Add PageChooserBlock target_model option

It allows selecting a restricted subset of pages, like with the
PageChooserPanel

docs/topics/streamfield.rst

@@ -242,6 +242,9 @@ A control for selecting a page object, using Wagtail's page browser. The followi
 ``required`` (default: True)
   If true, the field cannot be left blank.
 
+``target_model`` (default: Page)
+  Restrict choices to a single Page type.
+
 ``can_choose_root`` (default: False)
   If true, the editor can choose the tree root as a page. Normally this would be undesirable, since the tree root is never a usable page, but in some specialised cases it may be appropriate. For example, a block providing a feed of related articles could use a PageChooserBlock to select which subsection of the site articles will be taken from, with the root corresponding to 'everywhere'.
 

wagtail/wagtailcore/blocks/field_block.py

@@ -13,6 +13,7 @@ from django.utils.html import format_html
 from django.utils.safestring import mark_safe
 
 from wagtail.wagtailcore.rich_text import RichText
+from wagtail.wagtailcore.utils import resolve_model_string
 
 from .base import Block
 
@@ -530,19 +531,21 @@ class ChooserBlock(FieldBlock):
 
 class PageChooserBlock(ChooserBlock):
 
-    def __init__(self, can_choose_root=False, **kwargs):
+    def __init__(self, target_model='wagtailcore.Page', can_choose_root=False,
+                 **kwargs):
+        self._target_model = target_model
         self.can_choose_root = can_choose_root
         super(PageChooserBlock, self).__init__(**kwargs)
 
     @cached_property
     def target_model(self):
-        from wagtail.wagtailcore.models import Page  # TODO: allow limiting to specific page types
-        return Page
+        return resolve_model_string(self._target_model)
 
     @cached_property
     def widget(self):
         from wagtail.wagtailadmin.widgets import AdminPageChooser
-        return AdminPageChooser(can_choose_root=self.can_choose_root)
+        return AdminPageChooser(target_models=[self.target_model],
+                                can_choose_root=self.can_choose_root)
 
     def render_basic(self, value, context=None):
         if value:
@@ -550,6 +553,13 @@ class PageChooserBlock(ChooserBlock):
         else:
             return ''
 
+    def deconstruct(self):
+        name, args, kwargs = super(PageChooserBlock, self).deconstruct()
+        if 'target_model' in kwargs:
+            opts = self.target_model._meta
+            kwargs['target_model'] = '{}.{}'.format(opts.app_label, opts.object_name)
+        return name, args, kwargs
+
     class Meta:
         icon = "redirect"
 

wagtail/wagtailcore/tests/test_blocks.py

@@ -20,6 +20,7 @@ from django.utils.translation import ugettext_lazy as __
 
 from wagtail.tests.testapp.blocks import LinkBlock as CustomLinkBlock
 from wagtail.tests.testapp.blocks import SectionBlock
+from wagtail.tests.testapp.models import SimplePage
 from wagtail.wagtailcore import blocks
 from wagtail.wagtailcore.models import Page
 from wagtail.wagtailcore.rich_text import RichText
@@ -2036,6 +2037,11 @@ class TestPageChooserBlock(TestCase):
         self.assertIn(expected_html, christmas_form_html)
         self.assertIn("pick a page, any page", christmas_form_html)
 
+    def test_form_render_with_target_model(self):
+        block = blocks.PageChooserBlock(help_text="pick a page, any page", target_model='tests.SimplePage')
+        empty_form_html = block.render_form(None, 'page')
+        self.assertIn('createPageChooser("page", ["tests.simplepage"], null, false);', empty_form_html)
+
     def test_form_render_with_can_choose_root(self):
         block = blocks.PageChooserBlock(help_text="pick a page, any page", can_choose_root=True)
         empty_form_html = block.render_form(None, 'page')
@@ -2063,6 +2069,26 @@ class TestPageChooserBlock(TestCase):
         self.assertEqual(nonrequired_block.clean(christmas_page), christmas_page)
         self.assertEqual(nonrequired_block.clean(None), None)
 
+    def test_target_model_string(self):
+        block = blocks.PageChooserBlock(target_model='tests.SimplePage')
+        self.assertEqual(block.target_model, SimplePage)
+
+    def test_target_model_literal(self):
+        block = blocks.PageChooserBlock(target_model=SimplePage)
+        self.assertEqual(block.target_model, SimplePage)
+
+    def test_deconstruct_target_model_string(self):
+        block = blocks.PageChooserBlock(target_model='tests.SimplePage')
+        self.assertEqual(block.deconstruct(), (
+            'wagtail.wagtailcore.blocks.PageChooserBlock',
+            (), {'target_model': 'tests.SimplePage'}))
+
+    def test_deconstruct_target_model_literal(self):
+        block = blocks.PageChooserBlock(target_model=SimplePage)
+        self.assertEqual(block.deconstruct(), (
+            'wagtail.wagtailcore.blocks.PageChooserBlock',
+            (), {'target_model': 'tests.SimplePage'}))
+
 
 class TestSystemCheck(TestCase):
     def test_name_must_be_nonempty(self):