Utilize the method of the existing Vue component as the default value for a prop

Question

Utilize the method of the existing Vue component as the default value for a prop

Passing a function as a property to a Vue component can be done by using the @click directive. However, if you want to maintain the default behavior of the component, which relies on data from its state (such as props, data, or other methods), you may need to use a default function like method.

Is there a way to achieve this?

Here is an example with the expected behavior:

Button works fine should trigger an alert saying You are welcome!
Button nope should also trigger an alert saying You are welcome as well!, but not perform any additional action.

javascript vue.js vuejs2 vue-component

Answer 1

Answer №1

While this solution technically functions, it's a real mess:

action: {
  required: false,
  default () { 
    return () => this.innerMethod();
  },
},

I had to eliminate the type: Function declaration. Normally, when default is set as a function, it will be executed to provide the default value. However, if the prop includes type: Function, then the function itself becomes the default value. This caused problems because we lose the binding of this.

The workaround here is using an internal arrow function to access the methods that are otherwise unavailable when the default function is called.

If feasible, I recommend abandoning the use of a default and instead applying the 'default' only when it needs to be triggered. Instead of directly calling action in the click handler, opt for invoking a method named invokeAction resembling something like this:

invokeAction () {
  if (this.action) {
    this.action();
  } else {
    this.innerMethod();
  }
}

Answer 2

While this solution technically functions, it's a real mess:

action: {
  required: false,
  default () { 
    return () => this.innerMethod();
  },
},

I had to eliminate the type: Function declaration. Normally, when default is set as a function, it will be executed to provide the default value. However, if the prop includes type: Function, then the function itself becomes the default value. This caused problems because we lose the binding of this.

The workaround here is using an internal arrow function to access the methods that are otherwise unavailable when the default function is called.

If feasible, I recommend abandoning the use of a default and instead applying the 'default' only when it needs to be triggered. Instead of directly calling action in the click handler, opt for invoking a method named invokeAction resembling something like this:

invokeAction () {
  if (this.action) {
    this.action();
  } else {
    this.innerMethod();
  }
}

Answer 3

Answer №2

According to the documentation for Vue.js:

"Before a component instance is created, props are validated which means that instance properties such as data and computed will not be accessible inside default or validator functions."

(https://v2.vuejs.org/v2/guide/components-props.html)

This situation highlights how the reference to innerMethod may not be available when working with components.

Solution: If having this functionality is essential, you can utilize a later lifecycle hook (such as created or mounted) to check if the type of action is a function. If it is not a function (indicating it was not passed via prop), you can manually assign the innerMethod.

Answer 4

According to the documentation for Vue.js:

"Before a component instance is created, props are validated which means that instance properties such as data and computed will not be accessible inside default or validator functions."

(https://v2.vuejs.org/v2/guide/components-props.html)

This situation highlights how the reference to innerMethod may not be available when working with components.

Solution: If having this functionality is essential, you can utilize a later lifecycle hook (such as created or mounted) to check if the type of action is a function. If it is not a function (indicating it was not passed via prop), you can manually assign the innerMethod.

Utilize the method of the existing Vue component as the default value for a prop

Answer №1

Answer №2

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