Pinia: Is it better to invoke '{myStore}' or 'return myStore' within the return statement?

Question

Pinia: Is it better to invoke '{myStore}' or 'return myStore' within the return statement?

I'm currently working on integrating a Pinia store into a component of my Vue app and I'm puzzled by the need to return the store in { } instead of just returning it as is. Can someone clarify the distinction between return {foo} and return foo for me?

import { usePiniaStore } from "../stores/mainStore";

export default {

  setup() {
    const piniaStore = usePiniaStore();

    return { piniaStore }; //  why isn't it 'return piniaStore' ?
  },
};

javascript vue.js vue-composition-api pinia

Answer 1

Answer №1

To clarify, the issue at hand is not specific to Pinia but rather pertains to what Vue anticipates as a return value from the setup() function. Vue requires an object to be returned; any deviation will result in an error being thrown.

// The following code will trigger an error message stating "setup() should return an object. Received: number"
<script>
  import { defineComponent } from 'vue'
  
  export default defineComponent({
    setup() {
      let myVariable = 10
      
      return myVariable
    }
  })
</script>

This requirement exists because Vue needs to iterate through the properties of the returned object (ensuring it understands both the values and their respective names) and subsequently create matching properties on the component instance for accessibility within templates. This step is crucial.

The sample code you provided:

return { piniaStore }

is essentially equivalent to:


// Generating a new JavaScript object 
const returnObject = {
  // First part denotes the property name
  // Second part refers to the property value (derived from an existing variable)
  piniaStore: piniaStore
}

return returnObject

...and this syntax satisfies Vue's standards.

Remember that only properties of the returned object can be accessed within the template

// Although possible, only inner properties of the "myObject" will be accessible in the template
<script>
  import { defineComponent } from 'vue'
  
  export default defineComponent({
    setup() {
      let myObject = {
        variableA: 10,
        variableB: "some string"
      }
      
      return myObject
    }
  })
</script>

Utilizing

<div v-if="variableA">

will function correctly. However, employing

<div v-if="myObject">

will not yield desired results.

It is worth noting that Pinia stores are essentially objects, hence returning them directly from the setup (without encapsulating them within another object) is likely permissible and operational. Nevertheless, the underlying principles remain unchanged – your template exclusively interacts with properties (state or getters) and functions (actions) defined within the piniaStore store.

Answer 2

To clarify, the issue at hand is not specific to Pinia but rather pertains to what Vue anticipates as a return value from the setup() function. Vue requires an object to be returned; any deviation will result in an error being thrown.

// The following code will trigger an error message stating "setup() should return an object. Received: number"
<script>
  import { defineComponent } from 'vue'
  
  export default defineComponent({
    setup() {
      let myVariable = 10
      
      return myVariable
    }
  })
</script>

This requirement exists because Vue needs to iterate through the properties of the returned object (ensuring it understands both the values and their respective names) and subsequently create matching properties on the component instance for accessibility within templates. This step is crucial.

The sample code you provided:

return { piniaStore }

is essentially equivalent to:


// Generating a new JavaScript object 
const returnObject = {
  // First part denotes the property name
  // Second part refers to the property value (derived from an existing variable)
  piniaStore: piniaStore
}

return returnObject

...and this syntax satisfies Vue's standards.

Remember that only properties of the returned object can be accessed within the template

// Although possible, only inner properties of the "myObject" will be accessible in the template
<script>
  import { defineComponent } from 'vue'
  
  export default defineComponent({
    setup() {
      let myObject = {
        variableA: 10,
        variableB: "some string"
      }
      
      return myObject
    }
  })
</script>

Utilizing

<div v-if="variableA">

will function correctly. However, employing

<div v-if="myObject">

will not yield desired results.

It is worth noting that Pinia stores are essentially objects, hence returning them directly from the setup (without encapsulating them within another object) is likely permissible and operational. Nevertheless, the underlying principles remain unchanged – your template exclusively interacts with properties (state or getters) and functions (actions) defined within the piniaStore store.

Answer 3

Answer №2

Understanding Object Destructuring is essential in JavaScript. When a module returns multiple objects like {foo, goo, loo} and you only need to select foo, you can simply use return {foo}. However, if the module returns just one object, such as foo, then you can directly use return foo. Click here for more information on JavaScript Object Destructuring.

Answer 4

Understanding Object Destructuring is essential in JavaScript. When a module returns multiple objects like {foo, goo, loo} and you only need to select foo, you can simply use return {foo}. However, if the module returns just one object, such as foo, then you can directly use return foo. Click here for more information on JavaScript Object Destructuring.

Pinia: Is it better to invoke '{myStore}' or 'return myStore' within the return statement?

Answer №1

Answer №2

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