Models¶

Model Fields¶

class chamber.models.fields.DecimalField¶

Same as django.db.models.DecimalField but with additional attributes. Uses chamber.forms.fields.DecimalField as the default form field.

min¶

A minimal value of the field. An appropriate MinValueValidator is added automatically. The HTML min component is added to the form field.

max¶

A maximal value of the field. An appropriate MaxValueValidator is added automatically. The HTML max component is added to the form field.

step¶

The step between values that is set on the form field.

class chamber.models.fields.RestrictedFileFieldMixin¶

Same as FileField, but you can specify:

allowed_content_types¶

A list containing allowed content types, e.g. ['application/pdf', 'image/jpeg']

max_upload_size¶

A number indicating the maximum file size allowed for upload in MB. The maximum upload size can be specified in project settings as MAX_FILE_UPLOAD_SIZE

class chamber.models.fields.FileField¶

The django.db.models.FileField with RestrictedFileFieldMixin options.

class chamber.models.fields.ImageField¶

sorl.thumbnail.ImageField with fallback to django.db.models.ImageField when sorl is not installed. Supports RestrictedFileFieldMixin options.

class chamber.models.fields.CharNullField¶

django.db.models.CharField that stores NULL but returns '' .

class chamber.models.fields.PriceField¶

chamber.models.fields.DecimalField with defaults:

currency¶

For example 'CZK'.

decimal_places¶

Number of digits reserved for the decimal part of the number.

max_digits¶

Max number of digits reserved for the field.

humanized¶

Humanized value for a pretty printing via chamber.models.humanized_helpers.price_humanized

class chamber.models.fields.PositivePriceField¶

chamber.models.fields.PriceField with a default django.core.validators.MinValueValidator set to 0.00.

class chamber.models.fields.SouthMixin¶

Mixin for automatic South migration of custom model fields.

SmartModel¶

chamber.models.SmartModel improved django Model class with several features that simplify development of complex applications

class chamber.models.SmartModel¶

created_at¶: Because our experience has shown us that datetime of creation is very useful this field django.models.DateTimeField with auto_add_no set to True is added to every model that inherits from SmartModel

changed_at¶: This model field is same case as created_at with the difference that there is used auto_now=True therefore every date and time of change is stored here.

dispatchers¶: List of defined pre or post save dispatchers. More obout it will find _dispatchers

clean_<field_name>(): Like a django form field you can use your own method named by field name for cleaning input value. You can too raise ValidationError if input value is invalid

_pre_save()¶: Method that is called before saving instance. You can here change instance structure or call some operations before saving object

_post_save()¶: Method that is called after saving instance. You can here change instance structure or call some operations after saving object

_pre_delete()¶: Method that is called before removing instance. You can here change instance structure or call some operations before removing object

_post_delete()¶: Method that is called after removing instance. You can here change instance structure or call some operations after removing object

refresh_from_db()¶: There is used implementation from django refresh_from_db method with small change that method returns refreshed instance

change(**changed_fields)¶: Update instance field values with values send in changed_fields

change_and_save(**changed_fields)¶: Update instance field values with values send in changed_fields and finally instance is saved

SmartMeta¶

SmartMeta similar like django meta is defined inside SmartModel and is accessible via _smart_meta attribute. Its purpose is define default SmartModel behavior.

class SmartMeta¶

is_cleaned_pre_save¶: Defines if SmartModel will be automatically validated before saving. Default value is True

is_cleaned_pre_save: Defines if SmartModel will be automatically validated after saving. Default value is False

is_cleaned_pre_delete¶: Defines if SmartModel will be automatically validated before removing. Default value is False

is_cleaned_pre_delete: Defines if SmartModel will be automatically validated after removing. Default value is False

is_save_atomic¶: Defines if SmartModel will be saved in transaction atomic block False

is_delete_atomic¶: Defines if SmartModel will be removed in transaction atomic block False

class SmartModelWithMeta(SmartModel):

    class SmartMeta:
        is_cleaned_pre_save = True
        is_cleaned_pre_delete = True

SmartQuerySet¶

SmartModel uses a modified QuerySet by default with some convenience filters.

If you are overriding model manager of a SmartModel, you should incorporate SmartQuerySet in order not to lose its benefits and to follow the Rule of the Least Surprise (everyone using your SmartModel will assume the custom filters to be there).

If the manager is created using the QuerySet.as_manager() method, your custom queryset should subclass SmartQuerySet instead the one from Django.
If you have a new manager created by subclassing models.Manager from Django, you should override the get_queryset method as shown in Django docs `here`_.

class chamber.models.SmartQuerySet¶

fast_distinct()¶

Returns same result as regular distinct() but is much faster especially in PostgreSQL which performs distinct on all DB columns. The optimization is achieved by doing a second query and the __in operator. If you have queryset qs of MyModel then fast_distinct() equals to calling

MyModel.objects.filter(pk__in=qs.values_list('pk', flat=True))

change_and_save(**changed_fields)¶: Change selected fields on the selected queryset and saves it, finnaly is returned changed objects in the queryset. Difference from update is that there is called save method on the instance, but it is slower.