Adds basic support for queries generated by #find_by_sql

Relates to #32

Allows exporting data that was generated by [find_by_sql][]. This can be desirable when the caller is required to export a calculated field that is not stored directly on the table as demonstrated below.

```ruby
User.find_by_sql("SELECT id, 'custom_value' AS custom_field FROM users")
ArtVandelay::Export.new(export).csv
```

As such, this feature does not support the `in_batches_of` option, since
that would be the responsibility of the query.

This feature also does not (yet) support the `attributes` option.

[find_by_sql]: https://api.rubyonrails.org/classes/ActiveRecord/Querying.html#method-i-find_by_sql

lib/art_vandelay.rb

@@ -40,6 +40,8 @@ def csv
  end
  elsif records.is_a?(ActiveRecord::Base)
  csv_exports << CSV.parse(generate_csv(records), headers: true)
+ elsif records.is_a?(Array)
+ csv_exports << CSV.parse(generate_csv(records), headers: true)
  end
 
  Result.new(csv_exports)
@@ -88,7 +90,7 @@ def filtered_values(attributes)
  def generate_csv(relation)
  CSV.generate do |csv|
  csv << header
- if relation.is_a?(ActiveRecord::Relation)
+ if relation.is_a?(ActiveRecord::Relation) || relation.is_a?(Array)
  relation.each do |record|
  csv << row(record.attributes)
  end
@@ -104,7 +106,12 @@ def header
  standardized_attributes.include?(column_name)
  end
  else
- model.attribute_names
+ case records
+ when ActiveRecord::Relation, ActiveRecord::Base
+ model.attribute_names
+ when Array
+ records.first.attributes.keys
+ end
  end
  end
 
@@ -113,7 +120,12 @@ def model
  end
 
  def model_name
- records.model_name.name
+ case records
+ when ActiveRecord::Relation, ActiveRecord::Base
+ records.model_name.name
+ when Array
+ records.first.model_name.name
+ end
  end
 
  def row(attributes)

test/art_vandelay_test.rb

@@ -72,6 +72,26 @@ class Export < ArtVandelayTest
  )
  end
 
+ test "it creates a CSV when passed an Array of ActiveRecord instances" do
+ user = User.create!(email: "[email protected]", password: "password")
+ export = User.find_by_sql("SELECT id, 'custom_value' AS custom_field FROM users")
+
+ result = ArtVandelay::Export.new(export).csv
+ csv = result.csv_exports.first
+
+ assert_equal(
+ [
+ ["id", "custom_field"],
+ [user.id.to_s, "custom_value"]
+ ],
+ csv.to_a
+ )
+ assert_equal(
+ ["id", "custom_field"],
+ csv.headers
+ )
+ end
+
  test "it controlls what data is filtered" do
  user = User.create!(email: "[email protected]", password: "password")
  ArtVandelay.setup do |config|