Updated new pagination feature. (#523)

Author: Antoliny0919

ratings/tests/migrations/__init__.py renamed to base/__init__.py

@@ -0,0 +1,6 @@
+class IncorectLookupParameter(Exception):
+    """
+    Raised when a query parameter contains an incorrect value.
+    """
+
+    pass

base/exceptions.py

@@ -0,0 +1,58 @@
+from django.core.paginator import InvalidPage, Paginator
+
+from .exceptions import IncorectLookupParameter
+
+PAGE_VAR = "page"
+
+
+class Pagination:
+    def __init__(
+        self,
+        request,
+        model,
+        queryset,
+        list_per_page,
+    ):
+        self.model = model
+        self.opts = model._meta
+        self.queryset = queryset
+        self.list_per_page = list_per_page
+        try:
+            # Get the current page from the query string.
+            self.page_num = int(request.GET.get(PAGE_VAR, 1))
+        except ValueError:
+            self.page_num = 1
+        self.params = dict(request.GET.lists())
+        self.setup()
+
+    @property
+    def page_range(self):
+        """
+        Returns the full range of pages.
+        """
+        return (
+            self.paginator.get_elided_page_range(self.page_num)
+            if self.multi_page
+            else []
+        )
+
+    def setup(self):
+        paginator = Paginator(self.queryset, self.list_per_page)
+        result_count = paginator.count
+        # Determine use pagination.
+        multi_page = result_count > self.list_per_page
+
+        self.result_count = result_count
+        self.multi_page = multi_page
+        self.paginator = paginator
+        self.page = paginator.get_page(self.page_num)
+
+    def get_objects(self):
+        if not self.multi_page:
+            result_list = self.queryset._clone()
+        else:
+            try:
+                result_list = self.paginator.page(self.page_num).object_list
+            except InvalidPage:
+                raise IncorectLookupParameter
+        return result_list

base/migrations/__init__.py

@@ -0,0 +1,69 @@
+from collections.abc import Iterable, Mapping
+
+from django import template
+from django.http import QueryDict
+from django.template.exceptions import TemplateSyntaxError
+
+register = template.Library()
+
+
+# This template tag is scheduled to be added in Django 6.0.
+# Imported for use before the release of Django 6.0.
+@register.simple_tag(name="querystring", takes_context=True)
+def querystring(context, *args, **kwargs):
+    """
+    Build a query string using `args` and `kwargs` arguments.
+
+    This tag constructs a new query string by adding, removing, or modifying
+    parameters from the given positional and keyword arguments. Positional
+    arguments must be mappings (such as `QueryDict` or `dict`), and
+    `request.GET` is used as the starting point if `args` is empty.
+
+    Keyword arguments are treated as an extra, final mapping. These mappings
+    are processed sequentially, with later arguments taking precedence.
+
+    A query string prefixed with `?` is returned.
+
+    Raise TemplateSyntaxError if a positional argument is not a mapping or if
+    keys are not strings.
+
+    For example::
+
+        {# Set a parameter on top of `request.GET` #}
+        {% querystring foo=3 %}
+
+        {# Remove a key from `request.GET` #}
+        {% querystring foo=None %}
+
+        {# Use with pagination #}
+        {% querystring page=page_obj.next_page_number %}
+
+        {# Use a custom ``QueryDict`` #}
+        {% querystring my_query_dict foo=3 %}
+
+        {# Use multiple positional and keyword arguments #}
+        {% querystring my_query_dict my_dict foo=3 bar=None %}
+    """
+    if not args:
+        args = [context.request.GET]
+    params = QueryDict(mutable=True)
+    for d in [*args, kwargs]:
+        if not isinstance(d, Mapping):
+            raise TemplateSyntaxError(
+                "querystring requires mappings for positional arguments (got "
+                "%r instead)." % d
+            )
+        for key, value in d.items():
+            if not isinstance(key, str):
+                raise TemplateSyntaxError(
+                    "querystring requires strings for mapping keys (got %r "
+                    "instead)." % key
+                )
+            if value is None:
+                params.pop(key, None)
+            elif isinstance(value, Iterable) and not isinstance(value, str):
+                params.setlist(key, value)
+            else:
+                params[key] = value
+    query_string = params.urlencode() if params else ""
+    return f"?{query_string}"

