database

React Firebase Hooks - Realtime Database

React Firebase Hooks provides convenience listeners for lists and values stored within the Firebase Realtime Database. The hooks wrap around the firebase.database().ref().on() method.

In addition to returning the list or value, the hooks provide an error and loading property to give a complete lifecycle for loading and listening to the Realtime Database.

All hooks can be imported from react-firebase-hooks/database, e.g.

import { useList } from 'react-firebase-hooks/database';

List of Realtime Database hooks:

• useList
• useListKeys
• useListVals
• useObject
• useObjectVal

useList

const [snapshots, loading, error] = useList(reference);

Retrieve and monitor a list value in the Firebase Realtime Database.

The useList hook takes the following parameters:

• reference: (optional) firebase.database.Reference for the data you would like to load

Returns:

• snapshots: an array of firebase.database.DataSnapshot, or undefined if no reference is supplied
• loading: a boolean to indicate if the data is still being loaded
• error: Any firebase.FirebaseError returned by Firebase when trying to load the data, or undefined if there is no error

Full Example

import { useList } from 'react-firebase-hooks/database';

const DatabaseList = () => {
  const [snapshots, loading, error] = useList(firebase.database().ref('list'));

  return (
    <div>
      <p>
        {error && <strong>Error: {error}</strong>}
        {loading && <span>List: Loading...</span>}
        {!loading && value && (
          <React.Fragment>
            <span>
              List:{' '}
              {value.map(v => (
                <React.Fragment key={v.key}>{v.val()}, </React.Fragment>
              ))}
            </span>
          </React.Fragment>
        )}
      </p>
    </div>
  );
};

useListKeys

const [keys, loading, error] = useListKeys(reference);

As useList, but this hooks extracts the firebase.database.DataSnapshot.key values, rather than the the firebase.database.DataSnapshots themselves.

The useListKeys hook takes the following parameters:

• reference: (optional) firebase.database.Reference for the data you would like to load

Returns:

• keys: an array of string, or undefined if no reference is supplied
• loading: a boolean to indicate if the data is still being loaded
• error: Any firebase.FirebaseError returned by Firebase when trying to load the data, or undefined if there is no error

useListVals

const [values, loading, error] = useListVals<T>(reference, options);

As useList, but this hook extracts a typed list of the firebase.database.DataSnapshot.val() values, rather than the the firebase.database.DataSnapshots themselves.

The useListVals hook takes the following parameters:

• reference: (optional) firebase.database.Reference for the data you would like to load
• options: (optional) Object with the following parameters:
  • keyField: (optional) string field name that should be populated with the firebase.firestore.QuerySnapshot.id property in the returned values

Returns:

• values: an array of T, or undefined if no reference is supplied
• loading: a boolean to indicate if the data is still being loaded
• error: Any firebase.FirebaseError returned by Firebase when trying to load the data, or undefined if there is no error

useObject

const [snapshot, loading, error] = useObject(reference);

Retrieve and monitor an object or primitive value in the Firebase Realtime Database.

The useObject hook takes the following parameters:

• reference: (optional) firebase.database.Reference for the data you would like to load

Returns:

• snapshot: a firebase.database.DataSnapshot, or undefined if no reference is supplied
• loading: a boolean to indicate if the data is still being loaded
• error: Any firebase.FirebaseError returned by Firebase when trying to load the data, or undefined if there is no error

Full Example

import { useObject } from 'react-firebase-hooks/database';

const DatabaseValue = () => {
  const [value, loading, error] = useObject(firebase.database().ref('value'));

  return (
    <div>
      <p>
        {error && <strong>Error: {error}</strong>}
        {loading && <span>Value: Loading...</span>}
        {value && <span>Value: {value.val()}</span>}
      </p>
    </div>
  );
};

useObjectVal

const [value, loading, error] = useObjectVal<T>(reference, options);

As useObject, but this hook returns the typed contents of firebase.database.DataSnapshot.val(), rather than the the firebase.database.DataSnapshot itself.

The useObjectVal hook takes the following parameters:

• reference: (optional) firebase.database.Reference for the data you would like to load
• options: (optional) Object with the following parameters:
  • keyField: (optional) string field name that should be populated with the firebase.database.DataSnapshot.key property in the returned value.

Returns:

• value: a T, or undefined if no reference is supplied
• loading: a boolean to indicate if the data is still being loaded
• error: Any firebase.FirebaseError returned by Firebase when trying to load the data, or undefined if there is no error