mirror of
https://github.com/wagtail/wagtail.git
synced 2024-12-01 11:41:20 +01:00
72 lines
3.5 KiB
Markdown
72 lines
3.5 KiB
Markdown
(streamfield_validation)=
|
|
|
|
# StreamField validation
|
|
|
|
All StreamField blocks implement a `clean` method which accepts a block value and returns a cleaned version of that value, or raises a `ValidationError` if the value fails validation. Built-in validation rules, such as checking that a URLBlock value is a correctly-formatted URL, are implemented through this method. Additionally, for blocks that act as containers for other blocks, such as StructBlock, the `clean` method recursively calls the `clean` methods of its child blocks and handles raising validation errors back to the caller as required.
|
|
|
|
The `clean` method can be overridden on block subclasses to implement custom validation logic. For example, a StructBlock that requires either one of its child blocks to be filled in could be implemented as follows:
|
|
|
|
```python
|
|
from django.core.exceptions import ValidationError
|
|
from wagtail.blocks import StructBlock, PageChooserBlock, URLBlock
|
|
|
|
class LinkBlock(StructBlock):
|
|
page = PageChooserBlock(required=False)
|
|
url = URLBlock(required=False)
|
|
|
|
def clean(self, value):
|
|
result = super().clean(value)
|
|
if not(result['page'] or result['url']):
|
|
raise ValidationError("Either page or URL must be specified")
|
|
return result
|
|
```
|
|
|
|
## Controlling where error messages are rendered
|
|
|
|
In the above example, an exception of type `ValidationError` is raised, which causes the error to be attached and rendered against the StructBlock as a whole. For more control over where the error appears, the exception class `wagtail.blocks.StructBlockValidationError` can be raised instead. The constructor for this class accepts the following arguments:
|
|
|
|
- `non_block_errors` - a list of error messages or `ValidationError` instances to be raised against the StructBlock as a whole
|
|
- `block_errors` - a dict of `ValidationError` instances to be displayed against specific child blocks of the StructBlock, where the key is the child block's name
|
|
|
|
The following example demonstrates raising a validation error attached to the 'description' block within the StructBlock:
|
|
|
|
```python
|
|
from django.core.exceptions import ValidationError
|
|
from wagtail.blocks import CharBlock, StructBlock, StructBlockValidationError, TextBlock
|
|
|
|
class TopicBlock(StructBlock):
|
|
keyword = CharBlock()
|
|
description = TextBlock()
|
|
|
|
def clean(self, value):
|
|
result = super().clean(value)
|
|
if result["keyword"] not in result["description"]:
|
|
raise StructBlockValidationError(block_errors={
|
|
"description": ValidationError("Description must contain the keyword")
|
|
})
|
|
return result
|
|
```
|
|
|
|
ListBlock and StreamBlock also have corresponding exception classes `wagtail.blocks.ListBlockValidationError` and `wagtail.blocks.StreamBlockValidationError`, which work similarly, except that the keys of the `block_errors` dict are the numeric indexes of the blocks where the errors are to be attached:
|
|
|
|
```python
|
|
from django.core.exceptions import ValidationError
|
|
from wagtail.blocks import ListBlock, ListBlockValidationError
|
|
|
|
class AscendingListBlock(ListBlock):
|
|
# example usage:
|
|
# price_list = AscendingListBlock(FloatBlock())
|
|
|
|
def clean(self, value):
|
|
result = super().clean(value)
|
|
errors = {}
|
|
for i in range(1, len(result)):
|
|
if result[i] < result[i - 1]:
|
|
errors[i] = ValidationError("Values must be in ascending order")
|
|
|
|
if errors:
|
|
raise ListBlockValidationError(block_errors=errors)
|
|
|
|
return result
|
|
```
|