Querying the API

React-admin provides special hooks to emit read and write queries to the dataProvider, which in turn sends requests to your API. Under the hood, it uses React Query to call the dataProvider and cache the results.

Getting The `dataProvider` Instance

React-admin stores the dataProvider object in a React context, so it’s available from anywhere in your application code. The useDataProvider hook grabs the Data Provider from that context, so you can call it directly.

As dataProvider methods are asynchronous, it’s common to call them in a React useEffect (for queries) or in an event handler (for mutations).

For instance, here is how to query the Data Provider for a User record on mount, combining the useDataProvider hook with the useState and useEffect hooks:

import { useState, useEffect } from 'react';
import { useDataProvider } from 'react-admin';
import { Loading, Error } from './MyComponents';

const UserProfile = ({ userId }) => {
    const dataProvider = useDataProvider();
    const [user, setUser] = useState();
    const [loading, setLoading] = useState(true);
    const [error, setError] = useState();
    useEffect(() => {
        dataProvider.getOne('users', { id: userId })
            .then(({ data }) => {
                setUser(data);
                setLoading(false);
            })
            .catch(error => {
                setError(error);
                setLoading(false);
            })
    }, []);

    if (loading) return <Loading />;
    if (error) return <Error />;
    if (!user) return null;

    return (
        <ul>
            <li>Name: {user.name}</li>
            <li>Email: {user.email}</li>
        </ul>
    )
};

Refer to the useDataProvider hook documentation for more information.

Tip: For standard data provider methods (like getOne() or update()), you should use the Query hooks and the Mutation hooks, both documented below, instead of calling useDataProvider. These hooks are easier to use, more robust, they handle the loading state for you, and they are typed.

Query Hooks

React-admin provides one query hook for each of the Data Provider read methods. They are useful shortcuts that make your code more readable and more robust. The query hooks execute on mount. They return an object with the following properties: { data, isPending, error }. Query hooks are:

useGetList calls dataProvider.getList()
useGetOne calls dataProvider.getOne()
useGetMany calls dataProvider.getMany()
useGetManyReference calls dataProvider.getManyReference()

Their input signature is the same as the related dataProvider method, i.e. they expect the resource name and the query parameters:

const { isPending, error, data } = useGetOne(resource, { id });
// calls dataProvider.getOne(resource, { id })

For instance, here is how to fetch one User record on mount using the useGetOne hook:

import { useGetOne } from 'react-admin';
import { Loading, Error } from './MyComponents';

const UserProfile = ({ userId }) => {
    const { isPending, error, data: user } = useGetOne('users', { id: userId });

    if (isPending) return <Loading />;
    if (error) return <Error />;
    if (!user) return null;

    return (
        <ul>
            <li>Name: {user.name}</li>
            <li>Email: {user.email}</li>
        </ul>
    )
};

Tip: If you use TypeScript, you can specify the record type for more type safety:

const { data } = useGetOne<Product>('products', { id: 123 });
//        \- type of data is Product

Query Options

Query hooks are powered by React Query’s useQuery hook. The third argument of query hooks is an options object letting you override useQuery options:

const { isPending, error, data } = useGetOne(
    'users',
    { id: userId },
    { enabled: userId !== undefined } // query options
);
// translates to
// const { isPending, error, data } = useQuery({
//     queryKey: ['users', 'getOne', { id: userId }],
//     queryFn: () => dataProvider.getOne('users', { id: userId }),
//     enabled: userId !== undefined
// });

Check the useQuery documentation for a detailed description of all options:

gcTime,
enabled,
networkMode,
initialData,
initialDataUpdatedAt,
meta,
notifyOnChangeProps,
placeholderData,
queryKey,
queryKeyHashFn,
refetchInterval,
refetchIntervalInBackground,
refetchOnMount,
refetchOnReconnect,
refetchOnWindowFocus,
retry,
retryOnMount,
retryDelay,
select,
staleTime,
structuralSharing,
throwOnError.

In addition to the useQuery options, react-admin query hooks also accept callbacks props in the options argument:

onError
onSettled
onSuccess

See the Success and Error Side Effects below for more details.

Tip: In react-admin components that use the query hooks, you can override the query options using the queryOptions prop. For instance, to log the dataProvider calls, in the <List> component, you can do the following:

import { List, Datagrid, TextField } from 'react-admin';

const PostList = () => (
    <List
        queryOptions={{ onSettled: (data, error) => console.log(data, error) }}
    >
        <Datagrid>
            <TextField source="id" />
            <TextField source="title" />
            <TextField source="body" />
        </Datagrid>
    </List>
);

Mutation Hooks

React-admin provides one mutation hook for each of the Data Provider write methods. These hooks execute the query when you call a callback. They return an array with the following items: [mutate, { data, isPending, error }]. mutate is a callback that you can call to execute the mutation.

