How to implement distributed database query in React Query?

How to implement distributed database query in React Query?

As applications grow in complexity, data management becomes increasingly difficult. Distributed databases become a way to solve this problem. React Query is a powerful data management library that helps us handle data query and caching efficiently.

This article will introduce how to use React Query to implement distributed database queries and provide specific code examples.

First, we need to install the React Query library:

npm install react-query

Next, we can set the React Query Provider in the root component of the application:

import { QueryClient, QueryClientProvider } from 'react-query';

const queryClient = new QueryClient();

function App() {
  return (
    <QueryClientProvider client={queryClient}>
      {/* 应用组件 */}
    </QueryClientProvider>
  );
}

When using React Query Before performing data query, we need to define an API function for obtaining data. Suppose we have an API function named getUsers to get the user list:

async function getUsers() {
  const response = await fetch('/api/users');
  const data = await response.json();
  return data;
}

Next, we can use React Query’s useQuery hook to perform data query :

import { useQuery } from 'react-query';

function UserList() {
  const { data, isLoading, error } = useQuery('users', getUsers);

  if (isLoading) {
    return <div>Loading...</div>;
  }

  if (error) {
    return <div>Error: {error.message}</div>;
  }

  return (
    <ul>
      {data.map(user => (
        <li key={user.id}>{user.name}</li>
      ))}
    </ul>
  );
}

In the above example, the useQuery hook uses a unique string users as the keyword of the query and passes in the previously defined getUsersFunction. React Query automatically caches data and updates it when needed.

If we need to sort or filter the query results, we can use the query key parameter of React Query. For example, if we need to sort based on username, we can set the query key to users?sortBy=name:

function UserList() {
  const { data, isLoading, error } = useQuery('users?sortBy=name', getUsers);
  // ...
}

Then, we can use React Query’s useMutationHook to perform data change operations. Suppose we have an API function named updateUser for updating user information:

async function updateUser(userId, userData) {
  const response = await fetch(`/api/users/${userId}`, {
    method: 'PUT',
    body: JSON.stringify(userData)
  });
  const data = await response.json();
  return data;
}

function UserDetail({ userId }) {
  const { data, isLoading, error } = useQuery(['user', userId], () => getUsers(userId));
  const mutation = useMutation(updatedData => updateUser(userId, updatedData));

  const handleUpdate = async () => {
    const updatedData = { name: 'New Name' };
    await mutation.mutateAsync(updatedData);
  };

  if (isLoading) {
    return <div>Loading...</div>;
  }

  if (error) {
    return <div>Error: {error.message}</div>;
  }

  return (
    <div>
      <p>Name: {data.name}</p>
      <button onClick={handleUpdate}>Update Name</button>
    </div>
  );
}

In the above example, we used ['user', userId] as query key and use getUsers(userId) to get data for a specific user. We then use the useMutation hook to create an object named mutation that contains a mutateAsync method for asynchronously updating user data.

Finally, we display the user's name in the component and trigger the data update operation by clicking the button.

Through the above examples, we can see that React Query provides a concise and flexible way to handle distributed database queries. Whether it is simple data acquisition, sorting, filtering, or data update operations, React Query can exert powerful functions.

Of course, the above examples are only the basic usage of React Query, and you can further customize and expand according to specific needs. I hope this article can help you use React Query to implement distributed database queries in React!

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