Apollo state management in Vue application

Apollo state management in Vue application

<strong>Originally published by </strong><a href="https://dev.to/n_tepluhina" target="_blank">Natalia Tepluhina</a><strong> </strong><em>at&nbsp;</em><a href="https://dev.to/n_tepluhina/apollo-state-management-in-vue-application-8k0" target="_blank">dev.to</a>

This article assumes you already know what GraphQL and Apollo client are and you're able to build Vue applications with Vue CLI## Why do we need Apollo local state management?

Imagine a Vue application fetching some data from a REST API. Where do you usually store this data? Probably, the answer would be 'in the local component state' or, if application is big enough, 'in the Vuex store with the rest of data'. This answer makes sense, because we can have the single source of truth for our application.

Now imagine an application fetching data from a GraphQL endpoint with Apollo client. By default, Apollo will store this data to Apollo cache. But what if we have some local application state, stored in Vuex? If we copy data from Apollo cache to Vuex, we're doubling our data. If we leave data from the API in Apollo and local data in Vuex, there will be two sources of truth. What would be a good way to store local data?

Previously there was a library named apollo-link-state to manage local data. But since Apollo 2.5 release, we don't need it anymore because this functionality is now a part of Apollo core. So, we can simply manage our local state without adding any new dependencies πŸŽ‰

What are we going to build

Let's try to create a simple to-do application with Vue and Apollo client.

I've started with a Vue CLI-powered to-do application with some custom styles. You can find its source code here.

Add Apollo to Vue application

First thing we need is to install Apollo client and integrate it to our Vue app. For integration, we will use vue-apollo plugin.

To install everything we need, type the following command in the terminal:

npm install --save vue-apollo graphql apollo-boost

or

yarn add vue-apollo graphql apollo-boost

Then open main.js file and add

// main.js

Vue.use(VueApollo);

This way we're adding the vue-apollo plugin to our Vue application.

Now we need to configure our Apollo client. First, let's add an import on the top of main.js file:

// main.js

import ApolloClient from 'apollo-boost';
// rest of imports

Vue.use(VueApollo);

Then, let's create a client:

// main.js

import ApolloClient from 'apollo-boost';
// rest of imports

Vue.use(VueApollo);

const apolloClient = new ApolloClient({});

Add a provider based on this newly created client and inject it to Vue application instance:

// main.js

const apolloProvider = new VueApollo({
  defaultClient: apolloClient,
});

new Vue({
  render: h => h(App),
  apolloProvider, //here goes your Apollo provider
}).$mount('#app');

Now we're ready to create an Apollo-powered store.

Initializing an Apollo cache

We're going to initialize an Apollo cache where we will store our to-do items. Apollo has an InMemoryCache constructor to do this:

// main.js

import ApolloClient from 'apollo-boost';
import { InMemoryCache } from 'apollo-cache-inmemory';

// rest of imports

const cache = new InMemoryCache();

Now we need to add it to our client:

// main.js

const apolloClient = new ApolloClient({
  cache,
});

So far our cache is empty and we're going to add some data to it. But first let's create a local schema. This step could be optional, but just like how a schema is the first step toward defining our data model on the server, writing a local schema is the first step we take on the client.

Creating a local schema

Let's think for a minute: what should our to-do item look like? It definitely needs to have some text but what else? Probably we need some property to define if it's already done or not and also an ID to distinguish one todo-item from another. So, it should be an object with three properties:

{
  id: 'uniqueId',
  text: 'some text',
  done: false
}

Now we're ready to add item type to GraphQL local schema.

Let's create a new file resolvers.js in the src folder and add the following code to it

import gql from 'graphql-tag';

export const typeDefs = gql`
  type Item {
    id: ID!
    text: String!
    done: Boolean!
  }
`;

gql here stands for the JavaScript template literal tag that parses GraphQL query strings.

Awesome! Let's import typeDefs and add them to our Apollo client:

// main.js

import ApolloClient from 'apollo-boost';
import { InMemoryCache } from 'apollo-cache-inmemory';
import { typeDefs } from './resolvers';
// rest of imports

const apolloClient = new ApolloClient({
  cache,
  typeDefs,
  resolvers: {},
});

Please note the empty resolvers object here: if we don't assign it to the Apollo client options, it won't recognize the queries to local state and will try to send a request to remote URL instead
Now we need to add some initial data to our cache. To directly write it here, we will use the writeQuery method:

// main.js

// apollo client code

cache.writeData({
  data: {
    todoItems: [
      {
        __typename: 'Item',
        id: 'dqdBHJGgjgjg',
        text: 'test',
        done: true,
      },
    ],
  },
});

// apollo provider code

We've just added an array of todoItems to our cache data and we are saying that every item has a type name of Item (specified in our local schema).

