Learn Development at Frontend Masters. If you are new to React, and perhaps have only played with building to-do and counter apps, you may not yet have run across a need to pull in data for your app.
The first set of data you may need to handle might be hard-coded into your React application, like we did for this demo from our Error Boundary tutorial :.
What if you want to handle data from an API? The Fetch API provides an interface for fetching resources. There is bound to be a delay when data is being requested by the network.
Creating ASP.NET Apps with React
It could be a few seconds or maybe a few milliseconds. The data will be displayed when isLoading is falseelse a loading message will be shown on the screen. So the render method will look like this:. For Steps to work, we need to make the request to fetch data from an API. We create a method called fetchUser and use it to do exactly what you might think: request user data from the API endpoint and fetch it for our app.
Fetch is a promise-based API which returns a response object. So, we make use of the json method to get the response object which is stored in data and used to update the state of users in our application. We also need to change the state of isLoading to false so that our application knows that loading has completed and all is clear to render the data. The fact that Fetch is promise-based means we can also catch errors using the.
We want to trigger the method to fetch the users when the application state can be accessed for an update and the application re-rendered. You can see the difference between our data structure here and the one we obtained from JSONPlaceholder.
When isLoading is not truewe return an array, map through it and pass the information to the Post component as props. Very similar to before. Now we can call the fetchPosts method inside a componentDidMount method. In the Post component, we map through the props we received and render the title and content for each post:.
There we have it! Now we know how to use the Fetch API to request data from different sources and put it to use in an application. High fives. Like the Fetch API, axios is a way we can make a request for data to use in our application.GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together. If nothing happens, download GitHub Desktop and try again.
If nothing happens, download Xcode and try again. If nothing happens, download the GitHub extension for Visual Studio and try again. This project was bootstrapped with Create React App. Below you will find some information on how to perform common tasks. You can find the most recent version of this guide here. You almost never need to update create-react-app itself: it delegates all the setup to react-scripts.
In most cases bumping the react-scripts version in package. We commit to keeping the breaking changes minimal so you can upgrade react-scripts painlessly. We are always open to your feedback. You may create subdirectories inside src. For faster rebuilds, only files inside src are processed by Webpack. You can, however, create more top-level directories. They will not be included in the production build so you can use them for things like documentation. Runs the app in the development mode.
Launches the test runner in the interactive watch mode. See the section about running tests for more information. Builds the app for production to the build folder. It correctly bundles React in production mode and optimizes the build for the best performance. The build is minified and the filenames include the hashes.
Your app is ready to be deployed! Note: this is a one-way operation. This command will remove the single build dependency from your project. Instead, it will copy all the configuration files and the transitive dependencies Webpack, Babel, ESLint, etc right into your project so you have full control over them.
All of the commands except eject will still work, but they will point to the copied scripts so you can tweak them. To configure the syntax highlighting in your favorite text editor, head to the relevant Babel documentation page and follow the instructions. Some of the most popular editors are covered.
They are not required for linting. You should see the linter output right in your terminal as well as the browser console. However, if you prefer the lint results to appear right in your editor, there are some extra steps you can do. If you are using the Atom linter-eslint plugin, make sure that Use global ESLint installation option is checked:.React also prefers yarn if you have it installed. You can install those both with this command:.
The script will create a new directory with some starter files, install a slew of dependencies needed to get things up and running and initialize the project with git. You can now change into the directory and start the development server, which will open the app in your web browser. Your browser will automatically update whenever you change any source files.
Since this will be showing Chuck Norris jokes, find your favorite image of Chuck Norris or just use the one below. If you used the image above, the default dark background will make it hard to see.
You can get rid of the animation line and you can get rid of the keyframes block. In the end, your CSS should look something like this I also added a little padding to the header for small screens :.
With the release of React The default looks something like this:. Change the line importing React to look like this:. Then to use a piece of state, add the following to the top of your App function, before the return statement :. You now have a way to read a joke and change its value. By default, it will just be an empty string until you fetch it. Install it using:. Since this will need to reference setJokeit should be written inside the App component. The fetch API supports a signal that will allow you to cancel the call.
This would be important to make sure calls come back in the right order. The useEffect hook will run any time the component renders. However, you can add an array of values to watch, which will cause it to only run the effect when one of those values changes.
If the effect has a return value, it will be run when cleaning up the app, or before rendering again. Here is where you can provide a function that will cancel the fetch call. Now you just need to display the joke and add a button to fetch a new one. Clicking the button will set the joke back to an empty string, and the effect will take care of fetching a new joke. Now that you have a functional web app, you can add some personalization by allowing users to sign in.
Our API enables you to:. Log in to your developer console, navigate to Applicationsthen click Add Application. Select Single-Page Appthen click Next.
Your settings should look like the following:. Click Done to save your app, then copy your Client ID and paste it as a variable into a file called.
This will allow you to access the file in your code without needing to store credentials in source control. You may need to restart your server before it will recognize these changes. You can find the running instance and then hit ctrl-c to close it.
