Zope Container

Common errors

• ImportError: No module named 'zope.container.old_module'

  cause An import path for a Zope component has changed, or a compatibility import has been removed in a newer version of `zope.container` or a related Zope package.
  fix Consult the `zope.container` changelog or the documentation for the specific Zope package that the module belongs to. For example, `IContained` moved to `zope.location.interfaces` in older versions.

• TypeError: ('Could not adapt', <object>, <Interface>)

  cause This often indicates a mismatch in interface declarations or an object not properly implementing a required interface, especially after updates to `zope.interface` or related Zope packages.
  fix Verify that all classes intended to implement `zope.container` interfaces (like `IContainer`, `IWriteContainer`) correctly use the `@implementer` decorator from `zope.interface` and that the object itself is registered or configured to be adaptable. Ensure `zope.interface` and other Zope packages are compatible versions.

• KeyError: 'item_name' or ValueError: 'Invalid item name'

  cause In modern versions (>=3.7.1), `zope.container` raises standard `KeyError` for duplication or missing keys and `ValueError` for invalid input (e.g., empty or disallowed characters in names) during item addition/retrieval.
  fix Ensure that keys used for adding or accessing items in a container are unique and adhere to naming conventions (e.g., non-empty, valid string characters). Handle `KeyError` for non-existent items or `ValueError` for invalid names.

Warnings

• breaking Major versions of `zope.container` (e.g., 5.0, 6.0, 7.0, 7.1) frequently drop support for older Python versions. Ensure your environment meets the `requires_python` specification (currently >=3.10 for 7.2).
  Fix: Upgrade your Python interpreter to a supported version or pin `zope-container` to an older version compatible with your Python environment. Refer to PyPI for specific version requirements.
• breaking Version 7.0 of `zope.container` (and other Zope packages) migrated from `pkg_resources` to PEP 420 native namespace packages. This can affect how sub-packages are discovered and imported in complex Zope deployments.
  Fix: Ensure your project's packaging and import mechanisms are compatible with PEP 420 namespace packages. This is typically handled automatically by modern Python packaging tools, but older setups might require adjustment.
• breaking Older versions of `zope.interface` (a core dependency) had significant breaking changes in version 6.0 and 7.0, including the removal of deprecated `implements` and `classProvides` functions in favor of `@implementer` and `@provider` decorators. Although `zope.container` itself adopted these earlier (e.g., 4.0.0a1 for `implementer`), downstream code might break.
  Fix: Update code that declares interfaces or implementations to use the `@implementer` and `@provider` decorators from `zope.interface`. For example, replace `implements(IMyInterface)` with `@implementer(IMyInterface)`.
• gotcha Before `zope.container` version 3.7.1, certain container operations raised custom exceptions like `zope.exceptions.DuplicationError` or `zope.exceptions.UserError`. These were changed to standard Python exceptions `KeyError` and `ValueError` respectively.
  Fix: If working with very old code or migrating from it, update exception handling to catch `KeyError` and `ValueError` instead of the former `zope.exceptions` types.

Install

• pip install zope-container Install latest version

Imports

• BTreeContainer

  from zope.container.btree import BTreeContainer

• OrderedContainer

  from zope.container.ordered import OrderedContainer

• IContainer

  from zope.container.interfaces import IContainer

• IWriteContainer

  from zope.container.interfaces import IWriteContainer

Quickstart

This quickstart demonstrates creating a basic BTreeContainer, implementing IContainer (a common pattern in Zope to declare interface adherence), and then adding and retrieving items. This showcases the core container functionality.

from zope.container.btree import BTreeContainer
from zope.interface import implementer
from zope.container.interfaces import IContainer

@implementer(IContainer)
class MyContainer(BTreeContainer):
    """A simple container demonstrating zope.container."""
    pass


container = MyContainer()
container['item1'] = 'First Value'
container['item2'] = 123

print(f"Container has {len(container)} items.")
print(f"Item 1: {container['item1']}")

# Iterating through a container
for key, value in container.items():
    print(f"Key: {key}, Value: {value}")