[React + GraphQL] Use useLazyQuery to manually execute a query with Apollo React Hooks

When using useQuery from Apollo React Hooks, the request will be sent automatically after the component has been mounted. This might not be the desired behaviour as we might want to send the request in response to user action (for instance, after a button click).

In this lesson we‘re going to learn how to use useLazyQuery hook to execute a query manually in order to fetch dog pictures.

import React, { Fragment, useState } from "react";
import { gql } from "apollo-boost";
import { useLazyQuery } from "@apollo/react-hooks";

const GET_DOGGO = gql`
  query Dog($breed: String!) {
    dog(breed: $breed) {
      id
      displayImage
    }
  }
`;

const App = () => {
  const [breed, setBreed] = useState("dingo");
  const [getDog, { loading, data }] = useLazyQuery(GET_DOGGO);

  if (loading) {
    return <h2>Loading...</h2>;
  }

  return (
    <Fragment>
      {data && data.dog ? (
        <img
          alt="Cute Doggo"
          src={data.dog.displayImage}
          style={{ height: 500, width: 500 }}
        />
      ) : null}
      <input
        type="text"
        onChange={event => setBreed(event.target.value)}
        placeholder="Choose breed"
      />
      <button
        onClick={() =>
          getDog({
            variables: { breed }
          })
        }
      >
        Get dog
      </button>
    </Fragment>
  );
};

export default App;

原文地址：https://www.cnblogs.com/Answer1215/p/11431567.html