Initial reader-api backend extracted from reader

lib/mongoose.ts

@@ -0,0 +1,39 @@
+import mongoose from "mongoose"
+
+let cached = (global as any).mongoose
+
+if (!cached) {
+    cached = (global as any).mongoose = { conn: null, promise: null }
+}
+
+async function connectToMongoDB() {
+    const mongodbUri = process.env.MONGODB_URI
+    if (!mongodbUri) {
+        throw new Error("Please define the MONGODB_URI environment variable")
+    }
+
+    if (cached.conn) {
+        return cached.conn
+    }
+
+    if (!cached.promise) {
+        const opts = {
+            bufferCommands: false,
+        }
+
+        cached.promise = mongoose.connect(mongodbUri, opts).then((mongoose) => {
+            return mongoose
+        })
+    }
+
+    try {
+        cached.conn = await cached.promise
+    } catch (e) {
+        cached.promise = null
+        throw e
+    }
+
+    return cached.conn
+}
+
+export default connectToMongoDB