How to use Vue to implement data filtering and retrieval functions?

Vue is a popular JavaScript framework often used to build modern web applications. The Vue data binding system makes front-end development simpler and more intuitive. Vue also provides some useful tools for processing data, such as filtering. In this article, we will introduce how to use Vue to implement data filtering and retrieval functions.

1. Use computed properties for data filtering

Vue computed properties are responsive and can update data in real time according to changes in dependent data. This allows us to write data filters very conveniently. Computed properties can return a new array that can be used to display filtered data in our application.

In the following example, we implement the search function through an input box. We bind this input box to the data model of a Vue component instance. We then use computed properties to filter the list data to only display items that contain the search keyword.

HTML：

<div id="app">
  <input v-model="search" type="text" placeholder="Search...">
  <ul>
    <li v-for="item in filteredItems">{{ item }}</li>
  </ul>
</div>

JavaScript：

new Vue({
  el: '#app',
  data: {
    search: '',
    items: [
      'Apple',
      'Banana',
      'Orange',
      'Mango',
      'Pear'
    ]
  },
  computed: {
    filteredItems: function () {
      var search = this.search.toLowerCase();
      return this.items.filter(function (item) {
        return item.toLowerCase().indexOf(search) !== -1;
      })
    }
  }
})

We bind the input box to the search attribute through the v-model directive. We then use the v-for directive to render the filtered data into the template.

In the calculated properties of the Vue instance, we first convert the search keyword to lowercase, and then use the filter() method to filter out items that match the search keyword.

2. Combine routing and calculated properties for data filtering and retrieval

If we use Vue Router to manage routing, we can use the router's query parameters to implement more advanced search functions. This way users can see their search results in the URL and can share search results via URL query parameters.

HTML:

First, we need to change the binding of our input box so that we pass the search value as a query parameter. We use the $route object in the router to get the search parameters. Then, we modify the computed property to use the route parameters instead of the component instance’s data model.

<div id="app">
  <input v-model="search" type="text" placeholder="Search...">
  <ul>
    <li v-for="item in filteredItems">{{ item }}</li>
  </ul>
</div>

JavaScript:

const router = new VueRouter({
  routes: [{
    path: '/',
    component: App,
    name: 'home'
  }]
});

const App = {
  data: function() {
    return {
      items: [
        'Apple',
        'Banana',
        'Orange',
        'Mango',
        'Pear'
      ],
      search: ''
    };
  },
  computed: {
    filteredItems: function() {
      var search = this.$route.query.search.toLowerCase();
      return this.items.filter(function(item) {
        return item.toLowerCase().indexOf(search) !== -1;
      });
    }
  }
};

new Vue({
  router,
  el: '#app',
  template: '<router-view></router-view>'
});

We pass the router to the Vue instance and then replace the router-view directive with our component. In the component, we can use $route.query.search to get the query parameters. We then use computed properties to filter the list based on the search parameters.

In this example, as long as the user enters a new search keyword in the input box, we will update the query parameters in the URL and update the list based on the new parameters.

Summary:

In this article, we introduced the use of computed properties and routers in Vue to implement data filtering and retrieval functions. This way we allow users to view their search results in a URL and easily share the results elsewhere. We have also seen that Vue's data binding and calculated property system greatly simplifies the difficulty of implementing search and filtering functions on the front end.

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