Add a `Blob` model that wraps `Gitlab::Git::Blob`rs-blob

This allows us to take advantage of Rails' `to_partial_path` to render
the correct partial based on the Blob type, rather than cluttering the
view with conditionals.

It also allows (and will allow in the future) better encapsulation for
Blob-related logic which makes sense for our Rails app but might not
make as much sense for the core `gitlab_git` library, such as detecting
if the blob is an SVG.

1 files changed, 34 insertions, 0 deletions

diff --git a/app/models/blob.rb b/app/models/blob.rb
new file mode 100644
index 00000000000..8ee9f3006b2
--- /dev/null
+++ b/app/models/blob.rb
@@ -0,0 +1,34 @@
+# Blob is a Rails-specific wrapper around Gitlab::Git::Blob objects
+class Blob < SimpleDelegator
+  # Wrap a Gitlab::Git::Blob object, or return nil when given nil
+  #
+  # This method prevents the decorated object from evaluating to "truthy" when
+  # given a nil value. For example:
+  #
+  #     blob = Blob.new(nil)
+  #     puts "truthy" if blob # => "truthy"
+  #
+  #     blob = Blob.decorate(nil)
+  #     puts "truthy" if blob # No output
+  def self.decorate(blob)
+    return if blob.nil?
+
+    new(blob)
+  end
+
+  def svg?
+    text? && language && language.name == 'SVG'
+  end
+
+  def to_partial_path
+    if lfs_pointer?
+      'download'
+    elsif image? || svg?
+      'image'
+    elsif text?
+      'text'
+    else
+      'download'
+    end
+  end
+end