---
title: "Set model name in fixtures as metadata"
description:
  "In Rails 5 model name can be set as metadata in the fixture file, rather than
  being infered from the fixture filename."
canonical_url: "https://www.bigbinary.com/blog/set-model-name-in-fixtures-as-metadata"
markdown_url: "https://www.bigbinary.com/blog/set-model-name-in-fixtures-as-metadata.md"
---

# Set model name in fixtures as metadata

In Rails 5 model name can be set as metadata in the fixture file, rather than
being infered from the fixture filename.

- Author: Srihari K
- Published: August 9, 2016
- Categories: Rails 5, Rails

## Fixtures

In Rails, for setting up test data we use fixtures. Fixtures are written as YAML
files placed in `test/fixtures` directory in the Rails app.

The model name of a fixture is automatically picked up from the fixture file
name.

Generally in Rails, the model name and table name follow a strict convention.
The table for `User` model will be `users`. By this convention, the fixture file
for `User` model is `test/fixtures/users.yml`.

But sometimes model names do not match directly with the table name. When we are
building on top of a legacy application or we have namespacing of models, we
might run into this scenario. In such cases detection of model name from fixture
file name becomes difficult.

When automatic detection of model name from fixture file name fails, we can
specify the table name using the
[set_fixture_class](http://api.rubyonrails.org/classes/ActiveRecord/TestFixtures/ClassMethods.html#method-i-set_fixture_class)
method. Take a look at our older
[blog](tricks-and-tips-for-using-fixtures-in-rails) for an example of how to do
this.

One drawback of using this approach is that, the model name set using
`set_fixture_class` is available only in the context of tests. When we run
`rake db:fixtures:load` to load the fixtures, the tests are not run, and the
fixture file is not associated with the model name we set using
`set_fixture_class`. This will cause failure to load the fixtures correctly.

## The Rails 5 way

In Rails 5 a new key is [added](https://github.com/rails/rails/pull/20574) to
specify the model name for a fixture file.

Let us consider the example where our table was named `morning_appts`, and we
used a more appropriately named model `MorningAppointment` to represent this
table.

We can now set the table name in our fixture file
`test/fixtures/morning_appts.yml` as follows :

```yaml
_fixture:
  model_class: MorningAppointment
standup:
  name: Standup
  priority: 1
```

The special key `_fixture` in the fixture file is now used to store metadata
about the fixture. `model_class` is the key we can use to specify the model name
for the fixture.

We can now use this fixture to load test data using the rake task
`rake db:fixtures:load` as well.

Happy Testing!

## Links

- [Human page](https://www.bigbinary.com/blog/set-model-name-in-fixtures-as-metadata)