React: checker is not a function

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.

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. ;)

Change

React.PropTypes.oneOfType(React.PropTypes.number, React.PropTypes.object)

to

React.PropTypes.oneOfType([React.PropTypes.number, React.PropTypes.object])

(the argument should be an array)

In my case, I was validating props wrong. I forgot to wrap the profile object into PropTypes shape method.

Mistake

Component.propTypes = {
  viewProfile: PropTypes.shape({
    profile: {     // it is a normal object without a PropTypes shape method
      firstName: PropTypes.string,
      lastName: PropTypes.string,
      profileImage: PropTypes.string,
    },
  }).isRequired,
};

Solution

Component.propTypes = {
  viewProfile: PropTypes.shape({
    profile: PropTypes.shape({
      firstName: PropTypes.string,
      lastName: PropTypes.string,
      profileImage: PropTypes.string,
    }),
  }).isRequired,
};