material numbers defined as string, colors without numbers can be added

src/models/material.ts

@@ -9,9 +9,9 @@ const MaterialSchema = new mongoose.Schema({
   carbon_fiber: String,
   numbers: [{
     color: String,
-    number: Number
+    number: String
   }],
   status: Number
-});
+}, {minimize: false});
 
 export default mongoose.model('material', MaterialSchema);