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Description

Error 241, 'Conversion Failure', indicates that MongoDB encountered an issue converting data from one type to another during an operation. This typically happens when data provided does not match the expected BSON type for a field, preventing the operation from completing successfully. This error signals an incompatibility in data representation.

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Error Message

Conversion Failure

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Known Causes

3 known causes

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Data Type Mismatch

An operation attempted to store or process data using an incompatible BSON data type for a specific field, such as inserting a string into a numeric field.

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Invalid BSON Serialization

The input data provided to MongoDB could not be properly serialized into a valid BSON format, leading to a conversion error during storage or retrieval.

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Schema Validation Violation

If schema validation is active for a collection, an operation might fail if the data type being inserted or updated violates the defined validation rules.

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Solutions

3 solutions available

1. Identify and Correct Mismatched Data Types During Updates medium

Find documents with incorrect data types for a specific field and update them to the expected type.

1

Identify documents where the data type of a specific field is incorrect. This often occurs when data is inserted or updated with a different type than expected. Use `db.collection.find()` with a query to target potential mismatches.

db.your_collection.find({ your_field: { $type: 'string' } }) // Example: find documents where 'your_field' is a string, but expected to be a number

2

Once identified, use `db.collection.updateMany()` to correct the data type. You might need to cast the existing value to the correct type.

db.your_collection.updateMany( { your_field: { $type: 'string' } }, [ { $set: { your_field: { $toInt: '$your_field' } } } ] ) // Example: convert string to integer

3

If the error persists, consider the possibility of mixed data types within the same field across different documents. You may need to iteratively fix these or perform a more complex data migration.

db.your_collection.find({ your_field: { $exists: true } }).forEach(function(doc) { if (typeof doc.your_field !== 'number') { try { doc.your_field = parseInt(doc.your_field); db.your_collection.save(doc); } catch (e) { print('Failed to convert document: ' + doc._id); } } });

2. Validate Data Before Insertion or Update medium

Implement schema validation to prevent data type inconsistencies from entering the database.

1

Define a schema validation rule for your collection using `db.createCollection()` or `db.runCommand()` with the `collMod` command. Specify the expected data type for each field.

db.createCollection('your_collection', {
  validator: {
    $jsonSchema: {
      bsonType: 'object',
      properties: {
        your_field: { bsonType: 'int', description: 'must be an integer and is required' },
        another_field: { bsonType: 'string', description: 'must be a string' }
      },
      required: ['your_field']
    }
  }
})

2

When inserting or updating documents, ensure the data conforms to the defined schema. MongoDB will reject documents that violate the validation rules, preventing Error 241.

db.your_collection.insertOne({ your_field: 123, another_field: 'hello' }) // Valid insertion
db.your_collection.insertOne({ your_field: 'abc', another_field: 'world' }) // This will fail due to type mismatch

3. Inspect Application Code for Type Casting Issues medium

Review your application's data handling logic to ensure correct type conversions before interacting with MongoDB.

1

Examine the code that performs insertions and updates to your MongoDB database. Look for instances where data is read from external sources (e.g., user input, APIs) and not explicitly converted to the correct MongoDB BSON types.

// Example in Node.js with a driver:
const valueFromApi = '123'; // This might be a string
const mongoValue = parseInt(valueFromApi); // Explicitly convert to integer before saving

2

Ensure that any string representations of numbers, dates, or other BSON types are correctly parsed and converted before being sent to the database. Use appropriate parsing functions provided by your programming language.

// Example in Python:
value_from_api = '2023-10-27T10:00:00Z'
datetime_object = datetime.fromisoformat(value_from_api.replace('Z', '+00:00')) # Convert to datetime object

3

If you are using an ORM or ODM, consult its documentation for best practices regarding data type handling and validation. They often provide mechanisms to enforce type consistency.

None

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Related Errors

5 related errors

MongoDB Error 241: Data Type Conversion Failure