Mutation hooks are:

useCreate calls dataProvider.create()
useUpdate calls dataProvider.update()
useUpdateMany calls dataProvider.updateMany()
useDelete calls dataProvider.delete()
useDeleteMany calls dataProvider.deleteMany()

Their input signature is the same as the related dataProvider method, e.g.:

const [update, { isPending, error, data }] = useUpdate(resource, { id, data, previousData });
// calls dataProvider.update(resource, { id, data, previousData })

For instance, here is a button that updates a comment record when clicked, using the useUpdate hook:

import * as React from 'react';
import { useUpdate, useRecordContext, Button } from 'react-admin';

const ApproveButton = () => {
    const record = useRecordContext();
    const [approve, { isPending }] = useUpdate('comments', {
        id: record.id,
        data: { isApproved: true },
        previousData: record
    });
    return <Button label="Approve" onClick={() => approve()} disabled={isPending} />;
};

Mutation Options

Mutation hooks are powered by React Query’s useMutation hook. The third argument of mutation hooks is an options object letting you override useMutation options:

const [update, { data, isPending, error }] = useUpdate(
    'comments',
    { id: record.id, data: { isApproved: true } },
    { 
        onSuccess: () => { /* ... */},
        onError: () => { /* ... */},
    }
);
// translates to
// const { mutate: update, data isPending, error } = useMutation({
//     mutationKey: ['comments', 'update', { id: record.id }],
//     mutationFn: () => dataProvider.update('comments', { id: record.id, data: { isApproved: true } }),
//     onSuccess: () => { /* ... */ }
//     onError: () => { /* ... */ }
// });

Check the useMutation documentation for a detailed description of all options:

gcTime,
meta,
mutationKey,
networkMode,
onError,
onMutate,
onSettled,
onSuccess,
retry,
retryDelay,
throwOnError.

In addition to the useMutation options, react-admin mutation hooks also accept the mutationMode option, letting you switch between pessimistic rendering, optimistic rendering and undoable modes. By default, side effect callbacks (onSuccess, onError, onSettled) are “pessimistic”, i.e. react-admin executes them after the dataProvider responds. You can switch to “optimistic” to execute them right when the dataProvider is called, without waiting for the response.

const [update, { data, isPending, error }] = useUpdate(
    'comments',
    { id: record.id, data: { isApproved: true } },
    { 
        mutationMode: 'optimistic',
        onSuccess: () => { /* ... */},
        onError: () => { /* ... */},
    }
);

See Optimistic Rendering and Undo below for more details.

Tip: In react-admin components that use the mutation hooks, you can override the mutation options using the mutationOptions prop. This is very common when using mutation hooks like useUpdate, e.g. to display a notification, or redirect to another page.

For instance, here is a button to approve the current comment that notifies the user of success or failure using the bottom notification banner:

import * as React from 'react';
import { UpdateButton, useNotify, useRedirect } from 'react-admin';

const ApproveButton = () => {
    const notify = useNotify();
    const redirect = useRedirect();
    return <UpdateButton
        label="Approve"
        data={{ isApproved: true }}
        mutationOptions={{
            onSuccess: (data) => {
                // success side effects go here
                redirect('/comments');
                notify('Comment approved');
            },
            onError: (error) => {
                // failure side effects go here 
                notify(`Comment approval error: ${error.message}`, { type: 'error' });
            },
        }}
    />;
};

`meta` Parameter

All query and mutation hooks accept a meta key in they second argument, in addition to normal parameters. For instance, for dataProvider.getOne():

useGetOne('books', { id, meta: /* ... */ });

It’s the responsibility of your Data Provider to interpret this parameter. React-admin doesn’t set this meta parameter in its queries, but you can use it in your components to pass special arguments or metadata to an API call.

A common usage is to require additional information from the API. For instance, the following code fetches a book and its author in one call:

const { isPending, error, data } = useGetOne(
    'books',
    { id, meta: { _embed: 'authors' } }
);

Success and Error Side Effects

To execute some logic after a query or a mutation is complete, use the onSuccess, onError and onSettled options. Such logic can be showing a notification, redirecting to another page, refreshing the data, etc. React-admin uses the term “side effects” for this type of logic, as it’s usually modifying another part of the UI.

