Question 1

How do I exclude certain models from the ERD diagram?

Accepted Answer

Rails Mermaid ERD doesn't currently support model exclusion via configuration. You might need to modify the gem's source code or pre-process your models manually to filter them out before generation.

Question 2

Can I customize the colors or styles of the generated diagram?

Accepted Answer

Customization is limited to what Mermaid supports, as the gem uses standard Mermaid ERD syntax. You can edit the generated HTML or Mermaid code directly, but there's no built-in styling configuration in the gem.

Question 3

Rails Mermaid ERD vs rails-erd: which should I use?

Accepted Answer

Rails Mermaid ERD generates portable, web-friendly HTML files with Mermaid, ideal for sharing and documentation. rails-erd produces Graphviz-based diagrams, offering more control over output formats but requiring Graphviz installation. Choose based on your need for portability versus customization.

Question 4

How to integrate this with GitHub Actions for automatic diagram updates?

Accepted Answer

Add a step in your GitHub Actions workflow to run the Rake task (e.g., 'bundle exec rails mermaid_erd') and commit or upload the generated HTML file. This automates diagram generation in CI, keeping documentation current.

Question 5

Does it handle polymorphic associations in ActiveRecord?

Accepted Answer

Yes, since it analyzes ActiveRecord models, it should include polymorphic associations in the diagram. However, the accuracy depends on how well ActiveRecord reflections are captured, and complex cases might not render perfectly.

Question 6

What happens if my app has hundreds of models?

Accepted Answer

For large schemas, the generated diagram can become cluttered and hard to read. The gem doesn't provide pagination or filtering, so you may need to rely on Mermaid's zoom features in the HTML or manually split the diagram.

rails-mermaid_erd

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