Every morning, an online store receives the previous day’s orders from a marketplace partner.
The file comes in JSON format. The company needs to add those orders to its main MongoDB orders collection. The sales manager also needs a CSV report that can be opened in Excel.
That sounds like a small task. Import the file, copy the documents, export the report.
But in practice, a few things can break the process.
A date can be imported as a string. A field can have the wrong name. One batch may use total, while the main collection uses totalAmount. A temporary collection can keep old records and trigger duplicate key errors. A CSV export can create null values because the mapping points to fields that do not exist.
