How can I put a Postgres JSON value into a Rails fixture? - ruby-on-rails

Question

I just added a Postgres json type to a Rails/Active Record table I'm working with.
I'd like to populate a record with a default value in Rails fixtures:
fixture_id:
existing_column: "foobar"
newly_added_column: <%= JSON.dump({:reason => 'foobar'}) %>
Previously, I'd stored stringified JSON this way in a text column. However, when I now run this unit test:
test "my test" do
sut = fixtures(:fixture_id)
assert_not_nil sut.newly_added_column
end
The test fails. Because it is JSON at the database level, I don't think it's useful to dump it to a string, but the YAML fixtures can't seem to keep an object as a Hash (when I try it without the JSON.dump, I get ActiveRecord::Fixture::FormatError: a YAML error occurred parsing).
Mind you, I am using Rails 3, so I think some of the support for this may be in Rails 4, but in Rails 3, the migration to add a json Postgres column type still work.

Answer 1

I believe your fixture can be as simple as:
fixture_id:
existing_column: foobar
newly_added_column: {'reason':'foobar'}

Answer 2

To avoid having lengthy JSON structure inline in your fixtures, YAML provide a useful > operator
fixture_id:
existing_column: "foobar"
data: >
{
"can_edit": true,
"can_se": true,
"can_share": true,
"something_else": true
}

Answer 3

In Rails 5 it is possible to simply describe the JSON in YAML format. It will then be converted into correct JSON when fixtures are loaded in the DB:
parent:
name: A fixture
json_field:
- name: JSON Object 1
foo: bar
- name: JSON Object 2
foo: baz
(tested with JSONB attributes in Postgres)

Answer 4

If you are using ActiveRecord to generate content for your fixtures, you have to ensure that it converts attribute values to json. If you rely on the default serialization, it will produce hash rocket text which is invalid YAML.
For example, I have a legacy database that I am using to create fixtures for my new application (relevant code listed below):
presenter.rb
module FixturePresenter
def replacer(str)
str.downcase.tr(' ', '_').tr('-', '_')
end
# rubocop:disable Metrics/AbcSize
def plan
tag = replacer(name) + '_' + replacer(type)
<<~FIXTURE
#{tag}:
name: #{name}
type: #{type}
address: #{address}
FIXTURE
end
end
runner.rb
...
Legacy::Provider.all.each_with_index do |p, i|
p.extend(FixturePresenter)
f.puts p.plan
end
...
The address column in the plan table is a JSONB datatype. When we run this code this is the resulting YAML:
abc_plan_la_jolla:
name: ABC Plan La Jolla
type: default
address: {"street"=>"9888 Genesee Ave","unit"=>"","city"=>"La Jolla","state"=>"CA","postal_code"=>"92037"}
When you run your test you will get the very sad Syck error:
Psych::SyntaxError: (<unknown>): did not find expected ',' or '}' while parsing a flow mapping at line 4 column 12
The following change to the code will produce the correct YAML:
presenter.rb
address: #{address} to address: #{address.to_json}
The above change will produce a happy fixture definition:
abc_plan_la_jolla:
name: ABC Plan La Jolla
type: default
address: {"street":"9888 Genesee Ave","unit":"","city":"La Jolla","state":"CA","postal_code":"92037"}

Answer 5

Try
fixture_id:
existing_column: "foobar"
newly_added_column: "{\"reason\": \"foobar\"}"

Answer 6

I was maintaining a legacy Rails 4.2 application and needed to put JSON store value into a fixture. I made the following monkey patch to fix the problem. Hope this helps someone:
module ActiveRecord
class Fixture
def to_hash
h = fixture
model_class.attribute_names.each do |name|
typedef = model_class.type_for_attribute(name)
h[name] = typedef.coder.dump(h[name]) \
if typedef.is_a? ActiveRecord::Type::Serialized
end
h
end
end
end