Develop Reference

Not sure how to render results of useEffect in browser

Following is the data useEffect is returning in console log:
{
"sql": {
"external": false,
"sql": [
"SELECT\n date_trunc('day', (\"line_items\".created_at::timestamptz AT TIME ZONE 'UTC')) \"line_items__created_at_day\", count(\"line_items\".id) \"line_items__count\"\n FROM\n public.line_items AS \"line_items\"\n GROUP BY 1 ORDER BY 1 ASC LIMIT 10000",
[]
],
"timeDimensionAlias": "line_items__created_at_day",
"timeDimensionField": "LineItems.createdAt",
"order": {
"LineItems.createdAt": "asc"
}
I want to be able to render the above in my react app.
const ChartRenderer = ({ vizState }) => {
let ur = encodeURIComponent(JSON.stringify(vizState.query));
let u = "http://localhost:4000/cubejs-api/v1/sql?query=" + ur;
console.log(u)
useEffect(() => {
if(u !=="http://localhost:4000/cubejs-api/v1/sql?query=undefined") {
fetch(u)
.then(response => (response.json()))
.then(data => console.log(JSON.stringify(data, null, 4)))
}},[u]);
const { query, chartType, pivotConfig } = vizState;
const component = TypeToMemoChartComponent[chartType];
const renderProps = useCubeQuery(query);
return component && renderChart(component)({ ...renderProps, pivotConfig })
};

You would have to use a state variable to persist data and update it whenever the API returns some data. In a functional component, you can use the useState hook for this purpose.
const ChartRenderer = ({ vizState }) => {
// useState takes in an initial state value, you can keep it {} or null as per your use-case.
const [response, setResponse] = useState({});
let ur = encodeURIComponent(JSON.stringify(vizState.query));
let u = "http://localhost:4000/cubejs-api/v1/sql?query=" + ur;
console.log(u)
useEffect(() => {
if(u !=="http://localhost:4000/cubejs-api/v1/sql?query=undefined") {
fetch(u)
.then(response => (response.json()))
.then(data => {
// You can modify the data here before setting it to state.
setResponse(data);
})
}},[u]);
// Use 'response' here or pass it to renderChart
const { query, chartType, pivotConfig } = vizState;
const component = TypeToMemoChartComponent[chartType];
const renderProps = useCubeQuery(query);
return component && renderChart(component)({ ...renderProps, pivotConfig })
};
You can read more about useState in the official documentation here.

How to handle an unchanging array in useEffect dependency array?

I have a component like this. What I want is for the useEffect function to run anytime myBoolean changes.
I could accomplish this by setting the dependency array to [myBoolean]. But then I get a warning that I'm violating the exhaustive-deps rule, because I reference myArray inside the function. I don't want to violate that rule, so I set the dependency array to [myBoolean, myArray].
But then I get an infinite loop. What's happening is the useEffect is triggered every time myArray changes, which is every time, because it turns out myArray comes from redux and is regenerated on every re-render. And even if the elements of the array are the same as they were before, React compares the array to its previous version using ===, and it's not the same object, so it's not equal.
So what's the right way to do this? How can I run my code only when myBoolean changes, without violating the exhaustive-deps rule?
I have seen this, but I'm still not sure what the solution in this situation is.
const MyComponent = ({ myBoolean, myArray }) => {
const [myString, setMyString] = useState('');
useEffect(() => {
if(myBoolean) {
setMyString(myArray[0]);
}
}, [myBoolean, myArray]
}

Solution 1
If you always need the 1st item, extract it from the array, and use it as the dependency:
const MyComponent = ({ myBoolean, myArray }) => {
const [myString, setMyString] = useState('');
const item = myArray[0];
useEffect(() => {
if(myBoolean) {
setMyString(item);
}
}, [myBoolean, item]);
}
Solution 2
If you don't want to react to myArray changes, set it as a ref with useRef():
const MyComponent = ({ myBoolean, myArray }) => {
const [myString, setMyString] = useState('');
const arr = useRef(myArray);
useEffect(() => { arr.current = myArray; }, [myArray]);
useEffect(() => {
if(myBoolean) {
setMyString(arr.current);
}
}, [myBoolean]);
}
Note: redux shouldn't generate a new array, every time the state is updated, unless the array or it's items actually change. If a selector generates the array, read about memoized selectors (reselect is a good library for that).