base/pagination.py

@@ -0,0 +1,40 @@
+from django import template
+from django.utils.html import format_html
+from django.utils.safestring import mark_safe
+
+from base.pagination import PAGE_VAR
+
+from .base_templatetags import querystring
+
+register = template.Library()
+
+
+@register.simple_tag
+def pagination_number(pagination, i):
+    """
+    Generate an individual page index link in a paginated list.
+    """
+    if i == pagination.paginator.ELLIPSIS:
+        return format_html("{} ", pagination.paginator.ELLIPSIS)
+    elif i == pagination.page_num:
+        return format_html('<em class="current-page" aria-current="page">{}</em> ', i)
+    else:
+        link = querystring(None, pagination.params, {PAGE_VAR: i})
+        return format_html(
+            '<a href="{}" aria-label="page {}" {}>{}</a> ',
+            link,
+            i,
+            mark_safe(' class="end"' if i == pagination.paginator.num_pages else ""),
+            i,
+        )
+
+
+@register.inclusion_tag("base/components/pagination.html", name="pagination")
+def pagination_tag(pagination):
+    previous_page_link = f"?{PAGE_VAR}={pagination.page_num - 1}"
+    next_page_link = f"?{PAGE_VAR}={pagination.page_num + 1}"
+    return {
+        "pagination": pagination,
+        "previous_page_link": previous_page_link,
+        "next_page_link": next_page_link,
+    }

base/templatetags/__init__.py

@@ -0,0 +1,21 @@
+# Generated by Django 3.2.15 on 2025-06-04 05:19
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('tests', '0001_initial'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='Fish',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('name', models.CharField(max_length=255)),
+                ('price', models.IntegerField()),
+            ],
+        ),
+    ]

base/templatetags/base_templatetags.py

@@ -1,6 +1,11 @@
 from django.db import models
 
-from ..models import RatedItemBase, Ratings
+from ratings.models import RatedItemBase, Ratings
+
+
+class Fish(models.Model):
+    name = models.CharField(max_length=255)
+    price = models.IntegerField()
 
 
 class Food(models.Model):

base/templatetags/components.py

@@ -0,0 +1,60 @@
+from django.test import RequestFactory, TestCase
+
+from base.pagination import Pagination
+
+from .models import Fish
+
+
+class PaginationTestCase(TestCase):
+    @classmethod
+    def setUpTestData(cls):
+        fishs = [Fish(name=f"fish-{i}", price=i * 100) for i in range(1, 101)]
+        Fish.objects.bulk_create(fishs)
+        cls.queryset = Fish.objects.all()
+        cls.factory = RequestFactory()
+
+    def test_pagination_attributes(self):
+        request = self.factory.get("/fake-url/")
+        pagination = Pagination(request, Fish, self.queryset, 5)
+        self.assertEqual(pagination.result_count, 100)
+        self.assertTrue(pagination.multi_page)
+        pagination = Pagination(request, Fish, self.queryset, 200)
+        self.assertFalse(pagination.multi_page)
+
+    def test_pagination_page_range(self):
+        request = self.factory.get("/fake-url/")
+        ELLIPSIS = "…"
+        case = [
+            (2, 6, [1, 2, 3, 4, 5, 6, 7, 8, 9, ELLIPSIS, 49, 50]),
+            (3, 10, [1, 2, ELLIPSIS, 7, 8, 9, 10, 11, 12, 13, ELLIPSIS, 33, 34]),
+            (4, 23, [1, 2, ELLIPSIS, 20, 21, 22, 23, 24, 25]),
+            (5, 20, [1, 2, ELLIPSIS, 17, 18, 19, 20]),
+            (10, 8, [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]),
+            (20, 1, [1, 2, 3, 4, 5]),
+        ]
+        for list_per_page, current_page, expected_page_range in case:
+            with self.subTest(list_per_page=list_per_page, current_page=current_page):
+                pagination = Pagination(request, Fish, self.queryset, list_per_page)
+                pagination.page_num = current_page
+                self.assertEqual(list(pagination.page_range), expected_page_range)
+
+    def test_pagination_result_objects(self):
+        request = self.factory.get("/fake-url/")
+        case = [
+            (2, 25, ["49", "50"]),
+            (4, 12, ["45", "46", "47", "48"]),
+            (5, 10, ["46", "47", "48", "49", "50"]),
+            (7, 11, ["71", "72", "73", "74", "75", "76", "77"]),
+            (10, 10, ["91", "92", "93", "94", "95", "96", "97", "98", "99", "100"]),
+            (200, 1, [str(i) for i in range(1, 101)]),
+        ]
+        Fish.objects.all().delete()
+        fishs = [Fish(name=i, price=i * 100) for i in range(1, 101)]
+        Fish.objects.bulk_create(fishs)
+        queryset = Fish.objects.all().order_by("id")
+        for list_per_page, current_page, expect_object_names in case:
+            pagination = Pagination(request, Fish, queryset, list_per_page)
+            pagination.page_num = current_page
+            objects = pagination.get_objects()
+            object_names = list(objects.values_list("name", flat=True))
+            self.assertEqual(object_names, expect_object_names)