[database] Add useListKeys hook

Author: chrisbianca

README.md

@@ -199,20 +199,36 @@ const DatabaseList = () => {
 };
 ```
 
-#### `useListVal<T>(ref, keyField)`
+#### `useListKeys<T>(ref)`
 
-As above, but this hook returns a typed list of the `DataSnapshot.val()` values, rather than the the
+As above, but this hook returns a list of the `DataSnapshot.key` values, rather than the the
+`DataSnapshot`s themselves.
+
+Parameters:
+- `ref`: `firebase.database.Reference`
+
+Returns:
+`ListKeysHook` containing
+- `error`: An optional error object returned by Firebase
+- `loading`: A `boolean` to indicate if the listener is still being loaded
+- `value`: A list of `firebase.database.DataSnapshot.key` values
+
+```
+
+#### `useListVals<T>(ref, keyField)`
+
+Similar to `useList`, but this hook returns a typed list of the `DataSnapshot.val()` values, rather than the the
 `DataSnapshot`s themselves.
 
 Parameters:
 - `ref`: `firebase.database.Reference`
 - `keyField`: (Optional) Name of field that should be populated with the `DataSnapshot.key` property
 
 Returns:
-`ListValHook` containing
+`ListValsHook` containing
 - `error`: An optional error object returned by Firebase
 - `loading`: A `boolean` to indicate if the listener is still being loaded
-- `value`: A list of the contents of `firebase.database.DataSnapshot.val()` and optional key field
+- `value`: A list of `firebase.database.DataSnapshot.val()` values, combined with the optional key field
 
 ```
 

database/index.js.flow

@@ -6,7 +6,12 @@ export type ListHook = {
   loading: boolean;
   value: DataSnapshot[];
 };
-export type ListValHook<T> = {
+export type ListKeysHook<T> = {
+  error?: Object;
+  loading: boolean;
+  value: string[];
+};
+export type ListValsHook<T> = {
   error?: Object;
   loading: boolean;
   value: T[];
@@ -23,6 +28,7 @@ export type ObjectValHook<T> = {
 };
 
 declare export function useList(query: Query): ListHook;
-declare export function useListVal<T>(query: Query, keyField?: string): ListValHook<T>;
+declare export function useListKeys<T>(query: Query): ListKeysHook<T>;
+declare export function useListVals<T>(query: Query, keyField?: string): ListValsHook<T>;
 declare export function useObject(query: Query): ObjectHook;
 declare export function useObjectVal<T>(query: Query): ObjectValHook<T>;

database/index.ts

@@ -1,4 +1,4 @@
 export { default as useList, ListHook } from './useList';
-export { default as useListVal, ListValHook } from './useListVal';
+export { default as useListVals, ListValsHook } from './useListVals';
 export { default as useObject, ObjectHook } from './useObject';
 export { default as useObjectVal, ObjectValHook } from './useObjectVal';

database/useListKeys.ts

@@ -0,0 +1,17 @@
+import { database } from 'firebase';
+import useList from './useList';
+
+export type ListKeysHook<T> = {
+  error?: Object;
+  loading: boolean;
+  value: string[];
+};
+
+export default <T>(query: database.Query): ListKeysHook<T> => {
+  const { error, loading, value } = useList(query);
+  return {
+    error,
+    loading,
+    value: value.map(snapshot => snapshot.key),
+  };
+};

database/useListVal.ts renamed to database/useListVals.ts

@@ -1,7 +1,7 @@
 import { database } from 'firebase';
 import useList from './useList';
 
-export type ListValHook<T> = {
+export type ListValsHook<T> = {
   error?: Object;
   loading: boolean;
   value: T[];
@@ -10,7 +10,7 @@ export type ListValHook<T> = {
 export default <T>(
   query: database.Query,
   keyField?: string
-): ListValHook<T> => {
+): ListValsHook<T> => {
   const { error, loading, value } = useList(query);
   return {
     error,