How to solve the "[Vue warn]: Invalid prop: custom validator" error

How to solve the "[Vue warn]: Invalid prop: custom validator" error

In the process of using Vue to develop, we often encounter some warnings and errors information. One of the common error messages is "[Vue warn]: Invalid prop: custom validator". The reason this error message occurs is because we failed to properly validate the value passed to the component when using a custom validator function.

The following are several common causes that may cause this error and their corresponding solutions.

1. Custom validator function not defined correctly

Before you start to resolve this error, please make sure that you have defined your custom validator function correctly. A validator function is a function that receives one parameter, which is the value passed to the component. The function either returns true to indicate that the verification passed, or returns a string to indicate that the verification failed and provides the corresponding error message.

The following is a simple example:

Vue.component('my-component', {
  props: {
    value: {
      validator: function (value) {
        return ['foo', 'bar'].indexOf(value) !== -1
      }
    }
  },
  template: '<div>{{ value }}</div>'
})

The value attribute in the above code defines a custom validator function, which verifies whether the value passed to the component is "foo" or "bar". If any other value is passed, the "[Vue warn]: Invalid prop: custom validator" error will be triggered.

If you have not defined the correct custom validator functions, then you need to check your code and make sure they are defined and used correctly.

2. Incorrect syntax used

When using a custom validator function, sometimes we will cause the validator to fail to run correctly due to syntax errors, thus triggering " [Vue warn]: Invalid prop: custom validator" error.

Here are some examples of possible syntax errors:

• Forgot to use the return statement inside the validator function to return the validation results.
• Forgot to define the parameters passed to the validator function.

You can solve this problem by double-checking your code and making sure the syntax is correct.

The following is a sample code, which uses an incorrect syntax, resulting in the error message:

Vue.component('my-component', {
  props: {
    value: {
      validator: function (value) {
        ['foo', 'bar'].indexOf(value) !== -1
      }
    }
  },
  template: '<div>{{ value }}</div>'
})

The validator function in the above sample code does not use the return statement to return the verification result , resulting in the "[Vue warn]: Invalid prop: custom validator" error.

3. Unsupported data type is used

When we use a custom validator function to verify the value passed to the component, sometimes the value passed to the component is not supported. The data type triggers the "[Vue warn]: Invalid prop: custom validator" error.

The following is a sample code in which an unsupported data type is passed to the component:

Vue.component('my-component', {
  props: {
    value: {
      type: String,
      validator: function (value) {
        return ['foo', 'bar'].indexOf(value) !== -1
      }
    }
  },
  template: '<div>{{ value }}</div>'
})

// 传递了一个数字类型的值
<my-component :value="123"></my-component>

In the above sample code, a value# that accepts a string type is defined ## attribute and validating using a custom validator function, a numeric value is passed. This will trigger the "[Vue warn]: Invalid prop: custom validator" error.

To resolve this error, we need to ensure that the value passed to the component is compatible with the defined data type.

Summary

During the development process using Vue, we often encounter "[Vue warn]: Invalid prop: custom validator" error. We can easily solve this problem by properly defining a custom validator function, using the correct syntax, and ensuring that the value passed to the component is compatible with the defined data type.

Hope this article can help you better understand and solve the "[Vue warn]: Invalid prop: custom validator" error.

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