FEATURE: Allow excluding uploads from min post length requirement (#31194)

Currently, the markdown for uploads is counted towards post minimum length requirements. This change introduces a site setting `prevent_uploads_only_posts` which can be flipped to exclude upload segments from the calculation.

config/locales/server.en.yml

@@ -1743,6 +1743,7 @@ en:
     support_mixed_text_direction: "Support mixed left-to-right and right-to-left text directions"
     min_post_length: "Minimum allowed post length in characters (excluding personal messages)"
     min_first_post_length: "Minimum allowed first post (topic body) length (excluding personal messages)"
+    prevent_uploads_only_posts: "Don't count upload markdown code when checking for min post length"
     min_personal_message_post_length: "Minimum allowed post length in characters for messages (both first post and replies)"
     max_post_length: "Maximum allowed post length in characters"
     topic_featured_link_enabled: "Allows users to associate a feature link with their topics. When turned on, topics can have a highlighted link attached, which is publicly visible and can be edited if the user has sufficient permissions. The feature link can enhance a topic's comprehensibility by providing related additional content."

config/site_settings.yml

@@ -916,6 +916,9 @@ posting:
       ja: 8
       zh_CN: 8
       zh_TW: 8
+  prevent_uploads_only_posts:
+    client: true
+    default: false
   min_personal_message_post_length:
     client: true
     min: 1

lib/validators/post_validator.rb

@@ -48,7 +48,13 @@ class PostValidator < ActiveModel::Validator
         SiteSetting.post_length
       end
 
-    StrippedLengthValidator.validate(post, :raw, post.raw, range)
+    StrippedLengthValidator.validate(
+      post,
+      :raw,
+      post.raw,
+      range,
+      strip_uploads: SiteSetting.prevent_uploads_only_posts,
+    )
   end
 
   def max_posts_validator(post)

lib/validators/stripped_length_validator.rb

@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 class StrippedLengthValidator < ActiveModel::EachValidator
-  def self.validate(record, attribute, value, range)
+  def self.validate(record, attribute, value, range, strip_uploads: false)
     if value.blank?
       record.errors.add attribute, I18n.t("errors.messages.blank")
     elsif value.length > range.end
@@ -12,7 +12,7 @@ class StrippedLengthValidator < ActiveModel::EachValidator
                           length: value.length,
                         )
     else
-      value = get_sanitized_value(value)
+      value = get_sanitized_value(value, strip_uploads:)
 
       if value.length < range.begin
         record.errors.add attribute, I18n.t("errors.messages.too_short", count: range.begin)
@@ -26,12 +26,14 @@ class StrippedLengthValidator < ActiveModel::EachValidator
     self.class.validate(record, attribute, value, range)
   end
 
-  def self.get_sanitized_value(value)
+  def self.get_sanitized_value(value, strip_uploads: false)
     value = value.dup
     value.gsub!(/<!--(.*?)-->/, "") # strip HTML comments
     value.gsub!(/:\w+(:\w+)?:/, "X") # replace emojis with a single character
     value.gsub!(/\.{2,}/, "…") # replace multiple ... with …
     value.gsub!(/\,{2,}/, ",") # replace multiple ,,, with ,
+    value.gsub!(/!\[.*\]\(.+\)/, "") if strip_uploads
+
     value.strip
   end
 end

spec/lib/validators/post_validator_spec.rb

@@ -46,7 +46,7 @@ RSpec.describe PostValidator do
     end
   end
 
-  describe "stripped_length" do
+  describe "#stripped_length" do
     it "adds an error for short raw" do
       post.raw = "abc"
       validator.stripped_length(post)
@@ -103,6 +103,26 @@ RSpec.describe PostValidator do
       validator.stripped_length(post)
       expect(post.errors.count).to eq(1)
     end
+
+    context "when configured to count uploads" do
+      before { SiteSetting.prevent_uploads_only_posts = false }
+
+      it "counts image tags" do
+        post.raw = "![A cute cat|690x472](upload://3NvZqZ2iBHjDjwNVI4QyZpkaC5r.png)"
+        validator.stripped_length(post)
+        expect(post.errors.count).to eq(0)
+      end
+    end
+
+    context "when configured to not count uploads" do
+      before { SiteSetting.prevent_uploads_only_posts = true }
+
+      it "doesn't count image tags" do
+        post.raw = "![A cute cat|690x472](upload://3NvZqZ2iBHjDjwNVI4QyZpkaC5r.png)"
+        validator.stripped_length(post)
+        expect(post.errors.count).to eq(1)
+      end
+    end
   end
 
   describe "max_posts_validator" do