How to solve the problem that vue level three data cannot be obtained

Vue is a very popular JavaScript framework for building user interfaces. In Vue development, third-level data acquisition is a common problem. If you encounter the problem of not being able to obtain Vue's third-level data, don't worry, I will provide you with several solutions below.

1. Using recursive components

A recursive component means that the component calls itself in its own template. By using recursive components, you can easily handle tree-structured data.

The following is a simple example of a recursive component:

<template>
  <ul>
    <li v-for="item in data" :key="item.id">
      {{ item.label }}
      <tree-view v-if="item.children" :data="item.children"></tree-view>
    </li>
  </ul>
</template>

<script>
export default {
  name: "TreeView",
  props: {
    data: {
      type: Array,
      required: true,
    },
  },
};
</script>

In the example, the TreeView component calls itself using its own template. If item.children in the data is not null, create a new TreeView component to handle the child data. This method can easily handle unlimited levels of data.

2. Using the computed attribute

The computed attribute is a very useful feature in Vue. Use the computed attribute to create derived data based on existing data. When dealing with third-level data acquisition problems, we can use the computed attribute to handle the derivation of data.

The following is a simple example:

<template>
  <div>
    <ul>
      <li v-for="item in firstLevelData" :key="item.id">
        {{ item.label }}
        <ul>
          <li v-for="secondItem in item.children" :key="secondItem.id">
            {{ secondItem.label }}
            <ul>
              <li v-for="thirdItem in secondItem.children" :key="thirdItem.id">
                {{ thirdItem.label }}
              </li>
            </ul>
          </li>
        </ul>
      </li>
    </ul>
  </div>
</template>

<script>
export default {
  name: "Tree",
  props: {
    data: {
      type: Array,
      required: true,
    },
  },
  computed: {
    firstLevelData: function () {
      return this.data.filter((item) => item.level === 1);
    },
  },
};
</script>

In the example, we use the computed attribute firstLevelData to filter the first-level data. This makes it easy to process tertiary data and render it in the template.

3. Using Vuex

Vuex is a state management tool in Vue. By using Vuex, you can easily handle the fetching and processing of tertiary data.

The following is a simple example:

// state
state: {
  firstLevelData: [],
  secondLevelData: [],
  thirdLevelData: [],
},
// mutations
mutations: {
  SET_FIRST_LEVEL_DATA: (state, data) => {
    state.firstLevelData = data;
  },
  SET_SECOND_LEVEL_DATA: (state, data) => {
    state.secondLevelData = data;
  },
  SET_THIRD_LEVEL_DATA: (state, data) => {
    state.thirdLevelData = data;
  },
},
// actions
actions: {
  fetchData({ commit }) {
    axios.get("/api/data").then((res) => {
      commit("SET_FIRST_LEVEL_DATA", res.data.firstLevel);
      commit("SET_SECOND_LEVEL_DATA", res.data.secondLevel);
      commit("SET_THIRD_LEVEL_DATA", res.data.thirdLevel);
    });
  },
},

In the example, we use Vuex to handle the acquisition and processing of third-level data. We use mutations to set data and actions to get data. This makes it easy to manage third-level data and render it in components.

Summary

In Vue development, three-level data acquisition may be a common problem. You can easily solve this problem by using recursive components, computed properties and Vuex. You can choose the appropriate solution based on your actual situation.

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