CODEWITHSUNDEEP
javascriptreactjsreact-hooks
bos570
bos570

Reputation: 1523

Using nested hooks to update state

I'm trying to figure out how I can use nested hooks to update state in my parent component. I recently learned that hooks basically follow the same setState() async updating pattern but I'm struggling to find my war around that.

I have 3 custom hooks:
useValidateContent: A custom hook to validate a specific form.
useValidateRuleOne: A custom hook to validate a specific rule.
useValidateRuleTwo: A custom hook to validate another specific rule.

I want to use useValidateRuleOne and useValidateRuleTwo in useValidateContent and update the ParentComp on click. Right now it take 2 click for the messages to appear.

What is the proper way to use nested custom hooks so that state updates on first on first run. 

const { useState } = React;

const useValidateRuleOne = initState => {
    const[valid, setValid] = useState(initState)
    const[errorMsg, setErrorMsg] = useState(null)
    
    
    const validate = () => {
      // For test purposes just set to false
      setValid(false)
      setErrorMsg('There was an error validating rule one')
    }
    
    return [valid, validate, errorMsg]
    
}

const useValidateRuleTwo = initState => {
    const[valid, setValid] = useState(initState)
    const[errorMsg, setErrorMsg] = useState(null)
    
    
    const validate = () => {
      // For test purposes just set to false
      setValid(false)
      setErrorMsg('There was an error validating rule two')
    }
    
    return [valid, validate, errorMsg]
    
}

const useValidateContent = initState => {
  const [valid, setValid] = useState(initState);
  const [validOne, validateOne, errorOne ] = useValidateRuleOne(true)
  const [validTwo, validateTwo, errorTwo ] = useValidateRuleTwo(true)
  const [errorMsg, setErrorMsg] = useState("");

  const validate = () => {
    validateOne()
    validateTwo()
    
    let errorMsg = ''; 
    if (!validOne) errorMsg += errorOne;
    if (!validTwo) errorMsg += errorTwo;
    
    setErrorMsg(errorMsg)
    if (errorMsg.length > 1) setValid(false)
  }

  return [valid, validate, errorMsg];
};


function ParentComp() {
  const [contentIsValid, validate, contentError] = useValidateContent(true);

  const initValidate = () => {
    // values before running validate
    validate();

  };

  return (
    <div>
      <button onClick={initValidate}>initValidate</button>
      contentIsValid: {contentIsValid.toString()}, contentError: {contentError}
    </div>
  );
}

ReactDOM.render(<ParentComp />, document.getElementById('root')) 
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/16.6.3/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.6.3/umd/react-dom.production.min.js"></script>
<script src="https://unpkg.com/react@16/umd/react.development.js"></script>
<script src="https://unpkg.com/react-dom@16/umd/react-dom.development.js"></script>

<div id="root"></div>

Upvotes: 4

Views: 10601

Answers (2)

Jameson
Jameson

Reputation: 408

According to Hooks API, you shouldn't call a hook conditionally or inside nested functions. https://reactjs.org/docs/hooks-rules.html#only-call-hooks-at-the-top-level

One solution for your issue is to add useEffect, which will fire any time your specified dependencies change. Here's a working example: https://codesandbox.io/s/5zyljjm7o4

Upvotes: 1

Pavel Kratochvil
Pavel Kratochvil

Reputation: 481

Make pure functions from validation rules and store state only on one place. It should be cleaner and also better for testing. https://codesandbox.io/s/r4v026lxno

Upvotes: 0

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