Tip: React-admin provides the various hooks to handle the most common side effects:

useNotify: Return a function to display a notification.
useRedirect: Return a function to redirect the user to another page.
useRefresh: Return a function to force a rerender of the current view (equivalent to pressing the Refresh button).
useUnselect: Return a function to unselect lines in the current Datagrid based on the ids passed to it.
useUnselectAll: Return a function to unselect all lines in the current Datagrid.

`onSuccess`

The onSuccess function is called when the query returns. It receives the query data, the query variables or mutation variables and the query context.

onSuccess(data, variables, context) { /* ... */ }

This could be useful when you have different shapes for a resource in lists and single record views. In those cases, you might want to avoid react-admin to prefill the cache.

import { useGetList } from 'react-admin';
import { useQueryClient } from '@tanstack/react-query';
import { ListView } from './ListView';

const UserList = () => {
    const queryClient = useQueryClient();

    const { data, isPending, error } = useGetList(
        'users',
        { filters: {}, pagination: { page: 1, perPage: 10 }, sort: { field: 'id', order: 'DESC' } },
        {
            onSuccess: () =>
                queryClient.resetQueries(
                    { queryKey: ['users', 'getOne'] },
                )
        }
    );
    if (isPending) { return <Loading />; }
    if (error) { return <p>ERROR</p>; }
    return <ListView data={data} />;
};

`onError`

The onError function is called when the query fails. It receives the error, the query variables and the query context.

onError(error, variables, context) { /* ... */ }

This is useful to notify users about the error for instance.

import { useGetOne, useNotify, useRecordContext } from 'react-admin';

const UserProfile = () => {
    const record = useRecordContext();
    const notify = useNotify();
    const { data, isPending, error } = useGetOne(
        'users',
        { id: record.id },
        { onError: (error) => notify(error.message, { type: 'error' }) }
    );
    if (isPending) { return <Loading />; }
    if (error) { return <p>ERROR</p>; }
    return <div>User {data.username}</div>;
};

`onSettled`

The onSettled function is called after the query either succeeded or failed. It receives the query data (can be undefined if the query failed), the error (can be undefined when the query succeeded), the query variables and the query context.

onSettled(data, error, variables, context) { /* ... */ }

This can be useful e.g. to log all calls to the dataProvider:

import { useGetOne, useRecordContext } from 'react-admin';

const UserProfile = () => {
    const record = useRecordContext();
    const { data, isPending, error } = useGetOne(
        'users',
        { id: record.id },
        { onSettled: (data, error) => console.log(data, error) }
    );
    if (isPending) { return <Loading />; }
    if (error) { return <p>ERROR</p>; }
    return <div>User {data.username}</div>;
};

`useQuery` and `useMutation`

Internally, react-admin uses React Query to call the dataProvider. When fetching data from the dataProvider in your components, if you can’t use any of the query hooks and mutation hooks, you should use that library, too.

It brings several benefits to manual data fetching:

It triggers the loader in the AppBar when the query is running.
It reduces the boilerplate code since you don’t need to use useState, useEffect or useCallback.
It supports a vast array of options
It displays stale data while fetching up-to-date data, leading to a snappier UI
It cancels the queries automatically when they become out-of-date or inactive

See Why You Need React Query for more details.

React Query offers 2 main hooks to interact with the dataProvider:

useQuery: fetches the dataProvider on mount. This is for read queries.
useMutation: fetches the dataProvider when you call a callback. This is for write queries, and read queries that execute on user interaction.

Both these hooks accept a query key (identifying the query in the cache), and a query function (executing the query and returning a Promise). Internally, react-admin uses an array of arguments as the query key.

For instance, the initial code snippet of this chapter can be rewritten with useQuery as follows:

import * as React from 'react';
import { useQuery } from '@tanstack/react-query';
import { useDataProvider, Loading, Error } from 'react-admin';

const UserProfile = ({ userId }) => {
    const dataProvider = useDataProvider();
    const { data, isPending, error } = useQuery({
        queryKey: ['users', 'getOne', { id: userId }], 
        queryFn: ({ signal }) => dataProvider.getOne('users', { id: userId, signal })
    });

    if (isPending) return <Loading />;
    if (error) return <Error />;
    if (!data) return null;

    return (
        <ul>
            <li>Name: {data.data.name}</li>
            <li>Email: {data.data.email}</li>
        </ul>
    )
};

Tip: You may have noticed that we forward the signal parameter from the queryFn call to the dataProvider function call – in this case getOne. This is needed to support automatic Query Cancellation. You can learn more about this parameter in the section dedicated to the signal parameter.