Now we're ready to query our local data from our Vue component!

Query local data

First, we need to build a GraphQL query to retrieve the data. Let's create a graphql folder, add a queries.js file to it and import graphql-tag there.

// queries.js

import gql from 'graphql-tag';

Now let's write a query:

// queries.js

import gql from 'graphql-tag';

export const todoItemsQuery = gql`
  {
    todoItems @client {
      id
      text
      done
    }
  }
`;

So, we defined the name of the query here (todoItems) and we specified that this query should not be executed against remote GraqhQL API. @clientdirective here tells Apollo client it should fetch results in the local data store.

Finally, we're ready to send the query from the Vue component. To do so, let's open our App.vue, import the query constant there:



What's going on here? We call the $apollo.mutate method (provided with vue-apollo plugin) and we pass the mutation we created earlier in queries.js and an id variable (ID is passed from the template where we're checking the item):

<ListItem
  v-for="(item, index) in todoItems"
  :key="index"
  :content="item"
  @toggleDone="checkItem(item.id)"
  @delete="deleteItem(item.id)"
/>

Now when we're clicking on the checkbox, we will send a mutation that changes our local state. We can see immediately that our todoItems array is changed with this mutation so checkbox becomes checked/unchecked.

Deleting an item

Now we need the way to delete an item. Let's start again with creating a deleteItem mutation:

// queries.js

export const deleteItemMutation = gql`
  mutation($id: ID!) {
    deleteItem(id: $id) @client
  }
`;

As you can see, it's very similar to the previous one: again, we're passing an ID as a parameter. Now let's add a resolver for it:

// resolvers.js

deleteItem: (_, { id }, { cache }) => {
  const data = cache.readQuery({ query: todoItemsQuery });
  const currentItem = data.todoItems.find(item => item.id === id);
  data.todoItems.splice(data.todoItems.indexOf(currentItem), 1);
  cache.writeQuery({ query: todoItemsQuery, data });
  return true;
},

Again, we're reading the todoItemsQuery from the cache as a first step and writing it back later (and we're simply returning true to show the request was successful). But instead of changing currentItem we're just removing it from the todoItems array.

Now let's add this mutation to the App.vue.



Very similar to checkItem, isn't it?

Adding new item

While the two previous mutations were really similar to each other, addItemwill be different. First of all, we will pass a text, not an ID, and we want to be able to see what is actually added:

// queries.js

export const addItemMutation = gql`
  mutation($text: String!) {
    addItem(text: $text) @client {
      id
      text
      done
    }
  }
`;

You can assume the resolver will be more complex as well: we need to generate a unique ID somehow. For this project we're going to use shortidlibrary:

npm install shortid

or

yarn add shortid

Now let's start building our resolver:

// resolvers.js
import shortid from 'shortid';

export const resolvers = {
  Mutation: {
    ...
    addItem: (_, { text }, { cache }) => {
      const data = cache.readQuery({ query: todoItemsQuery });
      const newItem = {
        __typename: 'Item',
        id: shortid.generate(),
        text,
        done: false,
      };
    },
  }
}

As you can see, now we're taking a text from our mutation arguments and set a newItem text property equal to it. For id we're generating a new unique ID with shortid.generate method. As for done property, we always set it to false when creating a new todo-item (because obviously it's not done yet!).

Now we need only to push this newly created item to the todoItems array, write the data back to the cache and return a newItem as a mutation result.

// resolvers.js

addItem: (_, { text }, { cache }) => {
  const data = cache.readQuery({ query: todoItemsQuery });
  const newItem = {
    __typename: 'Item',
    id: shortid.generate(),
    text,
    done: false,
  };
  data.todoItems.push(newItem);
  cache.writeQuery({ query: todoItemsQuery, data });
  return newItem;
},

We're ready to call our addItem mutation from the component! Let's import it to App.vue...



...and add it to the addItem method:

  addItem() {
    if (this.newItem) {
      this.$apollo.mutate({
        mutation: addItemMutation,
        variables: { text: this.newItem }
      });
      this.newItem = "";
    }
  },

newItem here represents a string from the input field and we're going to call a mutation only when we have some actual text to send. Also, after we've added a new item, we want to clear an input.

