Enable Tag Merging

CHANGELOG.rst

@@ -8,6 +8,7 @@ Changelog
   The previous behavior for this was that by default tag items were not ordered. In practice tag items often end up ordered by creation date anyways, just due to how databases work, but this was not a guarantee.
   If you wish to have the old behavior, set ``ordering=[]`` to your ``TaggableManager`` instance.
   We believe that this should not cause a noticable performance change, and the number of queries involved should not change.
+* Added the ability to merge tags via the admin
 * Add Django 5.0 support (no code changes were needed, but now we test this release).
 * Add Python 3.12 support
 

docs/admin.rst

@@ -39,3 +39,18 @@ method to the :class:`~django.contrib.admin.ModelAdmin`, using
 
         def tag_list(self, obj):
             return u", ".join(o.name for o in obj.tags.all())
+
+
+Merging tags in the admin
+~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Functionality has been added to the admin app to allow for tag "merging". Multiple tags can be selected, and all of their usages will be replaced by the tag that you choose to use.
+
+To merge your tags follow these steps:
+
+1. Navigate to the Tags page inside of the Taggit app
+2. Select the tags that you want to merge
+3. Use the dropdown action list and select `Merge selected tags` and then click `Go`
+4. This will redirect you onto a new page where you can insert the new tag name.
+5. Click `Merge Tags`
+6. This will redirect you back to the tag list

taggit/admin.py

@@ -1,7 +1,12 @@
 from django.contrib import admin
+from django.db import transaction
+from django.shortcuts import redirect, render
+from django.urls import path
 
 from taggit.models import Tag, TaggedItem
 
+from .forms import MergeTagsForm
+
 
 class TaggedItemInline(admin.StackedInline):
     model = TaggedItem
@@ -14,3 +19,68 @@ class TagAdmin(admin.ModelAdmin):
     ordering = ["name", "slug"]
     search_fields = ["name"]
     prepopulated_fields = {"slug": ["name"]}
+    actions = ["render_tag_form"]
+
+    def get_urls(self):
+        urls = super().get_urls()
+        custom_urls = [
+            path(
+                "merge-tags/",
+                self.admin_site.admin_view(self.merge_tags_view),
+                name="taggit_tag_merge_tags",
+            ),
+        ]
+        return custom_urls + urls
+
+    @admin.action(description="Merge selected tags")
+    def render_tag_form(self, request, queryset):
+        selected = request.POST.getlist(admin.helpers.ACTION_CHECKBOX_NAME)
+        if not selected:
+            self.message_user(request, "Please select at least one tag.")
+            return redirect(request.get_full_path())
+
+        selected_tag_ids = ",".join(selected)
+        redirect_url = f"{request.get_full_path()}merge-tags/"
+
+        request.session["selected_tag_ids"] = selected_tag_ids
+
+        return redirect(redirect_url)
+
+    def merge_tags_view(self, request):
+        selected_tag_ids = request.session.get("selected_tag_ids", "").split(",")
+        if request.method == "POST":
+            form = MergeTagsForm(request.POST)
+            if form.is_valid():
+                new_tag_name = form.cleaned_data["new_tag_name"]
+                new_tag, created = Tag.objects.get_or_create(name=new_tag_name)
+                with transaction.atomic():
+                    for tag_id in selected_tag_ids:
+                        tag = Tag.objects.get(id=tag_id)
+                        tagged_items = TaggedItem.objects.filter(tag=tag)
+                        for tagged_item in tagged_items:
+                            if TaggedItem.objects.filter(
+                                tag=new_tag,
+                                content_type=tagged_item.content_type,
+                                object_id=tagged_item.object_id,
+                            ).exists():
+                                # we have the new tag as well, so we can just
+                                # remove the tag association
+                                tagged_item.delete()
+                            else:
+                                # point this taggedItem to the new one
+                                tagged_item.tag = new_tag
+                                tagged_item.save()
+
+                self.message_user(request, "Tags have been merged", level="success")
+                # clear the selected_tag_ids from session after merge is complete
+                request.session.pop("selected_tag_ids", None)
+
+                return redirect("..")
+            else:
+                self.message_user(request, "Form is invalid.", level="error")
+
+        context = {
+            "form": MergeTagsForm(),
+            "selected_tag_ids": selected_tag_ids,
+        }
+        return render(request, "admin/taggit/merge_tags_form.html", context)

