From fac6fea2e6186f12de8d3ab889bebb2f3a01f8d7 Mon Sep 17 00:00:00 2001
From: Guillaume Chau <alphadelta.fg@gmail.com>
Date: Sun, 1 Dec 2019 02:35:37 +0100
Subject: [PATCH] feat(useQuery): onResult & onError

---
 .../vue-apollo-composable/src/useQuery.ts     |  8 ++++-
 .../src/util/useEventHook.ts                  | 29 +++++++++++++++++++
 2 files changed, 36 insertions(+), 1 deletion(-)
 create mode 100644 packages/vue-apollo-composable/src/util/useEventHook.ts

diff --git a/packages/vue-apollo-composable/src/useQuery.ts b/packages/vue-apollo-composable/src/useQuery.ts
index 094b46a7..b755a459 100644
--- a/packages/vue-apollo-composable/src/useQuery.ts
+++ b/packages/vue-apollo-composable/src/useQuery.ts
@@ -42,7 +42,9 @@ export function useQuery<
    * Result from the query
    */
   const result = ref<TResult>()
-  const error = ref(null)
+  const resultEvent = useEventHook<ApolloQueryResult<TResult>>()
+  const error = ref<Error>(null)
+  const errorEvent = useEventHook<Error>()
 
   // Loading
 
@@ -92,12 +94,14 @@ export function useQuery<
     result.value = queryResult.data
     loading.value = queryResult.loading
     networkStatus.value = queryResult.networkStatus
+    resultEvent.trigger(queryResult)
   }
 
   function onError (queryError: any) {
     error.value = queryError
     loading.value = false
     networkStatus.value = 8
+    errorEvent.trigger(queryError)
   }
 
   let onStopHandlers: (() => void)[] = []
@@ -260,5 +264,7 @@ export function useQuery<
     query,
     refetch,
     subscribeToMore,
+    onResult: resultEvent.on,
+    onError: errorEvent.on,
   }
 }
diff --git a/packages/vue-apollo-composable/src/util/useEventHook.ts b/packages/vue-apollo-composable/src/util/useEventHook.ts
new file mode 100644
index 00000000..6d8b3b3f
--- /dev/null
+++ b/packages/vue-apollo-composable/src/util/useEventHook.ts
@@ -0,0 +1,29 @@
+export function useEventHook<TParam = any> () {
+  const fns: ((param?: TParam) => void)[] = []
+
+  function on (fn: (param?: TParam) => void) {
+    fns.push(fn)
+    return {
+      off: () => off(fn),
+    }
+  }
+
+  function off (fn: (param?: TParam) => void) {
+    const index = fns.indexOf(fn)
+    if (index !== -1) {
+      fns.splice(index, 1)
+    }
+  }
+
+  function trigger (param?: TParam) {
+    for (const fn of fns) {
+      fn(param)
+    }
+  }
+
+  return {
+    on,
+    off,
+    trigger,
+  }
+}
\ No newline at end of file