To do this, the article covers building a CRUD application of user data, exploring the construction of both back and front ends, from the installation and configuration to the implementation. This is the final representation of the view, once done:. First, make sure you have a recent version of Visual Studio Community installed on your computer. Give it a name and click OK. NET Core projects. This will lead you a better understanding of the basics around how React works, as well as how you will connect the front to the back-end API.
Additionally, this example will not use the same structure VS sets up there. It consists of a project in which the front will be hosted the same place as the back-end code. Nevertheless, you will work in a side front project independent of the ASP. NET suite. Once finished, move on to the ASP. Make sure to create each folder in the root source folder.
Start with the User. Listing 1 shows its content. There are a couple of new things going on. First, you need a static List to store the elements, simulating something like a database feel free to implement whatever storage strategy you would like. The next three arrays represent some random names, surnames and mail extensions in order to facilitate the process of generating a prelist of users and randomize their field values as well.
The static block initializes this list, making sure to generate as many random values as possible.es7unstop.pw Hooks Crash Course
The rest of the methods are just performing usual operations over the list, with the help of Linq. Time to move to the controller. Make sure to rename the default one already created to UsersController. Then, substitute its content with the code shown in Listing 3.
However, some things are noticeable:. Finally, you need to make some important configurations to the Startup.React is the one of the most popular frontend framework out there and more developers are increasing learning how to build real life applications with React.
While learning React, you will eventually get to a point when you need to integrate APIs in your React application. We will be building a simple contact list application to display the contact's name, email and we will store a catch phrase of a contact.
Fetching API Data with React.JS
We will make use of this endpointit contains a JSON dump of data needed for our contact list application. We will be creating our React Application using a neat tool called create-react-appthis is a boilerplate that helps you set up a proper folder structure and assets binding for your React application.
Run this command on your terminal. Next, we will create a new project using create-react-app.
So you can switch into your preferred directory and run this command on your terminal. This will generate some scaffolds you need to get your React application running as quick as possible. The next step is to modify the App. If you noticed, we got rid of import logo from '. Next, we have to link bootstrap's CDN in the index. When this is done we will render a bootstrap card in the App. If we reload our application the following changes will reflect showing the contact's name, email and catch phrase in a bootstrap card.
Our application will parse and display the data in a presentable manner, making it appealing to the user. Below is a typical JSON response from the contact list dump :. A state is simply an object that holds data pending to be rendered.
This is where we will store the output from the API call. To fetch our contact list, we will use a componentDidMount method in our App.
This method is executed immediately our component is mounted and we will also make our API request in that method. Next up, we will create a component to render the results as cards. To achieve this we will create a component by creating a new sub-folder named components in the src directory followed by creating a contacts.
The Contacts method accepts the contacts state we created earlier and then returns a mapped version of the state, which loops over the bootstrap card to insert the contact's nameemail and catch phrase. To do this, we have to import the component into App. Then in our render method we have to clear out whatever we had there before and pass our component along with the contacts state in there for it to be rendered. If you don't already have your application running, you can run it by using the npm start command.
Now we get into actual Fetch API:. Let's review this code, shall we? Then we get a response but the response we get is not JSON but an object with a series of methods we can use depending on what we want to do with the information, these methods include:. Now let's get to the part we create the list items, for that, I created two helper functions at the top of my file just to make the code simpler down the line:. All these functions do is append and create elements as you can see.
Once this is done we can move on to the resolution of our promise and add the code we need to append these list items to our unordered list:. So first we define authors as the response we get from the request then we map over all the authors and for each we create a list item, a span, and an image.
To handle our catch all I will do is console log the error as we get it but you can do whatever you want with the error such as append it to the HTML with the functions we created. This is the full code of our little request:. So this is a GET request, the default one for the fetch function but of course we can do all other types of requests and also change the headers and off course send data, all we need for this is to set our object and pass it as the second argument of the fetch function:.
You can also define cache, mode and all those things you are used to defining in your POST requests. To create our object and use the fetch function we also have another option and that is to use the request constructor to create our request object, so instead of defining the object in the function itself we do this:.
There are also polyfills if you really want to use it in more professional projects. Like this article? How do we use the Fetch API? Handling more requests like POST. Read nextOver the years, building web applications that are mobile friendly has become easier with the advent of media queries and the introduction of service workers.
You can follow the official React tutorial here to get up to speed with React. The babel-plugin-module-resolver is a plugin that resolves your project modules when compiling with Babel. Expo is an open-source toolchain built around React Native for building Android and iOS applications. Run the command below to install the packages:. After downloading the packages needed to run and build the application, the next step is to setup the configuration files.
Create a file called. Create a file named app.
Create user Registration and Login using Web API and React
You can find the options available for the app. This file will act as the entry file for the expo-cli. Open the package. Our application is a simple demo that displays users via the random user API. Open this file using an editor and update it with the snippet below:. Currently, the component displays an ActivityIndicator ; this will be replaced by the user list when the call to the API is complete. We create styles for the elements using the StyleSheet component.
This allows us to style the component using properties similar to CSS properties.