Reference Databases

MySQL and MariaDB do not support some options to the SELECT ... FOR UPDATE statement. If select_for_update() is used with an unsupported option, then a NotSupportedError is raised.

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Reference Databases MySQL notes

MySQL and MariaDB do not support some options to the SELECT ... FOR UPDATE statement. If select_for_update() is used with an unsupported option, then a NotSupportedError is raised.

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Reference Widgets

Widgets inheriting from the Select widget deal with choices. They present the user with a list of options to choose from.

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Topic guide Templates Support for template engines

Template objects returned by get_template() and select_template() must provide a render() method with the following signature: Template.render(context=None,request=None) : Renders this template with a given context. Here’s an example of the search algorithm.

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Reference Form fields Built-in Field classes

classChoiceField(**kwargs)[source] : - Default widget: Select - Empty value: '' (an empty string) - Normalizes to: A string. - Validates that the given value exists in the list of choices. - Error message keys: required, invalid_choice

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Reference Form fields Built-in Field classes

classFilePathField(**kwargs)[source] : - Default widget: Select - Empty value: '' (an empty string) - Normalizes to: A string. - Validates that the selected choice exists in the list of choices. - Error message keys: required, invalid_choice

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Reference Form fields Fields which handle relationships

classModelChoiceField(**kwargs)[source] : - Default widget: Select - Empty value: None - Normalizes to: A model instance. - Validates that the given id exists in the queryset. - Error message keys: required, invalid_choice

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Reference Widgets Built-in widgetsSelector and checkbox widgets

classNullBooleanSelect[source] : - template_name: 'django/forms/widgets/select.html' - option_template_name: 'django/forms/widgets/select_option.html'

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Reference Widgets Built-in widgetsSelector and checkbox widgets

classSelectMultiple[source] : - template_name: 'django/forms/widgets/select.html' - option_template_name: 'django/forms/widgets/select_option.html'

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Reference Widgets Built-in widgetsComposite widgets

classSelectDateWidget[source] : - template_name: 'django/forms/widgets/select_date.html'

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Reference QuerySet API reference

extra(select=None,where=None,params=None,tables=None,order_by=None,select_params=None) Sometimes, the Django query syntax by itself can’t easily express a complex WHERE clause. For these edge cases, Django provides the extra() QuerySet modifier — a hook for injecting specific clauses into the SQL generated by a QuerySet.

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Topic guide Multiple databases

You can select the database for a QuerySet at any point in the QuerySet “chain.” Call using() on the QuerySet to get another QuerySet that uses the specified database.

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Topic guide Translation

If you want to select a language within a template, you can use the language template tag: While the first occurrence of “Welcome to our page” uses the current language, the second will always be in English.

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Reference QuerySet API reference QuerySet APIMethods that return new QuerySets

extra(select=None,where=None,params=None,tables=None,order_by=None,select_params=None) Sometimes, the Django query syntax by itself can’t easily express a complex WHERE clause. For these edge cases, Django provides the extra() QuerySet modifier — a hook for injecting specific clauses into the SQL generated by a QuerySet.

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Topic guide Multiple databases Manually selecting a database

You can select the database for a QuerySet at any point in the QuerySet “chain.” Call using() on the QuerySet to get another QuerySet that uses the specified database.

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Topic guide Translation Internationalization: in template code

If you want to select a language within a template, you can use the language template tag: While the first occurrence of “Welcome to our page” uses the current language, the second will always be in English.

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Reference Widgets Built-in widgetsSelector and checkbox widgets

classCheckboxSelectMultiple[source] : - template_name: 'django/forms/widgets/checkbox_select.html' - option_template_name: 'django/forms/widgets/checkbox_option.html' Like RadioSelect, you can loop over the individual checkboxes for the widget’s choices.

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Reference QuerySet API reference

Greater than. Example: SQL equivalent:

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Reference QuerySet API reference QuerySet APIField lookups

Greater than. Example: SQL equivalent:

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Reference Form fields

classChoiceField(**kwargs)[source] : - Default widget: Select - Empty value: '' (an empty string) - Normalizes to: A string. - Validates that the given value exists in the list of choices. - Error message keys: required, invalid_choice

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