I have an idea about to save previous props. And then we will implement function compare previous props later. Compared value will be used to decide to handle function change in useEffect with no dependency.
It will take up more computation and memory. Just an idea.
Here is my example:
function usePrevious(value) {
const ref = useRef();
useEffect(() => {
ref.current = value;
});
return ref.current;
}
function arrayEquals(a, b) {
return Array.isArray(a) &&
Array.isArray(b) &&
a.length === b.length &&
a.every((val, index) => val === b[index]);
}
const MyComponent = ({ myBoolean, myArray }) => {
const [myString, setMyString] = useState('');
const previousArray = usePrevious(myArray);
const previousBoolean = usePrevious(myBoolean);
const handleEffect = () => {
console.log('child-useEffect-call-with custom compare');
if(myBoolean) {
setMyString(myArray[0]);
}
};
//handle effect in custom solve
useEffect(() => {
//check change here
const isEqual = arrayEquals(myArray, previousArray) && previousBoolean === myBoolean;
if (!isEqual)
handleEffect();
});
useEffect(() => {
console.log('child-useEffect-call with sallow compare');
if(myBoolean) {
setMyString(myArray[0]);
}
}, [myBoolean, myArray]);
return myString;
}
const Any = () => {
const [array, setArray] = useState(['1','2','3']);
console.log('parent-render');
//array is always changed
// useEffect(() => {
// setInterval(() => {
// setArray(['1','2', Math.random()]);
// }, 2000);
// }, []);
//be fine. ref is not changed.
// useEffect(() => {
// setInterval(() => {
// setArray(array);
// }, 2000);
// }, []);
//changed ref but value in array are not changed -> handle this case
useEffect(() => {
setInterval(() => {
setArray(['1','2', '3']);
}, 2000);
}, []);
return <div> <MyComponent myBoolean={true} myArray={array}/> </div>;
}

React component not re-rendering on state change due to Memoize

I'm using memoize-one on a React component that is basically a table with a rows that can be filtered.
Memoize works great for the filtering but when I want to insert a new row, it won't show up on the table until I either reload the page or use the filter.
If I check the state, the new row's data is in it, so presumably what is happening is that memoize is not allowing the component to re-render even if the state has changed.
Something interesting is that the Delete function works, I am able to delete a row by removing its data from the state and it will re-render to reflect the changes...
Here's the part of the code I consider relevant but if you would like to see more, let me know:
import React, { Component } from "react";
import memoize from "memoize-one";
import moment from "moment";
import {
Alert,
Card,
Accordion,
Button,
Table,
Spinner,
} from "react-bootstrap";
import PropTypes from "prop-types";
import { getRoleMembersDetailed } from "../libs/permissions-manager-client-v1.0";
import RoleMember from "./RoleMember";
import CreateMemberModal from "./CreateMemberModal";
class RoleContainer extends Component {
filter = memoize((roleMembers, searchValue, searchCriterion) => {
const searchBy = searchCriterion || "alias";
return roleMembers.filter((item) => {
if (item[searchBy]) {
if (searchValue === "") {
return true;
}
const value = searchValue.toLowerCase();
if (searchBy !== "timestamp") {
const target = item[searchBy].toLowerCase();
return target.includes(value);
}
// Case for timestamp
const target = moment(Number(item[searchBy]))
.format("MMM DD, YYYY")
.toLowerCase();
return target.includes(value);
}
return false;
});
});
constructor(props) {
super(props);
this.state = {
collapsed: true,
roleAttributes: [],
roleMembers: [],
isLoading: true,
};
}
componentDidMount = async () => {
const roleMembers = Object.values(await this.fetchRoleMembers());
roleMembers.forEach((e) => {
e.alias = e.alias.toLowerCase();
return null;
});
roleMembers.sort((a, b) => {
if (a.alias < b.alias) {
return -1;
}
if (a.alias > b.alias) {
return 1;
}
return 0;
});
// TODO - This logic should be replaced with an API call that describes the roleAttributes.
let roleAttributes = Object.values(roleMembers);
roleAttributes = Object.keys(roleAttributes[0]);
this.setState({
roleMembers,
roleAttributes,
isLoading: false,
});
};
fetchRoleMembers = async () => {
const { roleAttributeName } = this.props;
return getRoleMembersDetailed(roleAttributeName);
};
createRoleMember = (newRoleMembers) => {
const { roleMembers } = this.state;
newRoleMembers.forEach((e) => {
roleMembers.push(e);
});
this.setState(
() => {
roleMembers.sort((a, b) => {
if (a.alias < b.alias) {
return -1;
}
if (a.alias > b.alias) {
return 1;
}
return 0;
});
return { roleMembers };
},
() => {
console.log("sss", this.state);
}
);
};
deleteRoleMember = (alias) => {
this.setState((prevState) => {
const { roleMembers } = prevState;
return {
roleMembers: roleMembers.filter((member) => member.alias !== alias),
};
});
};
render() {
const {
role,
roleAttributeName,
searchValue,
searchCriterion,
userCanEdit,
} = this.props;
const { collapsed, isLoading, roleAttributes, roleMembers } =
this.state;
const filteredRoleMembers = this.filter(
roleMembers,
searchValue,
searchCriterion
);
return (
// continues...
I don't know if it's obvious but there are two functions called filter: this.filter that belongs to memoize and Array.prototype.filter().
I did look around and found these post that says Memoize can be overridden:
If you’ve ran into a UI bug, it is simple to just return false from myComparison to temporarily override the memoization, forcing a refresh on every re-render and returning to the default component behaviour.
But I'm not sure what they mean with "return false from component"

