feat: Add Kiba::Extend::Job.output_fields method

Author: kspurgin

lib/kiba/extend/job.rb

@@ -6,6 +6,24 @@ module Extend
     module Job
       module_function
 
+      # @param jobkey [Symbol] registry entry for job with namespace
+      # @return [nil, Array<Symbol>] headers/fields for given job output
+      # @note Only works for CSV and JsonArray destinations. For JsonArray, only
+      #   returns the top-level fields of the objects/rows in the output.
+      def output_fields(jobkey)
+        return unless output?(jobkey)
+
+        entry = Kiba::Extend.registry.resolve(jobkey)
+        path = Pathname.new(entry.path)
+        dest = entry.dest_class.new(filename: path)
+        unless dest.respond_to?(:fields)
+          raise "No output field extraction logic exists for "\
+            "#{entry.dest_class}"
+        end
+
+        dest.fields
+      end
+
       # @param jobkey [Symbol] registry entry for job with namespace
       # @return [true] if output file already exists when run, or when running
       #   job results in 1 or more rows being written

spec/fixtures/output.json

@@ -0,0 +1 @@
+[{"Archival_Object__title":"Image of Bob and Sue","Archival_Object__dates":[{"Archival_Object__dates__begin":"1987","Archival_Object__dates__label":"other","Archival_Object__dates__date_type":"inclusive"},{"Archival_Object__dates__end":"1989","Archival_Object__dates__label":"other","Archival_Object__dates__date_type":"inclusive"}]},{"Archival_Object__title":"Audio recording of a horse","Archival_Object__subjects":["/Subjects/1","/Subjects/2"]}]

spec/helpers.rb

@@ -180,7 +180,7 @@ def populate_registry(more_entries: {})
           briefdescription]}
       },
       json_arr: {
-        path: fkeypath,
+        path: File.join(fixtures_dir, "output.json"),
         dest_class: Kiba::Extend::Destinations::JsonArray,
         creator: Helpers.method(:fake_creator_method)
       },

spec/kiba/extend/job_spec.rb

@@ -3,6 +3,63 @@
 require "spec_helper"
 
 RSpec.describe Kiba::Extend::Job do
+  describe ".output_fields" do
+    let(:result) { Kiba::Extend::Job.output_fields(key) }
+
+    context "when key not registered" do
+      let(:key) { :foo__bar }
+
+      it "returns nil" do
+        expect(result).to be_nil
+      end
+    end
+
+    context "when job has output" do
+      before(:context) do
+        Kiba::Extend.config.registry = Kiba::Extend::Registry::FileRegistry
+        prepare_registry
+      end
+      after(:context) { Kiba::Extend.reset_config }
+      let(:key) { :foo }
+
+      it "returns headers" do
+        expect(result).to eq(
+          [:objectnumber, :numberofobjects, :briefdescription,
+            :distinguishingfeatures, :comment]
+        )
+      end
+    end
+
+    context "when job has no output" do
+      before(:context) do
+        Kiba::Extend.config.registry = Kiba::Extend::Registry::FileRegistry
+        prepare_registry
+      end
+      after(:context) { Kiba::Extend.reset_config }
+      let(:key) { :noresultfile }
+
+      it "returns nil" do
+        expect(result).to be_nil
+      end
+    end
+
+    context "when job has JSON destination" do
+      before(:context) do
+        Kiba::Extend.config.registry = Kiba::Extend::Registry::FileRegistry
+        prepare_registry
+      end
+      after(:context) { Kiba::Extend.reset_config }
+      let(:key) { :json_arr }
+
+      it "returns top-level fields/keys" do
+        expect(result).to eq(
+          ["Archival_Object__title", "Archival_Object__dates",
+            "Archival_Object__subjects"]
+        )
+      end
+    end
+  end
+
   describe ".output?" do
     let(:result) { Kiba::Extend::Job.output?(key) }