How to fix "React Hook useEffect has a missing dependency. Either include it or remove the dependency array" problem?

Question

I want to use useEffect, but when I add getUpperGroup method, I get warning:

React Hook useEffect has a missing dependency: 'getUpperGroups'. Either include it or remove the dependency array"

My code is:

useEffect(() => {
  getUpperGroups();
  setContentData(contentGroupData);
}, [contentGroupData]);


const [contentData, setContentData] = useState<Fundation[]>([] as Fundation[]);
const [upperGroups, setUpperGroups] = useState({});

const getUpperGroups = () => {

   let newUpperGroups = upperGroups;

   contentGroupData.forEach(content=>{
     newUpperGroups = {...newUpperGroups, [content.id]: content.title};
   })

   setUpperGroups(newUpperGroups);
}

Answer 1

You have two mistakes.

1- You defined getUpperGroups after useEffect, so you can't add it to the list of useEffect dependencies.

2- if you add getUpperGroups to list of useEffect dependencies, useEffect will run on every re-render and you give a loop of re-render error.

So there is two solutions.

1- Add getUpperGroups into useEffect

const [contentData, setContentData] = useState<Fundation[]>([] as Fundation[]);
const [upperGroups, setUpperGroups] = useState({});


useEffect(() => {
  
  const getUpperGroups = () => {

   let newUpperGroups = upperGroups;

   contentGroupData.forEach(content=>{
     newUpperGroups = {...newUpperGroups, [content.id]: content.title};
   })

   setUpperGroups(newUpperGroups);
  }

  getUpperGroups();
}, [contentGroupData]);

2- Disable eslint

useEffect(() => {
  getUpperGroups();
  setContentData(contentGroupData);

  // eslint-disable-line react-hooks/exhaustive-deps
}, [contentGroupData]);


const [contentData, setContentData] = useState<Fundation[]>([] as Fundation[]);
const [upperGroups, setUpperGroups] = useState({});

const getUpperGroups = () => {

   let newUpperGroups = upperGroups;

   contentGroupData.forEach(content=>{
     newUpperGroups = {...newUpperGroups, [content.id]: content.title};
   })

   setUpperGroups(newUpperGroups);
}

Answer 2

You can either:

1. Suppress that rule for the entire project: Go to .eslintrc file and change 'react-hooks/exhaustive-deps': 'error' to 'react-hooks/exhaustive-deps': 'warn' or 'react-hooks/exhaustive-deps': 'off'

2. Supress the rule only in this instance:

useEffect(() => {
    getUpperGroups();
    setContentData(contentGroupData);
}, [contentGroupData]);


const [contentData, setContentData] = useState<Fundation[]>([] as Fundation[]);
const [upperGroups, setUpperGroups] = useState({});

const getUpperGroups = () => {

    let newUpperGroups = upperGroups;

    contentGroupData.forEach(content=>{
        newUpperGroups = {...newUpperGroups, [content.id]: content.title};
    })

    setUpperGroups(newUpperGroups);
} // eslint-disable-line react-hooks/exhaustive-deps

Answer 3

This one worked for me.

Just add this comment at the last line of useEffect:

//eslint-disable-next-line

useEffect(() => {
  getUpperGroups();
  setContentData(contentGroupData);
  //eslint-disable-next-line
}, [contentGroupData]);