To illustrate the usage of useMutation, here is an implementation of an “Approve” button for a comment:

import * as React from 'react';
import { useMutation } from '@tanstack/react-query';
import { useDataProvider, useRecordContext, Button } from 'react-admin';

const ApproveButton = () => {
    const record = useRecordContext();
    const dataProvider = useDataProvider();
    const { mutate, isPending } = useMutation({
        mutationFn: () => dataProvider.update('comments', { id: record.id, data: { isApproved: true } })
    });
    return <Button label="Approve" onClick={() => mutate()} disabled={isPending} />;
};

If you want to go beyond data provider method hooks, we recommend that you read the React Query documentation.

`isPending` vs `isLoading` vs `isFetching`

Query hooks and mutation hooks actually return more than one loading state variable. They return three: isPending, isFetching, and isLoading.

const { data, isPending, isFetching, isLoading } = useGetOne('users', { id: record.id });

Which one should you use? The short answer is: use isPending. Read on to understand why.

The source of these three variables is React Query. Here is how they define these variables:

isPending: The query has no data
isFetching: The query function was called and didn’t respond yet. This includes background refetching.
isLoading: The query is both pending and fetching

Let’s see how what these variables contain in a typical usage scenario:

The user first loads a page. isPending is true because the data was never loaded, and isFetching is also true because data is being fetched. So isLoading is also true.
The dataProvider returns the data. All three variables become false.
The user navigates away
The user comes back to the first page, which triggers a new fetch. isPending is false, because the stale data is available, and isFetching is true because data is being fetched via the dataProvider.
The dataProvider returns the data. Both isPending and isFetching become false

Components use the pending state to show a loading indicator when there is no data to show. In the example above, the loading indicator is necessary for step 2, but not in step 4, because you can display the stale data while fresh data is being loaded.

import { useGetOne, useRecordContext } from 'react-admin';

const UserProfile = () => {
    const record = useRecordContext();
    const { data, isPending, error } = useGetOne('users', { id: record.id });
    if (isPending) { return <Loading />; }
    if (error) { return <p>ERROR</p>; }
    return <div>User {data.username}</div>;
};

As a consequence, you should always use isPending to determine if you need to show a loading indicator.

Calling Custom Methods

Admin interfaces often have to query the API beyond CRUD requests. For instance, a user profile page may need to get the User object based on a user id. Or, users may want to “Approve” a comment by pressing a button, and this action should update the is_approved property and save the updated record in one click.

Your dataProvider may contain custom methods, e.g. for calling RPC endpoints on your API. useQuery and useMutation are especially useful for calling these methods.

For instance, if your dataProvider exposes a banUser() method:

const dataProvider = {
    getList: /* ... */,
    getOne: /* ... */,
    getMany: /* ... */,
    getManyReference: /* ... */,
    create: /* ... */,
    update: /* ... */,
    updateMany: /* ... */,
    delete: /* ... */,
    deleteMany: /* ... */,
    banUser: (userId) => {
        return fetch(`/api/user/${userId}/ban`, { method: 'POST' })
            .then(response => response.json());
    },
}

You can call it inside a <BanUser> button component as follows:

const BanUserButton = ({ userId }) => {
    const dataProvider = useDataProvider();
    const { mutate, isPending } = useMutation({
        mutationFn: () => dataProvider.banUser(userId)
    });
    return <Button label="Ban" onClick={() => mutate()} disabled={isPending} />;
};

Synchronizing Dependent Queries

All Data Provider hooks support an enabled option. This is useful if you need to have a query executed only when a condition is met.

For example, the following code only fetches the categories if at least one post is already loaded:

// fetch posts
const { data: posts, isPending } = useGetList(
    'posts',
    { pagination: { page: 1, perPage: 20 }, sort: { field: 'name', order: 'ASC' } },
);

// then fetch categories for these posts
const { data: categories, isPending: isPendingCategories } = useGetMany(
    'categories',
    { ids: posts.map(post => posts.category_id) },
    // run only if the first query returns non-empty result
    { enabled: !isPending && posts.length > 0 }
);

Optimistic Rendering and Undo

In the following example, after clicking on the “Approve” button, a loading spinner appears while the data provider is fetched. Then, users are redirected to the comments list.

import * as React from 'react';
import { useUpdate, useNotify, useRedirect, useRecordContext, Button } from 'react-admin';

const ApproveButton = () => {
    const record = useRecordContext();
    const notify = useNotify();
    const redirect = useRedirect();
    const [approve, { isPending }] = useUpdate(
        'comments',
        { id: record.id, data: { isApproved: true } },
        {
            onSuccess: (data) => {
                redirect('/comments');
                notify('Comment approved');
            },
            onError: (error) => {
                notify(`Comment approval error: ${error.message}`, { type: 'error' });
            },
        }
    );
    
    return <Button label="Approve" onClick={() => approve()} disabled={isPending} />;
};

But in most cases, the server returns a successful response, so the user waits for this response for nothing.

