal to 0. We will also create our first promise with $q. To do this we create a new variable named deferred and set it equal to $q.defer().
We will be making use of a closure to process our friends list, so we are going to declare a new function inside of the findFriendsFriends named getNextFriend. In this getNextFriend function we first need to check whether or not our profile has a friend at the current index. So far our function should look something like this:
this.findFriendsFriends = function(profile) {
var index = 0; // Create an index that we will use to track friends.
var deferred = $q.defer(); // Create a promise and assign it to the variable deferred
function getNextFriend() { // Declare a closure function.
if (profile.friends[index]) { // Check to see if there are friends remaining in the array
//...
}Inside of this if statement we need to make an HTTP request with a method of 'GET', and a url of baseUrl + '/api/friends-friends/' + profile.friends[index]._id.
Our .then method on this request will take in a friends parameter and assign it to profile.friends[index].friends = friends.data;, then increment index, and finally call getNextFriend. Don't forget to add an error handler after .then! Here's what we have so far:
this.findFriendsFriends = function(profile) {
var index = 0;
var deferred = $q.defer();
function getNextFriend(){
if (profile.friends[index]) {
$http({ //Our API request
method: 'GET'
, url: baseUrl + '/api/friends-friends/' + profile.friends[index]._id
})
.then(function(friends) { //Taking in an array of friends returned from the server.
profile.friends[index].friends = friends.data; // Update our friend with the recieved data.
index++; // Increment our counter.
getNextFriend(); // Recall the function to handle the next friend.
})
.catch(function(err) { // Error Catching
return console.error(err);
});To finish this function we need to add an else that will run deferred.resolve(profile) and then return deferred.promise. The last step is adding a function call to the end of our outer function. Here is the final version. Try to read through it several times to ensure you understand everything that is going on.
this.findFriendsFriends = function(profile) {
var index = 0;
var deferred = $q.defer();
function getNextFriend() {
if (profile.friends[index]) {
$http({
method: 'GET'
, url: baseUrl + '/api/friends-friends/' + profile.friends[index]._id
})
.then(function(friends) {
profile.friends[index].friends = friends.data;
index++;
getNextFriend();
})
.catch(function(err) {
return console.error(err);
});
} else { // Once we have finished running through our friends array
deferred.resolve(profile); // Resolve our promise with our updated profile
return deferred.promise; // Return the promise
}
}
getNextFriend(); // Invoke the inner function for the first time
}All that is left is to call our new function. I will be adding the function call inside of homeCtrl's $scope.checkForProfile function, inside of the .then.
$scope.checkForProfile = function() {
var profileId = JSON.parse(localStorage.getItem('profileId'));
if (profileId) {
profileService.checkForProfile(profileId.profileId)
.then(function(profile) {
$scope.myProfile = profile.data;
friendService.findFriendsFriends(profile.data); // Finding second level friends.
})
.catch(function(err) {
console.error(err);
});
}
}Now whenever your code checks for your profile it will also update second level friends.
You've completed your first week of Angular! Congratulations! Just today you created your own promise and implemented a recursive, closure scoped function!
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