Here's a refactoring of your code to idiomatic React Hooks style (naturally dry-coded).
Note how filtering and sorting the role members is done using useMemo() in a way that doesn't modify state; that's because they can be always recomputed from the stateful data. So long as the useMemo()s' deps array is kept in sync (there're ESLint rules to help with this), this should work with no extra re-renders. :)
Similarly, if you use useCallback (which is a special case of useMemo), you need to keep their deps arrays in sync. If you don't use useCallback, those callbacks may cause re-renders since their identity changes per-render.
import React, { Component } from "react";
import moment from "moment";
import { getRoleMembersDetailed } from "../libs/permissions-manager-client-v1.0";
function filterRoleMembers(
roleMembers,
searchValue,
searchCriterion,
) {
const searchBy = searchCriterion || "alias";
return roleMembers.filter((item) => {
if (item[searchBy]) {
if (searchValue === "") {
return true;
}
const value = searchValue.toLowerCase();
if (searchBy !== "timestamp") {
const target = item[searchBy].toLowerCase();
return target.includes(value);
}
// Case for timestamp
const target = moment(Number(item[searchBy]))
.format("MMM DD, YYYY")
.toLowerCase();
return target.includes(value);
}
return false;
});
}
// TODO: maybe use lodash's `sortBy`?
function compareByAlias(a, b) {
if (a.alias < b.alias) {
return -1;
}
if (a.alias > b.alias) {
return 1;
}
return 0;
}
async function fetchRoleMembers(roleAttributeName) {
return getRoleMembersDetailed(roleAttributeName);
}
async function loadData(roleAttributeName) {
const roleMembers = Object.values(
await fetchRoleMembers(roleAttributeName),
);
roleMembers.forEach((e) => {
e.alias = e.alias.toLowerCase();
});
// TODO - This logic should be replaced with an API call that describes the roleAttributes.
let roleAttributes = Object.values(roleMembers);
roleAttributes = Object.keys(roleAttributes[0]);
return {
roleMembers,
roleAttributes,
};
}
const RoleContainer = ({
role,
roleAttributeName,
searchValue,
searchCriterion,
userCanEdit,
}) => {
const [collapsed, setCollapsed] = React.useState(true);
const [isLoading, setIsLoading] = React.useState(true);
const [roleAttributes, setRoleAttributes] = React.useState([]);
const [roleMembers, setRoleMembers] = React.useState([]);
React.useEffect(() => {
loadData(roleAttributeName).then(
({ roleMembers, roleAttributes }) => {
setRoleAttributes(roleAttributes);
setRoleMembers(roleMembers);
setIsLoading(false);
},
);
}, [roleAttributeName]);
const createRoleMember = React.useCallback(
(newRoleMembers) => {
const updatedRoleMembers = roleMembers.concat(newRoleMembers);
setRoleMembers(updatedRoleMembers);
},
[roleMembers],
);
const deleteRoleMember = React.useCallback(
(alias) => {
const updatedRoleMembers = roleMembers.filter(
(member) => member.alias !== alias,
);
setRoleMembers(updatedRoleMembers);
},
[roleMembers],
);
const filteredRoleMembers = React.useMemo(
() =>
filterRoleMembers(roleMembers, searchValue, searchCriterion),
[roleMembers, searchValue, searchCriterion],
);
const sortedRoleMembers = React.useMemo(
() => [].concat(filteredRoleMembers).sort(compareByAlias),
[filteredRoleMembers],
);
return <>{JSON.stringify(sortedRoleMembers)}</>;
};

