8.15. Inserting documents into MongoDB: Handling errors when inserting documents

MongoDB is a document-based NoSQL database, which means data is stored in a JSON-like structure. Inserting documents is a fundamental operation in MongoDB, and as such, it is crucial to understand how to handle errors that may occur during this process.

1. Inserting Documents

To insert a document into MongoDB, we use the 'insertOne()', 'insertMany()' or 'insert()' method. For example, to insert a single document into a collection called 'users', you could use the following code:

db.users.insertOne(
   {
      name: "John Doe",
      email: "john.doe@example.com",
      age: 30
   }
)

This code inserts a document with the fields 'name', 'email' and 'age' into the 'users' collection. If the operation is successful, MongoDB returns a result object that contains the '_id' of the inserted document.

2. Handling Errors when Inserting Documents

There are several errors that can occur when inserting documents into MongoDB. Here are some of the most common:

2.1. Schema Validation Error

If you are using MongoDB schema validation to enforce the structure of your documents, you may encounter validation errors if you try to insert a document that does not match the schema. To handle these errors, you can catch the exception and return an appropriate error message.

2.2. Key Duplication Error

MongoDB does not allow the insertion of two documents with the same value for a field that was indexed as unique. If you try to insert a document that violates this restriction, MongoDB will throw a key duplication error. This error can be handled by catching the exception and returning an appropriate error message.

2.3. Document Size Limit Error

MongoDB has a document size limit of 16 megabytes. If you try to insert a document that exceeds this limit, MongoDB will throw an error. To deal with this error, you can check the size of the document before trying to insert it, and if it is too large, split the document into several smaller documents.

3. Error Handling Examples

Here are some examples of how you can handle errors when inserting documents into MongoDB:

3.1. Schema Validation Error Handling

try {
   db.users.insertOne(
      {
         name: "John Doe",
         email: "john.doe@example.com",
         age: "30"
      }
   );
} catch (e) {
   if (e.name === 'MongoError' && e.code === 121) {
      console.error('Schema validation error: ', e.message);
   } else {
      throw e;
   }
}

3.2. Key Duplication Error Handling

try {
   db.users.insertOne(
      {
         _id: "123",
         name: "John Doe",
         email: "john.doe@example.com",
         age: 30
      }
   );
} catch (e) {
   if (e.name === 'MongoError' && e.code === 11000) {
      console.error('Key duplication error: ', e.message);
   } else {
      throw e;
   }
}

3.3. Document Size Limit Error Handling

try {
   var largeDocument = { /* a very large document */ };
   db.largeDocuments.insertOne(largeDocument);
} catch (e) {
   if (e.name === 'MongoError' && e.code === 10334) {
      console.error('Document size limit error: ', e.message);
   } else {
      throw e;
   }
}

Conclusion

Error handling is an essential part of inserting documents into MongoDB. By understanding the different types of errors that can occur and how to handle them, you can ensure that your application is robust and reliable.