Fetch existing subscription if create fails as already exists

guides/Getting Started.md

@@ -4,24 +4,24 @@ EventStore is [available in Hex](https://hex.pm/packages/eventstore) and can be
 
   1. Add eventstore to your list of dependencies in `mix.exs`:
 
-    ```elixir    
-    def deps do
-      [{:eventstore, "~> 0.13"}]
-    end
-    ```
+      ```elixir    
+      def deps do
+        [{:eventstore, "~> 0.13"}]
+      end
+      ```
 
   2. Add an `eventstore` config entry containing the PostgreSQL database connection details to each environment's mix config file (e.g. `config/dev.exs`):
 
-    ```elixir
-    config :eventstore, EventStore.Storage,
-      serializer: EventStore.TermSerializer,
-      username: "postgres",
-      password: "postgres",
-      database: "eventstore_dev",
-      hostname: "localhost",
-      pool_size: 10,
-      pool_overflow: 5
-    ```
+      ```elixir
+      config :eventstore, EventStore.Storage,
+        serializer: EventStore.TermSerializer,
+        username: "postgres",
+        password: "postgres",
+        database: "eventstore_dev",
+        hostname: "localhost",
+        pool_size: 10,
+        pool_overflow: 5
+      ```
 
   The database connection pool configuration options are:
 
@@ -30,9 +30,9 @@ EventStore is [available in Hex](https://hex.pm/packages/eventstore) and can be
 
   3. Create the EventStore database and tables using the `mix` task:
 
-    ```console
-    $ mix do event_store.create, event_store.init
-    ```
+      ```console
+      $ mix do event_store.create, event_store.init
+      ```
 
 ## Initialize an existing database
 

lib/event_store/storage/subscription.ex

@@ -35,7 +35,7 @@ defmodule EventStore.Storage.Subscription do
       {:ok, subscription}
     else
       {:error, :subscription_not_found} ->
-        Subscription.Subscribe.execute(conn, stream_uuid, subscription_name, start_from, opts)
+        create_subscription(conn, stream_uuid, subscription_name, start_from, opts)
 
       reply ->
         reply
@@ -52,9 +52,19 @@ defmodule EventStore.Storage.Subscription do
   def unsubscribe_from_stream(conn, stream_uuid, subscription_name, opts \\ []),
     do: Subscription.Unsubscribe.execute(conn, stream_uuid, subscription_name, opts)
 
+  defp create_subscription(conn, stream_uuid, subscription_name, start_from, opts) do
+    case Subscription.Subscribe.execute(conn, stream_uuid, subscription_name, start_from, opts) do
+      {:error, :subscription_already_exists} ->
+        Subscription.Query.execute(conn, stream_uuid, subscription_name, opts)
+
+      reply ->
+        reply
+    end
+  end
+
   defmodule All do
     @moduledoc false
-    
+
     def execute(conn, opts) do
       conn
       |> Postgrex.query(Statements.query_all_subscriptions, [], opts)