Error Reference¶

DataJoint exception classes and their meanings.

Exception Hierarchy¶

Exception
└── DataJointError
    ├── LostConnectionError
    ├── QueryError
    │   ├── QuerySyntaxError
    │   ├── AccessError
    │   ├── DuplicateError
    │   ├── IntegrityError
    │   ├── UnknownAttributeError
    │   └── MissingAttributeError
    ├── MissingTableError
    ├── MissingExternalFile
    └── BucketInaccessible

Base Exception¶

DataJointError¶

Base class for all DataJoint-specific errors.

try:
    # DataJoint operation
except dj.DataJointError as e:
    print(f"DataJoint error: {e}")

Connection Errors¶

LostConnectionError¶

Database connection was lost during operation.

Common causes: - Network interruption - Server timeout - Server restart

Resolution: - Check network connectivity - Reconnect with dj.conn().connect()

Query Errors¶

QuerySyntaxError¶

Invalid query syntax.

Common causes: - Malformed restriction string - Invalid attribute reference - SQL syntax error in projection

AccessError¶

Insufficient database privileges.

Common causes: - User lacks SELECT/INSERT/DELETE privileges - Schema access not granted

Resolution: - Contact database administrator - Check user grants

DuplicateError¶

Attempt to insert duplicate primary key.

try:
    table.insert1({'id': 1, 'name': 'Alice'})
    table.insert1({'id': 1, 'name': 'Bob'})  # Raises DuplicateError
except dj.errors.DuplicateError:
    print("Entry already exists")

Resolution: - Use insert(..., skip_duplicates=True) - Use insert(..., replace=True) to update - Check if entry exists before inserting

IntegrityError¶

Foreign key constraint violation.

Common causes: - Inserting row with non-existent parent - Parent row deletion blocked by children

Resolution: - Insert parent rows first - Use cascade delete for parent

UnknownAttributeError¶

Referenced attribute doesn't exist.

# Raises UnknownAttributeError
table.to_arrays('nonexistent_column')

Resolution: - Check table.heading for available attributes - Verify spelling

MissingAttributeError¶

Required attribute not provided in insert.

# Raises MissingAttributeError if 'name' is required
table.insert1({'id': 1})  # Missing 'name'

Resolution: - Provide all required attributes - Set default values in definition

Table Errors¶

MissingTableError¶

Table not declared in database.

Common causes: - Schema not created - Table class not instantiated - Database dropped

Resolution: - Check schema exists: schema.is_activated() - Verify table declaration

Storage Errors¶

MissingExternalFile¶

External file managed by DataJoint is missing.

Common causes: - File manually deleted from store - Store misconfigured - Network/permission issues

Resolution: - Check store configuration - Verify file exists at expected path - Run garbage collection audit

BucketInaccessible¶

S3 bucket cannot be accessed.

Common causes: - Invalid credentials - Bucket doesn't exist - Network/firewall issues

Resolution: - Verify AWS credentials - Check bucket name and region - Test with AWS CLI

Handling Errors¶

Catching Specific Errors¶

import datajoint as dj

try:
    table.insert1(data)
except dj.errors.DuplicateError:
    print("Entry exists, skipping")
except dj.errors.IntegrityError:
    print("Parent entry missing")
except dj.DataJointError as e:
    print(f"Other DataJoint error: {e}")

Error Information¶

try:
    table.insert1(data)
except dj.DataJointError as e:
    print(f"Error type: {type(e).__name__}")
    print(f"Message: {e}")
    print(f"Args: {e.args}")