This is called pessimistic rendering, as all users are forced to wait because of the (usually rare) possibility of server failure.

An alternative mode for mutations is optimistic rendering. The idea is to handle the calls to the dataProvider on the client side first (i.e. updating entities in the react-query cache), and re-render the screen immediately. The user sees the effect of their action with no delay. Then, react-admin applies the success side effects, and only after that, it triggers the call to the data provider. If the fetch ends with success, react-admin does nothing more than a refresh to grab the latest data from the server. In most cases, the user sees no difference (the data in the react-query cache and the data from the dataProvider are the same). If the fetch fails, react-admin shows an error notification and reverts the mutation.

A third mutation mode is called undoable. It’s like optimistic rendering, but with an added feature: after applying the changes and the side effects locally, react-admin waits for a few seconds before triggering the call to the dataProvider. During this delay, the end-user sees an “undo” button that, when clicked, cancels the call to the dataProvider and refreshes the screen.

Here is a quick recap of the three mutation modes:

	pessimistic	optimistic	undoable
dataProvider call	immediate	immediate	delayed
local changes	when dataProvider returns	immediate	immediate
side effects	when dataProvider returns	immediate	immediate
cancellable	no	no	yes

By default, react-admin uses the undoable mode for the Edit view. As for the data provider method hooks, they default to the pessimistic mode.

Tip: For the Create view, react-admin needs to wait for the response to know the id of the resource to redirect to, so the mutation mode is pessimistic.

You can benefit from optimistic and undoable modes when you call the useUpdate hook, too. You just need to pass a mutationMode option:

import * as React from 'react';
import { useUpdate, useNotify, useRedirect, useRecordContext, Button } from 'react-admin';

const ApproveButton = () => {
    const record = useRecordContext();
    const notify = useNotify();
    const redirect = useRedirect();
    const [approve, { isPending }] = useUpdate(
        'comments',
        { id: record.id, data: { isApproved: true } }
        {
+           mutationMode: 'undoable',
-           onSuccess: (data) => {
+           onSuccess: () => {
                redirect('/comments');
-               notify('Comment approved');
+               notify('Comment approved', { undoable: true });
            },
            onError: (error) => notify(`Error: ${error.message}`, { type: 'error' }),
        }
    );
    return <Button label="Approve" onClick={() => approve()} disabled={isPending} />;
};

As you can see in this example, you need to tweak the notification for undoable calls: passing undo: true displays the ‘Undo’ button in the notification. Also, as side effects are executed immediately, they can’t rely on the response being passed to onSuccess.

The following hooks accept a mutationMode option:

Querying The API With `fetch`

Data Provider method hooks are “the react-admin way” to query the API. But nothing prevents you from using fetch if you want. For instance, when you don’t want to add some routing logic to the data provider for an RPC method on your API, that makes perfect sense.

There is no special react-admin sauce in that case. Here is an example implementation of calling fetch in a component:

// in src/comments/ApproveButton.js
import * as React from 'react';
import { useState } from 'react';
import { useNotify, useRedirect, useRecordContext, Button } from 'react-admin';

const ApproveButton = () => {
    const record = useRecordContext();
    const redirect = useRedirect();
    const notify = useNotify();
    const [loading, setLoading] = useState(false);
    const handleClick = () => {
        setLoading(true);
        const updatedRecord = { ...record, is_approved: true };
        fetch(`/comments/${record.id}`, { method: 'PUT', body: updatedRecord })
            .then(() => {
                notify('Comment approved');
                redirect('/comments');
            })
            .catch((e) => {
                notify('Error: comment not approved', { type: 'error' })
            })
            .finally(() => {
                setLoading(false);
            });
    };
    return <Button label="Approve" onClick={handleClick} disabled={loading} />;
};

export default ApproveButton;

Tip: APIs often require a bit of HTTP plumbing to deal with authentication, query parameters, encoding, headers, etc. It turns out you probably already have a function that maps from a REST request to an HTTP request: your Data Provider. So it’s often better to use useDataProvider instead of fetch.

Querying the API

Getting The dataProvider Instance

Query Hooks

Query Options

Mutation Hooks

Mutation Options

meta Parameter

Success and Error Side Effects

onSuccess

onError

onSettled

useQuery and useMutation

isPending vs isLoading vs isFetching