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.

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