Kevin Powell - Community•3mo ago

React useRef() is being useless. Can't prevent re-fetching on form clear

I have a vehicle update form component with a 'clear form' button. The button resets the useState form object field values to nothing again, and due to this state change, React of course is re-rendering the entire component, which is fine for seeing blank form fields again, however this re-render is also causing fetch api's (my fetchInventory and fetchSteps) to also be re-run, which is unnecessary since the data from the fetch api's is already saved (from the component's first mounting/rendering). To avoid re-running these fetch calls upon re-render, I set some useRef variables - stepsFetched & dataFetched - to be false initially, but then set to 'true' after the first running of each fetch call (once I have the data), and then additionally, I am testing their truthness/falseness inside of the fetch function, prior to the call, to know whether to actually make the fetch call:

  const fetchSteps = async () => {
    if (stepsFetched.current) {
      console.log("stepsFetched is true");
      return;
    }

    try {
      const response = await axios.get(`${apiUrl}/api/steps`);

  const fetchInventory = async () => {
    if (dataFetched.current) {
      console.log("dataFetched is true");
      setLoading(false);
      return;
    }
    try {
      const response = await axios.get(`${apiUrl}/api/admin/vehicle/list`);
    };

  const fetchSteps = async () => {
    if (stepsFetched.current) {
      console.log("stepsFetched is true");
      return;
    }

    try {
      const response = await axios.get(`${apiUrl}/api/steps`);

  const fetchInventory = async () => {
    if (dataFetched.current) {
      console.log("dataFetched is true");
      setLoading(false);
      return;
    }
    try {
      const response = await axios.get(`${apiUrl}/api/admin/vehicle/list`);
    };

The useRefs however, are not maintaining their being set to 'true' after the initial mounting/rendering of the component, into the second rerender, so as to trigger these if() statements and prevent another fetch. Am I doing something else wrong here? Shouldn't they still be 'true' on a re-render? Are the 'await' or 'async' keywords here causing the problem possibly?

VehicleUpdateForm_2....

3 Replies

missymae•3mo ago

It's a dense chunk of code, and with nothing to experiment on, I'm shooting in the dark - sorry if I mislead or waste your time. I think about useMemo and useCallback in this situation. I also would have thought this is a single component problem React 19 would handle with the new compiler, which I haven't experienced. The

React.useState()

React.useState()

style is outdated, so maybe you want to review new React docs and see if upgrading would solve the problem for you.

glutonium•3mo ago

i myself is new to react but here's an abstract code on how I'd do it, which is same as what u described. I can't see thw code cause m on mobile

const isFecthedAlready = useRef(false);

useEffect(() => {
    if(isFetchedAlready) { return }

    handleFetch();
    isFetchedAlready.current = true;
}, []);

    return (
        <form>
            {/* other elemets */}
            <button
                id="close"
                onClick={() => setFormData()}
             > Clear Form </button>
        </form>
    )

const isFecthedAlready = useRef(false);

useEffect(() => {
    if(isFetchedAlready) { return }

    handleFetch();
    isFetchedAlready.current = true;
}, []);

    return (
        <form>
            {/* other elemets */}
            <button
                id="close"
                onClick={() => setFormData()}
             > Clear Form </button>
        </form>
    )

thethingisbackOP•3mo ago

thank you. I tried both useCallback and useMemo and still seeing the fetch call being re-run, but I've lightened significantly the fields being retrieved from the table, so I think I'm just going to roll with that for now. I'll have to come back and play with this more later.

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React useRef() is being useless. Can't prevent re-fetching on form clear