Yay, our application is ready! πŸŽ‰

You can find the full application source code here.

What are the differences between the various JavaScript frameworks? E.g. Vue.js, Angular.js, React.js

What are the differences? Do they each have specific use contexts?

What are the differences? Do they each have specific use contexts?

Ember.js vs Vue.js - Which is JavaScript Framework Works Better for You

Ember.js vs Vue.js - Which is JavaScript Framework Works Better for You

In this article we will discuss full details and comparison of both Ember.js and Vue.js

JavaScript was initially created to work for web applications. But today they have become the favorite of mobile app developers. Most of the developers prefer to work with frameworks based on JavaScript. It simplifies coding. You can use JavaScript with almost any framework.

The use of a particular framework will decide how easy and fast it is to create the app. So, you must choose the best one suited for the app that you are planning to build. You must make a wise choice so that you benefit in the end. Among the crowded market, two of the frameworks stand out. We will make a comparison between Ember.js and Vue.js.

Why Do You Select A Particular Framework?

Before we start comparing the two frameworks, we should understand the factors that lead to the choice of a framework. Each developer chooses a framework before he or she goes to work on an app. Let us see the reasons for the selection.

● The codes must be easy to understand and transparent.

● The framework should give the maximum power with the least amount of coding.

● The framework should provide a well laid out structure to work on.

● Does the framework support an in-built router or an external plug-in router?

● The framework should be able to transfer more data on a full page-load so that it becomes a single-page app. A single-page app is more beneficial for the application.

● In single page architectures if there is a need for users to share links to sub-screens within the interface, then the framework should have the capacity to route based on the URL.

● A tighter template option can help in enabling two-way binding.

● The framework should not conflict any third-party library.

● Testing the codes inside the framework should be easy.

● The framework should provide the HTTP client service for AJAX calls

● The documentation is essential. It should be complete and up-to-date.

● The framework should be compatible with the latest version of the browser.

● The framework has to fulfill the above conditions for easy construction of the app. You must ensure that the framework you choose meets the conditions.

Vue.js Explained

Developers are always looking at new frameworks to build their apps. The main requirements are speed and low cost. The framework should be easy to use by even new developers. You should be able to use it at low cost. Other considerations are about simple coding, proper documentation, etc.

Vue.js combines a lot of good when it comes to software language for web app development. The architecture of Vue.js is easy to put in use. The apps developed using Vue.js are easy to integrate with new apps.

Vue.js is a very lightweight framework. It makes it fast to download. It is also much faster than other frameworks. The single-file component nature of the framework is also beneficial. The size has made it very popular.

You can further decrease weight. With Vue.js you can separate the template-to-virtual DOM and compiler. You can only deploy the minified and zipped interpreter which is only 12 KB. You can compile the templates in your machine.

Another significant advantage of Vue.js is that it can integrate easily with existing applications created with JavaScript. It will make it easy for using this framework to make changes to applications already present.

Vue.js also integrates easily with other front-end libraries. You can plug in another library and make up for any deficiency in this framework. This feature makes this tool a versatile one.

Vue.js uses the method of rendering on the streaming-side server. You can render your component and get a readable stream. You can then send this to the HTTP server. It makes the server highly responsive. Your users will get the rendered content very quickly.

Vue.js is very SEO friendly. As the framework supports server-side rendering, the views are rendered directly on the server. The search engines list these.

But the most important thing for you is the ease with which you can learn Vue.js. The structure is elementary. Even new developers will find it easy to use it to build their apps. This framework helps in developing both small and large templates. It helps to save a lot of time.

You can go back and check your errors very easily. You can travel back and inspect all the states apart from testing your components. It is another important feature as far as any developer is concerned.

Vue.js also has very detailed documentation. It helps in writing your applications very quickly. You can build a web page or app with the basic knowledge of HTML or JavaScript.

● Vue.js has pure architecture. It helps in integration with other apps

● Vue.js is lightweight and fast. It can be made lighter by deploying only the interpreter

● You can separate the compiler and the template-to-virtual DOM.

● Due to smooth integration, you can use this to make changes to existing apps

● To make up for any shortfall, you can plug-in any library and makeup.

● As Vue.js uses streaming-side server rendering, your users can get quick responses.

