How can I declare a PropType corresponding to a nullable number?

Question

I\'m looking for a PropType that means

\"this is required, and it will either be a number or be null\"

In other words,

Answer 1

Currently prop-types library don't allow this. The way i get around this is using a custom validation function

MyComponent.propTypes = {
  nullableArray: function(props, propName, componentName) {
    const { propName: data } = props;

    if (data === undefined) {
      return new Error(`Undefined ${propName} is not allowed`);
    }

    if (data !== null) {
      return; //this is allow when data is loading
    }

    if (!_.isArray(data)) {
      return new Error(`${propName} must be an array`);
    }
  }
};

You can make another step further to create a high order function to generate the validation function. this should get you started

generateRequiredOrNullValidationFunction = expectedType => {
  if (expectedType !== "array") {
    return Error(`Unexpected ${expectedType}`);
  }

  return function(props, propName, componentName) {
    const { [propName]: data } = props;

    if (data === undefined) {
      return new Error(`Undefined ${propName} is not allowed`);
    }

    if (data !== null) {
      return; //this is allow when data is loading
    }

    if (expectedType === "array" && !_.isArray(data)) {
      return new Error(`${propName} must be an array`);
    }
  };
};

In this snippet, expectedType is a enumeration such as bool , array, number ...