React - Axios 调用发出太多请求

Question

Im learning React & Redux by making a game project. I want to fetch data (attributes) by API, but it cause too many requests. Guess it can be realted to placing axios call directly in functional react component, but i have no idea how to fix it.

function Attributes({ attributes, dispatch }) {
  axios.get(`/api/heroes/1/get-attributes`).then(res => {
    dispatch(AttribAction.set(objectToArray(res.data)));
  });

  return (
    <div className="content">
      {attributes.map((attrib, index) => (
        <div
          key={index}
          className={attrib.id == null ? "attrib-block empty" : "attrib-block"}
        >
          <p>
            <strong>{attrib.name}</strong>: {attrib.value}
          </p>
          <div>
            <button
              className="attrib-button"
              onClick={() => dispatch(AttribAction.increment(attrib.id))}
            >
              +
            </button>
            <button
              className="attrib-button"
              onClick={() => dispatch(AttribAction.decrement(attrib.id))}
            >
              -
            </button>
          </div>
        </div>
      ))}
    </div>
  );
}

Answer 1

Put the code in a useEffect hook, and then pass in an array as the second parameter to specify what variables should cause it to repeat the effect if they change. An empty array says never to repeat it.

import React, { useEffect } from 'react';

function Attributes({ attributes, dispatch }) {
  useEffect({
   axios.get(`/api/heroes/1/get-attributes`)
     .then(res => {
       dispatch(AttribAction.set(objectToArray(res.data)));
     });
  }, []);

  // ... etc
}

Answer 2

You can use a useEffect hook to run the data fetching.

Passing an empty array as the dependencies means the effect will run only once.

import React, { useEffect } from 'react';

function Attributes({ attributes, dispatch }){

    useEffect(() => {
        axios.get(`/api/heroes/1/get-attributes`)
            .then(res => {
               dispatch(AttribAction.set(objectToArray(res.data)));
            });
    }, [])

    return(
        <div className="content">
            {attributes.map((attrib, index) =>
                <div key={index} className={attrib.id == null ? "attrib-block empty" : "attrib-block"}>
                    <p><strong>{attrib.name}</strong>: {attrib.value}</p>
                    <div>
                        <button className="attrib-button" onClick={() => dispatch(AttribAction.increment(attrib.id))}>+</button>
                        <button className="attrib-button" onClick={() => dispatch(AttribAction.decrement(attrib.id))}>-</button>
                    </div>
                </div>
            )}
        </div>
    );
}