reactjstypescriptreact-contextreact-hooks

Using react context with react hooks in typescript


Code below demonstrates how I'm trying to implement react's context with react hooks, idea here is that I will be able to easily access context from any child component like this

const {authState, authActions} = useContext(AuthCtx);

To begin with I create a file that exports context and provider.

import * as React from 'react';

const { createContext, useState } = React;

const initialState = {
  email: '',
  password: ''
};

const AuthCtx = createContext(initialState);

export function AuthProvider({ children }) {
  function setEmail(email: string) {
    setState({...state, email});
  }

  function setPassword(password: string) {
    setState({...state, password}); 
  }

  const [state, setState] = useState(initialState);
  const actions = {
    setEmail,
    setPassword
  };

  return (
    <AuthCtx.Provider value={{ authState: state, authActions: actions }}>
      {children}
    </AuthCtx.Provider>
  );
}

export default AuthCtx;

This works, but I get error below in value of provider, probably because I add actions in, hence the question, is there a way for me to keep everything typed and still be able to export context and provider?

I beliebe I also can't place createContext into my main function since it will re-create it all the time?

[ts] Type '{ authState: { email: string; password: string; }; authActions: { setEmail: (email: string) => void; setPassword: (password: string) => void; }; }' is not assignable to type '{ email: string; password: string; }'. Object literal may only specify known properties, and 'authState' does not exist in type '{ email: string; password: string; }'. [2322] index.d.ts(266, 9): The expected type comes from property 'value' which is declared here on type 'IntrinsicAttributes & ProviderProps<{ email: string; password: string; }>' (property) authState: { email: string; password: string; }


Solution

  • While creating Context, you are providing an initial value to it. Provide it in the same format as you expect it to be for the Provider like:

    const initialState = {
      authState : { 
          email: '',
          password: ''
      },
      authActions = {
        setEmail: () => {},
        setPassword: () => {}
      };
    };
    
    const AuthCtx = createContext(initialState);
    

    Also, you don't even need the initialState since its only passed to Consumer, if you don't have a Provider higher up in the hierarchy for the Consumer.