How to useEffect when value in localStorage changed?

In my react app i'm saving user data filters into localStorage. I want to useEffect, when that data was changed. How to correctly trigger that effect? I tried this:
useEffect(() => {
if (rawEstateObjects.length && localStorage.activeEstateListFilter) {
const activeFilter = JSON.parse(localStorage.activeEstateListFilter)
if (activeFilter.length) {
applyFilter(activeFilter)
}
}
}, [rawEstateObjects, localStorage.activeEstateListFilter])
but localStorage.activeEstateListFilter doesn't triggers the effect..

did you set value in localStorge?
if set it then:
useEffect(() => {
function activeEstateList() {
const item = localStorage.getItem('activeEstateListFilter')
if (rawEstateObjects.length && item) {
const activeFilter = JSON.parse(localStorage.activeEstateListFilter)
if (activeFilter.length) {
applyFilter(activeFilter)
}
}
}
window.addEventListener('storage', activeEstateList)
return () => {
window.removeEventListener('storage', activeEstateList)
}
}, [])
refrence answer: https://stackoverflow.com/a/61178371/7962191

React Hooks useEffect, adding dependency triggers infinite loop

Inside of my useEffect, I have a props dependency (setIsValid). When I add this dependency to the useEffect, it lands in an infinite loop.
Parent when Calling Child Component:
const setIsValid = (bool) => {
const tmpStateCopy = Object.assign({}, state);
tmpStateCopy.isValid = bool;
setState(tmpStateCopy);
};
return <Child
setIsValid={setIsValid}
/>
In the Child Component:
const { setIsValid } = props;
const [state, setState] = useState({
transformations: [],
duplicateIndexes: []
});
const { transformations, duplicateIndexes } = state;
useEffect(() => {
const invalids = transformations.find(x => (x.value === '' || x.replaceWith === ''));
const hasDuplicates = duplicateIndexes.length > 0;
const isValid = ((invalids === undefined) && (transformations.length > 0) && !hasDuplicates);
setIsValid(isValid)
console.log('got triggered');
}, [state]);
This way the code works but I always get a warning.
What I want is, that the validation is always triggered when one of the values inside the state changes (transformations / duplicateIndexes).
By adding the setIsValid() func from the props, it runs infinitely.
The Warning looks like this:
./src/components/UI/integrationBuilder/layoutElements/transformer/modules/ifModules/ifModule.js
Line 103: React Hook useEffect has missing dependencies: 'duplicateIndexes.length', 'setIsValid', and 'transformations'. Either include them or remove the dependency array react-hooks/exhaustive-deps
My question is, how can I keep the same logic without getting this warning?

Since, when state changes you will call the effect. transformations and duplicateIndexes will already be considered for. To avoid the warning, you can move the destructure within useEffect
const { setIsValid } = props;
const [state, setState] = useState({
transformations: [],
duplicateIndexes: []
});
useEffect(() => {
const { transformations, duplicateIndexes } = state;
const invalids = transformations.find(x => (x.value === '' || x.replaceWith === ''));
const hasDuplicates = duplicateIndexes.length > 0;
const isValid = ((invalids === undefined) && (transformations.length > 0) && !hasDuplicates);
setIsValid(isValid)
console.log('got triggered');
}, [state]);
Also regarding setIsValid as a dependency to useEffect, you must not do that since a new function for it is created on every render and it will cause the useEffect to to run again and again unles you refactor your code a bit.
const setIsValid = useCallback((bool) => {
setState(prev => Object.assign({}, prev, {isValid: bool});
}, []);
and now you can set setIsValid as a dependency.