Fix missing headers when exporting Project data

Project::Export uses the first request in the project to generate the
CSV headers. However, if the request hasn't had data extracted, the
headers for the dataset columns will be blank, even though other
requests in the project may have had a dataset extraction.

This commit ensures that headers are always present by looking up the
project's key set, and iterating through that to fetch the relevant
submission value for that key, or otherwise assigning a nil value.

This has the benefit of ensuring that the keys/values exported are
always in sync with the current project key set.

Fixes #8141.

app/models/project/export/info_request.rb

@@ -24,7 +24,7 @@ def data
       latest_status_contributor: status_contributor,
       status: described_state,
       dataset_contributor: dataset_contributor
-    }.merge(extracted_values_as_hash)
+    }.merge(dataset_values)
   end
 
   private
@@ -53,6 +53,12 @@ def dataset_contributor
     extraction_submission.user.name
   end
 
+  def dataset_values
+    project.key_set.keys.pluck(:title).each_with_object({}) do |key, memo|
+      memo[key] = extracted_values_as_hash[key]
+    end
+  end
+
   def extracted_values
     return unless extraction_submission
 

doc/CHANGES.md

@@ -2,6 +2,7 @@
 
 ## Highlighted Features
 
+* Fix missing headers when exporting Project data (Gareth Rees)
 * Reduce amount of storage related background jobs (Graeme Porteous)
 * Add automatic parsing of emails contain Excel spreadsheets (Graeme Porteous)
 * Improve rendering of admin hidden request prominence and explanations (Graeme

spec/models/project/export/info_request_spec.rb

@@ -6,6 +6,10 @@
   include LinkToHelper
 
   let(:project) { FactoryBot.build(:project) }
+
+  let(:key_set) { FactoryBot.build(:dataset_key_set, resource: project) }
+  let!(:dataset_key) { FactoryBot.create(:dataset_key, key_set: key_set) }
+
   let(:contributor) { FactoryBot.build(:user) }
 
   let(:public_body) { FactoryBot.build(:public_body) }
@@ -71,7 +75,8 @@
           request_owner: info_request.user.name,
           latest_status_contributor: contributor.name,
           status: info_request.described_state,
-          dataset_contributor: nil
+          :dataset_contributor => nil,
+          'Were there any errors?' => nil
         )
       end
     end