● The server-side rendering also helps in being ranked higher by search engines.

● It has a simple structure. Easy to use for any new developer

● You can go back and check and correct your errors.

● You can check all the existing states.

● Detail documentation also helps build the web page or application very quickly.

Ember.js Decoded

Ember.js is an MVVM model framework. It is open-source software. This platform is mostly used for creating complex multi-page applications. It maintains up-to-date features without discarding any of the old features.

With this framework, you have to follow the architecture of the framework strictly. The JS framework is very tightly organized. It reduces the flexibility that other frameworks might offer.

There is a very refined and developed control system for its platforms and tools. You can integrate it with the new version with the tools provided. There is strict guidance about avoiding outdated APIs.

You can understand Ember’s APIs easily. They are also easy to work. You can make use of highly complex functionalities simply and straightforwardly.

The performance is better as similar jobs are processed together. It creates batches of similar bindings and DOM updates to improve the performance. It means that the browser needs to process them in one go. It will avoid recomputing for each task, wasting a lot of time.

You can write the codes in a simple manner and modules. You can use any of Ember’s APIs. It is possible due to the presence of Promises everywhere.

Ember comes with a well-written guide. The API is recorded in a useful manner. It is a front-end framework that is loaded. Ember has a router, pipeline, services, etc. of its own.

The basis for views, controllers, models, and framework is the Ember Object Model. All components come from the same objects. The framework is firm and steady. The reason is that all elements have similar jobs and characteristics.

Ember has made the general application, organization, and structure clear so that you don’t make any mistakes. You will have no chance to complicate the application unnecessarily. If you have to go out of the defined limits, you will have to force your way out.

The language used for templating in Embers is Handlebars. This language helps Embers to keep its logic out of view. The clean syntax of Handlebars makes it easy for you to read and understand the templates. Handlebar templates are faster to load.

Another advantage you gain from Handlebar is that you don’t have to update your template every time you add or remove data from the page. It will be done automatically by the language itself.

A community that is continually improving the framework supports Ember. They are updating the framework with the latest technology. They also make sure that backward compatibility is possible.

● Ember.js is an open-source MVVM model framework suitable for complex multiple-page applications.

● It offers both the latest and old features.

● It has a very tightly structured framework which doesn’t offer much flexibility

● A very refined control system helps you to integrate with new versions without any problem.

● There is strict guidance about avoiding outdated API versions.

● Ember’s APIs help you to use complex functionalities in a simple manner

● There is no recomputing for each task as the framework allows the browser to do similar functions together.

● Promises allow you to write modular and straightforward code using any API of Ember.js.

● Ember.js is a fully loaded, front-end framework.

● The framework is stable because all components have the same functionalities and properties.

● It has well-defined limitations which will prevent your complicating your application

● Handlebars, the language used by Ember.js allows you to read and understand templates easily. It also helps to load the templates faster.

● Handlebars will ensure to update the template every time you add or remove data.

● Ember.js has an active community that updates the framework regularly and facilitates backward compatibility.

A Comparison Between Ember.js And Vue.js

This article intends to compare the features of both frameworks. Let us see how the characteristics of these frameworks compare. It will help you to make use of the right framework for your web application.

When you need a modern engine for an old application, it is Vue.js which will help you. It combines the best properties of other frameworks. Vue.js is a developing framework. A ready-to-use library of interface elements does not exist. However, many third-party libraries can help you.

Ember.js offers you a well-organized and trustworthy framework. When the development team is big, this is the framework that suits best. It allows everyone to understand the written code and contribute to a common project. The technology will be up-to-date, and the platform will be stable.

Vue.js can help you use the syntax of different kinds. It helps in writing the codes with ease. It is also an SEO friendly framework. Ember is a fully loaded front-end framework and can help you develop the applications very fast. But it is not suitable for developing small projects.

It is not easy to say this is better than that. It will depend on what kind of project you have undertaken. Both have their pluses and minuses. The below table will help in a better comparison.

Final Thoughts

It is not easy to conclude as to which is better. It all depends on the application that you want to develop. Both frameworks are developing. Both are getting updates. Both the communities are working on the frameworks.

While Vue.js is more comfortable for writing codes, Ember is a full-stack framework allowing the development of apps very fast. It is suitable for big projects. It is too complicated to be used for smaller projects.

We hope you had a great time reading this article. If you’ve any questions or suggestions related to this blog, then feel free to ask them in the comment section. Thank You.!