using the information from the child array within a v-if condition

Question

using the information from the child array within a v-if condition

I'm struggling to extract data from a child array and utilize it in my v-if condition.

Below are my data and code. Any assistance would be appreciated, even if it's just pointers to the right documentation.

<div  class='post' v-for="message in messages"  v-if='["Food","Featured"].includes(tag) || tag === ""'>
            
            <h2>{{message.text}}</h2>

            <div v-for="category in message.categories">
              {{category.name}}
            </div> 

</div>

Rather than

v-if='["Food","Featured"]

, I've been attempting

v-if='[category in message.categories]

Clearly, that's not correct. How can I correctly pass data from a nested array UP to the v-if statement?

The data is provided below:

[
   {
      "text":"Featured food content",
      "categories":[
         {
            "name":"Featured",
            "ID": "189"
         },
         {
            "name":"Food",
            "ID": "190"
         }
      ]
   },
   {
      "text":"Featured content",
      "categories":[
         {
            "name":"Featured",
            "ID": "189"
         }
      ]
   }      
]

Thank you for all your help. This is what I came up with until I figure out how to use computed properties properly.

<template v-for="message in messages">
    <div class='post' v-if='message.categories.map(c => c.name).includes(tag) || tag === ""'>
        
        <h2>{{message.text}}</h2>

        <div v-for="category in message.categories">
          {{category.name}}
        </div> 

    </div>
</template>

javascript vue.js

Answer 1

Answer №1

Important Note: When using v-for and v-if in Vue.js, they should not be combined directly. To make use of v-if, you can convert it into computed properties as shown below:

The variable this.data represents the nested data that has been declared. The filter() method is used to define the test condition.

computed: {
  filteredData: function () {
    return this.data.filter(item => item.categories !== '')
  }
}

You can then proceed with displaying the desired content by iterating through the filtered values:

<div v-for="element in filteredData">{{element}}</div>

Answer 2

Important Note: When using v-for and v-if in Vue.js, they should not be combined directly. To make use of v-if, you can convert it into computed properties as shown below:

The variable this.data represents the nested data that has been declared. The filter() method is used to define the test condition.

computed: {
  filteredData: function () {
    return this.data.filter(item => item.categories !== '')
  }
}

You can then proceed with displaying the desired content by iterating through the filtered values:

<div v-for="element in filteredData">{{element}}</div>

Answer 3

Answer №2

If you're looking for a solution, here's one that might meet your needs. Feel free to reach out if you need further assistance. It seems there was some uncertainty about the issue based on the code provided.

<div id="app">
  <div
    v-for="message in messages"
    v-if="messageHasCategory(message, currentCategory)"
  >
    {{message.text}}
  </div>
</div>

const app = new Vue({
  el: "#app",
  data: {
    currentCategory: 'Food',
    messages: [{
      text: 'Food message',
      categories: [{
        name: "Food"
      }]
    }, {
      text: 'Featured message',
      categories: [{
        name: "Featured"
      }]
    }]
  },
  methods: {
    messageHasCategory(message, categoryName) {
      return message.categories.find(c => {
        return c.name == categoryName;
      })
    }
  }
})

Alternatively, you can merge the v-for and v-if into a single computed property as suggested by @zerbene.

<div id="app">
  <div v-for="message in currentCategoryMessages">
    {{message.text}}
  </div>
</div>

const app = new Vue({
  el: "#app",
  data: {
    currentCategory: 'Food',
    messages: [{
      text: 'Food message',
      categories: [{
        name: "Food"
      }]
    }, {
      text: 'Featured message',
      categories: [{
        name: "Featured"
      }]
    }]
  },
  computed: {
    currentCategoryMessages() {
      return this.messages.filter(m => {
        return m.categories.map(c => c.name).includes(this.currentCategory);
      })
    }
  },
})

Check out the Codepen link for a live demo: https://codepen.io/dyllandry-the-styleful/pen/vYKEjeb

Answer 4

If you're looking for a solution, here's one that might meet your needs. Feel free to reach out if you need further assistance. It seems there was some uncertainty about the issue based on the code provided.

<div id="app">
  <div
    v-for="message in messages"
    v-if="messageHasCategory(message, currentCategory)"
  >
    {{message.text}}
  </div>
</div>

const app = new Vue({
  el: "#app",
  data: {
    currentCategory: 'Food',
    messages: [{
      text: 'Food message',
      categories: [{
        name: "Food"
      }]
    }, {
      text: 'Featured message',
      categories: [{
        name: "Featured"
      }]
    }]
  },
  methods: {
    messageHasCategory(message, categoryName) {
      return message.categories.find(c => {
        return c.name == categoryName;
      })
    }
  }
})

Alternatively, you can merge the v-for and v-if into a single computed property as suggested by @zerbene.

<div id="app">
  <div v-for="message in currentCategoryMessages">
    {{message.text}}
  </div>
</div>

const app = new Vue({
  el: "#app",
  data: {
    currentCategory: 'Food',
    messages: [{
      text: 'Food message',
      categories: [{
        name: "Food"
      }]
    }, {
      text: 'Featured message',
      categories: [{
        name: "Featured"
      }]
    }]
  },
  computed: {
    currentCategoryMessages() {
      return this.messages.filter(m => {
        return m.categories.map(c => c.name).includes(this.currentCategory);
      })
    }
  },
})

Check out the Codepen link for a live demo: https://codepen.io/dyllandry-the-styleful/pen/vYKEjeb

Answer 5

Answer №3

(This solution doesn't address the potential conflict of using both v-for and v-if simultaneously, as discussed in detail here: )

To validate category names, you can leverage the .map(...) method on your array. This will generate a new array where you can then use .includes(tag). Insert this condition within your v-if:

tag === "" || message.categories.map(c => c.name).includes(tag)

Answer 6

(This solution doesn't address the potential conflict of using both v-for and v-if simultaneously, as discussed in detail here: )

To validate category names, you can leverage the .map(...) method on your array. This will generate a new array where you can then use .includes(tag). Insert this condition within your v-if:

tag === "" || message.categories.map(c => c.name).includes(tag)

using the information from the child array within a v-if condition

Answer №1

Answer №2

Answer №3

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