taggit/forms.py

@@ -52,3 +52,12 @@ def has_changed(self, initial_value, data_value):
         initial_value.sort()
 
         return initial_value != data_value
+
+
+class MergeTagsForm(forms.Form):
+    new_tag_name = forms.CharField(
+        label="New Tag Name",
+        max_length=100,
+        widget=forms.TextInput(attrs={"id": "id_new_tag_name"}),
+        help_text="Enter new or existing tag name",
+    )

taggit/templates/admin/taggit/merge_tags_form.html

@@ -0,0 +1,31 @@
+{% extends "admin/base.html" %} {% block content %}
+<div id="mergeTagsModal">
+  <div>
+    <div>
+      <div>
+        <form
+          id="merge-tags-form"
+          method="post"
+          action="{% url 'admin:taggit_tag_merge_tags' %}"
+        >
+          {% csrf_token %} {% for field in form %}
+          <div>
+            {{ field.label_tag }} {{ field }} {% if field.errors %}
+            <ul class="errorlist">
+              {% for error in field.errors %}
+              <li>{{ error }}</li>
+              {% endfor %}
+            </ul>
+            {% endif %}
+          </div>
+          {% endfor %}
+          <p><i><strong>Enter new or existing tag name</strong></strong></i></p>
+          <div>
+            <input type="submit" class="btn btn-primary"></input>
+          </div>
+        </form>
+      </div>
+    </div>
+  </div>
+</div>
+{% endblock %}

tests/test_admin.py

@@ -2,6 +2,8 @@
 from django.test import TestCase
 from django.urls import reverse
 
+from taggit.models import Tag
+
 from .models import Food
 
 
@@ -10,6 +12,11 @@ def setUp(self):
         super().setUp()
         self.apple = Food.objects.create(name="apple")
         self.apple.tags.add("Red", "red")
+        self.pear = Food.objects.create(name="pear")
+        self.pear.tags.add("red", "RED")
+        self.peach = Food.objects.create(name="peach")
+        self.peach.tags.add("red", "Yellow")
+
         user = User.objects.create_superuser(
             username="admin", email="[email protected]", password="password"
         )
@@ -40,3 +47,33 @@ def test_get_change(self):
             reverse("admin:tests_food_change", args=(self.apple.pk,))
         )
         self.assertEqual(response.status_code, 200)
+
+    def test_tag_merging(self):
+        response = self.client.get(reverse("admin:taggit_tag_changelist"))
+
+        # merging red and RED into Red
+        pks_to_select = [Tag.objects.get(name="red").pk, Tag.objects.get(name="RED").pk]
+        response = self.client.post(
+            reverse("admin:taggit_tag_changelist"),
+            data={"action": "render_tag_form", "_selected_action": pks_to_select},
+        )
+        # we're redirecting
+        self.assertEqual(response.status_code, 302)
+        # make sure what we expected got into the session keys
+        assert "selected_tag_ids" in self.client.session.keys()
+        self.assertEqual(
+            self.client.session["selected_tag_ids"], ",".join(map(str, pks_to_select))
+        )
+
+        # let's do the actual merge operation
+        response = self.client.post(
+            reverse("admin:taggit_tag_merge_tags"), {"new_tag_name": "Red"}
+        )
+        self.assertEqual(response.status_code, 302)
+
+        # time to check the result of the merges
+        self.assertSetEqual({tag.name for tag in self.apple.tags.all()}, {"Red"})
+        self.assertSetEqual({tag.name for tag in self.pear.tags.all()}, {"Red"})
+        self.assertSetEqual(
+            {tag.name for tag in self.peach.tags.all()}, {"Yellow", "Red"}
+        )