Sub document refs undefined, when not populating in 4.0.2
Problem
I am having a strange issue [code block] Any properties that are refs never get added to the document, if I remove the 'ref' statement, the objects load just fine. I am NOT trying to populate the sub-document in this instance, I just want the sub-document id.
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1 Fix
Fix Undefined Sub Document Refs in Mongoose 4.0.2
In Mongoose 4.0.2, when defining a schema with references (refs) for sub-documents, if the sub-document is not populated, the ref property may cause the sub-document to not be included in the main document. This is due to Mongoose's handling of refs, which expects the referenced documents to be populated to include them in the output.
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- 1
Update Schema Definition
Modify the schema definition for the sub-document to ensure that it includes the necessary fields without relying on population. This can be done by defining a plain object instead of a ref.
javascriptconst subDocumentSchema = new mongoose.Schema({ id: { type: mongoose.Schema.Types.ObjectId, required: true } }); - 2
Use Lean Queries
When querying the main document, use the 'lean' method to retrieve plain JavaScript objects instead of Mongoose documents. This prevents Mongoose from attempting to populate refs unnecessarily.
javascriptModel.find().lean().exec((err, docs) => { /* handle docs */ }); - 3
Check for Mongoose Version Compatibility
Ensure that your Mongoose version is compatible with your MongoDB version and that there are no known issues with refs in the specific version you are using. If necessary, consider upgrading to a later version of Mongoose.
bashnpm install mongoose@latest - 4
Test Document Retrieval
After making the above changes, test the retrieval of documents to ensure that the sub-document IDs are now included in the main document without the need for population.
javascriptModel.find().then(docs => console.log(docs));
Validation
Confirm that the sub-document IDs are present in the main document output when querying without population. Check the console logs or the returned data structure for the expected IDs.
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Environment
Submitted by
Alex Chen
2450 rep