Cache mechanism for imports. Due to complications of circular imports mongoengine needs to do lots of inline imports in functions. This is inefficient as classes are imported repeated throughout the mongoengine code. This is compounded by some recursive functions requiring inline
(cls_name)
| 3 | |
| 4 | |
| 5 | def _import_class(cls_name): |
| 6 | """Cache mechanism for imports. |
| 7 | |
| 8 | Due to complications of circular imports mongoengine needs to do lots of |
| 9 | inline imports in functions. This is inefficient as classes are |
| 10 | imported repeated throughout the mongoengine code. This is |
| 11 | compounded by some recursive functions requiring inline imports. |
| 12 | |
| 13 | :mod:`mongoengine.common` provides a single point to import all these |
| 14 | classes. Circular imports aren't an issue as it dynamically imports the |
| 15 | class when first needed. Subsequent calls to the |
| 16 | :func:`~mongoengine.common._import_class` can then directly retrieve the |
| 17 | class from the :data:`mongoengine.common._class_registry_cache`. |
| 18 | """ |
| 19 | if cls_name in _class_registry_cache: |
| 20 | return _class_registry_cache.get(cls_name) |
| 21 | |
| 22 | doc_classes = ( |
| 23 | "Document", |
| 24 | "DynamicEmbeddedDocument", |
| 25 | "EmbeddedDocument", |
| 26 | "MapReduceDocument", |
| 27 | ) |
| 28 | |
| 29 | # Field Classes |
| 30 | if not _field_list_cache: |
| 31 | from mongoengine.fields import __all__ as fields |
| 32 | |
| 33 | _field_list_cache.extend(fields) |
| 34 | from mongoengine.base.fields import __all__ as fields |
| 35 | |
| 36 | _field_list_cache.extend(fields) |
| 37 | |
| 38 | field_classes = _field_list_cache |
| 39 | |
| 40 | deref_classes = ("DeReference",) |
| 41 | |
| 42 | if cls_name == "BaseDocument": |
| 43 | from mongoengine.base import document as module |
| 44 | |
| 45 | import_classes = ["BaseDocument"] |
| 46 | elif cls_name in doc_classes: |
| 47 | from mongoengine import document as module |
| 48 | |
| 49 | import_classes = doc_classes |
| 50 | elif cls_name in field_classes: |
| 51 | from mongoengine import fields as module |
| 52 | |
| 53 | import_classes = field_classes |
| 54 | elif cls_name in deref_classes: |
| 55 | from mongoengine import dereference as module |
| 56 | |
| 57 | import_classes = deref_classes |
| 58 | else: |
| 59 | raise ValueError("No import set for: %s" % cls_name) |
| 60 | |
| 61 | for cls in import_classes: |
| 62 | _class_registry_cache[cls] = getattr(module, cls) |