refactoring: migrating to react-query to manage service-side state.

client/src/hooks/query/currencies.js

@@ -0,0 +1,41 @@
+import { useMutation, useQuery } from 'react-query';
+import ApiService from 'services/ApiService';
+
+/**
+ * Create a new currency.
+ */
+export function useCreateCurrency() {
+  return useMutation((values) => ApiService.post('currencies', values));
+}
+
+/**
+ * Edits the given currency code.
+ */
+export function useEditCurrency() {
+  return useMutation((currencyCode, values) =>
+    ApiService.post(`currencies/${currencyCode}`, values),
+  );
+}
+
+/**
+ * Deletes the given currency.
+ */
+export function useDeleteCurrency() {
+  return useMutation((currencyCode) =>
+    ApiService.delete(`currencies/${currencyCode}`),
+  );
+}
+
+/**
+ * Retrieve the currencies list.
+ */
+export function useCurrencies(props) {
+  return useQuery(
+    ['CURRENCIES'],
+    () => ApiService.get('currencies').then(res => res.data.currencies),
+    {
+      initialData: [],
+      ...props,
+    },
+  );
+}