From 44623cc384ff13447c6cd84dd1a930a268d911a7 Mon Sep 17 00:00:00 2001
From: Faruk AYDIN <omerfaruk26@gmail.com>
Date: Thu, 10 Mar 2022 23:20:54 +0300
Subject: [PATCH] feat: Implement pagination logic and use with getExecutions
 query

---
 .../src/graphql/queries/get-executions.ts     | 14 ++++++---
 packages/backend/src/graphql/schema.graphql   | 16 +++++++++-
 packages/backend/src/helpers/pagination.ts    | 30 +++++++++++++++++++
 3 files changed, 55 insertions(+), 5 deletions(-)
 create mode 100644 packages/backend/src/helpers/pagination.ts

diff --git a/packages/backend/src/graphql/queries/get-executions.ts b/packages/backend/src/graphql/queries/get-executions.ts
index ed635650..2d41d722 100644
--- a/packages/backend/src/graphql/queries/get-executions.ts
+++ b/packages/backend/src/graphql/queries/get-executions.ts
@@ -1,16 +1,22 @@
 import Context from '../../types/express/context';
+import paginate from '../../helpers/pagination';
+
+type Params = {
+  limit: number;
+  offset: number;
+};
 
 const getExecutions = async (
   _parent: unknown,
-  _params: unknown,
+  params: Params,
   context: Context
 ) => {
-  const executions = await context.currentUser
+  const executions = context.currentUser
     .$relatedQuery('executions')
     .withGraphFetched('flow')
-    .orderBy('created_at', 'asc');
+    .orderBy('created_at', 'desc');
 
-  return executions;
+  return paginate(executions, params.limit, params.offset);
 };
 
 export default getExecutions;
diff --git a/packages/backend/src/graphql/schema.graphql b/packages/backend/src/graphql/schema.graphql
index 50b68224..ebe11b03 100644
--- a/packages/backend/src/graphql/schema.graphql
+++ b/packages/backend/src/graphql/schema.graphql
@@ -7,7 +7,7 @@ type Query {
   getFlow(id: String!): Flow
   getFlows: [Flow]
   getStepWithTestExecutions(stepId: String!): [Step]
-  getExecutions: [Execution]
+  getExecutions(limit: Int!, offset: Int!): ExecutionConnection
 }
 
 type Mutation {
@@ -354,6 +354,20 @@ type User {
   updatedAt: String
 }
 
+type PageInfo {
+  currentPage: Int!
+  totalPages: Int!
+}
+
+type ExecutionEdge {
+  node: Execution
+}
+
+type ExecutionConnection {
+  edges: [ExecutionEdge]
+  pageInfo: PageInfo
+}
+
 schema {
   query: Query
   mutation: Mutation
diff --git a/packages/backend/src/helpers/pagination.ts b/packages/backend/src/helpers/pagination.ts
new file mode 100644
index 00000000..b283dd93
--- /dev/null
+++ b/packages/backend/src/helpers/pagination.ts
@@ -0,0 +1,30 @@
+import { QueryBuilder, Model } from 'objection';
+
+const paginate = async (
+  query: QueryBuilder<Model, Model[]>,
+  limit: number,
+  offset: number
+) => {
+  if (limit < 1 || limit > 100) {
+    throw new Error('Limit must be between 1 and 100');
+  }
+
+  const [records, count] = await Promise.all([
+    query.limit(limit).offset(offset),
+    query.resultSize(),
+  ]);
+
+  return {
+    pageInfo: {
+      currentPage: Math.ceil(offset / limit + 1),
+      totalPages: Math.ceil(count / limit),
+    },
+    edges: records.map((record: Model) => {
+      return {
+        node: record,
+      };
+    }),
+  };
+};
+
+export default paginate;