React: checker is not a function

Question

I\'m getting this weird warning message in the console for my React app.

Warning: Failed propType: checker is not a function Check the render method of <

Answer 1

In my case I got this when I used the shape function with a complex object. The solution was to go from:

outerObject: shape({
  firstInnerObject: {
    a: string,
    b: string,
  },
  secondInnerObject: {
    a: string,
    b: number,
  },
}),

To:

outerObject: shape({
  firstInnerObejct: shape({
    a: string,
    b: string,
  }),
  secondInnerObject: shape({
    a: string,
    b: number,
  }),
}),

Very trivial, I know, yet this might be the solution for someone equally inexperienced as I am. ;)

Answer 2

FWIW, I was getting Failed PropType: typeChecker is not a function. I noticed that in my PropTypes.arrayOf() properties, I was passing in an object of PropTypes e.g. PropTypes.arrayOf({})instead of passing in PropTypes.shape() e.g. PropTypes.arrayOf(PropTypes.shape({})

Making this change eliminated the error message.

Answer 3

In my case I'd simply accidentally removed a type:

grValue: PropTypes, // instead of PropTypes.string

Answer 4

I too got this error on putting proptypes in wrong format:

static propTypes = {
  workHard: PropTypes.func.isRequired,
  winBig: PropTypes.shape({
    prize: { // issue
      PENDING: PropTypes.bool,
    },
  }),
};

Turns out, prop types are expected to be either of type PropTypes.shape or PropTypes.objectOf when it comes to declaring object props

So, error was fixed upon changing code to this:

static propTypes = {
  workHard: PropTypes.func.isRequired,
  winBig: PropTypes.shape({
    prize: PropTypes.shape({
      SUCCESS: PropTypes.bool,
    }),
  }),
};

Answer 5

A pull request has been merged to the React repo that provides a better feedback for the developer whenever a mistake like this happens again.

Now, the validation message will look like the following:

Invalid argument supplied to oneOf, expected an instance of array.

https://github.com/facebook/react/pull/3963

This should be part of React 0.14.

Answer 6

My version of Warning: Failed propType: checker is not a function came from forgetting to use PropTypes.shape for an object.

Changing:

someProps: {
    prop: React.PropTypes.string,
    anotherProp: React.PropTypes.number,
}

to this fixed the problem:

someProps: React.PropTypes.shape({
    prop: React.PropTypes.string,
    anotherProp: React.PropTypes.number,
})