Скачать или смотреть Resolving duplicate key errors in MongoDB during migration from Spring to Spring Boot

Encountering a `duplicate key error` when migrating your Spring application to Spring Boot? Learn how to resolve this issue by understanding MongoDB's ID handling and ensuring unique constraints are maintained throughout your data migrations.
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This video is based on the question https://stackoverflow.com/q/63519127/ asked by the user 'RVA' ( https://stackoverflow.com/u/3584279/ ) and on the answer https://stackoverflow.com/a/63647353/ provided by the user 'Peter Colclough' ( https://stackoverflow.com/u/1475131/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Resolving duplicate key errors in MongoDB during migration from Spring to Spring Boot

Migrating an application from an older version of Spring to a newer version of Spring Boot can introduce various challenges—especially when dealing with databases. One common issue that developers face is the dreaded duplicate key error when trying to migrate or update documents in MongoDB. In this guide, we'll explore this problem, specifically in the context of transitioning from spring-data-mongodb:1.10.18 to spring-data-mongodb:3.0.1.RELEASE, and provide a clear solution for how to address it.

The Problem: Encountering duplicate key error

During the migration process, you might encounter an error message similar to:

[[See Video to Reveal this Text or Code Snippet]]

This error typically points to a situation where you're attempting to insert a document into a MongoDB collection with an _id field that already exists, leading to duplication errors. This can particularly occur when you're manually defining an _id instead of allowing MongoDB to generate one for you.

The Code Changes: From Old to New

Let’s take a look at the code snippets associated with your migration:

Old Code (spring-data-mongodb:1.10.18):

[[See Video to Reveal this Text or Code Snippet]]

New Code (spring-data-mongodb:3.0.1.RELEASE):

[[See Video to Reveal this Text or Code Snippet]]

It becomes evident that in the new implementation, you're still using a manually constructed _id. This approach can lead to duplicate key errors if the keys have already been established in the MongoDB database.

Solution: Allow MongoDB to Generate Its Own _id

To resolve the duplicate key issue, you should allow MongoDB to handle the generation of unique IDs. Here’s a straightforward set of steps to follow:

1. Remove Manually Constructed IDs

Instead of constructing your own _id, simply let MongoDB create a unique identifier for each document when it is first inserted. Modify your code where you set the _id as follows:

[[See Video to Reveal this Text or Code Snippet]]

2. Add Your Unique Fields Separately

If you need custom fields, like storeID and productID, add them as separate fields rather than embedding them within the _id key. This retains the separation of concerns and avoids potential duplication errors.

[[See Video to Reveal this Text or Code Snippet]]

3. Update Logic for Transactions

After adjusting your ID handling, make sure that your MongoDB operations reflect these changes. For example, using a bulk insert or update might require updating your search queries for existing documents appropriately without relying on problematic _id structure.

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

By allowing MongoDB to manage its own identifiers and adjusting how you structure your documents, you can effectively eliminate duplicate key errors during your migration from Spring to Spring Boot. Remember, it is crucial not to replace the auto-generated _id field unless you have a solid plan for managing uniqueness across your data.

Following these guidelines will not only resolve your immediate migration issues but will also help you develop a more robust application architecture in the future. If you have more questions or run into other migration challenges, feel free to share your thoughts below!