VSCode CALM Extension: Fixing Mermaid Render Errors

by Alex Johnson 52 views

Bug Report: Mermaid Reserved Words Causing Render Failures

Having trouble rendering your CALM models in VSCode? You're not alone! A pesky bug in the CALM VSCode extension is preventing models from rendering correctly when node IDs contain words reserved by Mermaid. Let's dive into the details and see how this impacts your architecture-as-code workflow.

Understanding the Issue

The core problem lies in how the VSCode extension handles node IDs when generating Mermaid diagrams. Mermaid, a popular diagramming tool, has certain reserved words that have special meanings. When these words appear in node IDs within your CALM models, Mermaid's parser gets confused and throws an error, preventing the diagram from rendering.

This issue arises because the Handlebars templates, which are responsible for converting your CALM models into Mermaid syntax, don't account for these reserved words. They directly use the node IDs without checking for conflicts, leading to invalid Mermaid code.

Steps to Reproduce

Want to see the bug in action? Here’s how you can reproduce the error:

  1. Create a CALM architecture JSON file: Design a CALM architecture JSON file with a node that boasts a unique ID encompassing a Mermaid reserved word. Examples include end-user, graph-api, or subgraph-service.
  2. Open the CALM file in VSCode: Fire up VSCode and open the CALM file, ensuring the CALM extension is installed and ready to roll.
  3. View the architecture preview panel: Take a peek at the architecture preview panel to witness the rendering magic (or, in this case, the rendering failure).

Expected vs. Actual Results

Expected Result: You anticipate a beautifully rendered architecture diagram, showcasing all nodes, including those with reserved words in their IDs. The node with the unique ID end-user should be displayed as a properly formatted Mermaid node with its label proudly presented.

Actual Result: Instead, you're greeted with a parse error, similar to this:

Parse error on line X:
...end-user["End User"]:::actor
---
Expecting 'SEMI', 'NEWLINE', 'EOF', 'AMP', 'START_LINK', 'LINK', got 'end'

The preview panel throws an error, and your diagram remains stubbornly unrendered. This is because Mermaid's parser mistakenly interprets reserved words like end, graph, and subgraph as syntax keywords, even when they're part of hyphenated node IDs. The parser stumbles upon end in end-user before recognizing the hyphen, leading to the parsing failure.

Impact

This bug affects any CALM model where node unique IDs contain Mermaid reserved words, including:

  • Complete IDs: end, graph, subgraph
  • Word boundaries: end-user, my-end-service, graph-api, service-end

Environment Details

Here's the environment where this bug has been observed:

  • Project: CALM VSCode Extension v0.0.8
  • Package: calm-widgets v1.0.0
  • VSCode: 1.95.x
  • OS: macOS 14.x
  • Node: v20.x

List of Mermaid Reserved Words

Here's a list of Mermaid reserved words that trigger this issue:

graph, subgraph, end, click, call, class, classDef, style, linkStyle, direction, TB, BT, RL, LR, TD, BR

Important Note

Interestingly, IDs where the reserved word is embedded within a larger word (e.g., endpoint, backend, graphql) do NOT cause issues and render correctly. It's the isolated reserved words or those at word boundaries that create the problem.

Diving Deeper: Why This Happens

The heart of the problem resides in the Handlebars templates used to generate Mermaid syntax. These templates directly employ node IDs without validating for reserved word conflicts, ultimately resulting in invalid Mermaid syntax. This direct usage without validation is where the bug originates.

How to Solve the problem:

To resolve this issue, the Handlebars templates must be updated to properly escape or transform node IDs that contain Mermaid reserved words. This could involve:

  • Adding a prefix or suffix to the node ID
  • Replacing the reserved word with an alternative
  • Using a more robust escaping mechanism provided by Mermaid

By implementing one of these solutions, the VSCode extension can avoid generating invalid Mermaid syntax and ensure that CALM models render correctly, even when node IDs contain reserved words.

Potential Solutions and Workarounds

While a permanent fix is in the works, here are some potential workarounds you can use to sidestep this issue:

  1. Rename Node IDs: The simplest workaround is to rename any node IDs that contain Mermaid reserved words. For example, instead of end-user, you could use user-end or final-user. While this might require some adjustments to your CALM models, it's a quick and effective way to avoid the rendering error.
  2. Use Alternative Diagramming Tools: If you're not strictly tied to Mermaid, consider using alternative diagramming tools that don't have the same reserved word conflicts. There are many online tools and VSCode extensions that can render your CALM models without encountering this issue.
  3. Escaping Reserved Words: Another approach is to manually escape the reserved words within your node IDs. Mermaid might offer a mechanism for escaping special characters or reserved words. Research Mermaid's documentation to see if there's a way to escape these words in your node IDs.

Community and Collaboration

It's crucial to report such bugs to the developers of the CALM VSCode extension. Reporting bugs helps them identify and address issues, ultimately improving the extension for everyone.

Furthermore, engaging with the community can provide valuable insights and alternative solutions. Share your experiences and workarounds with other CALM users. Collaboration can lead to faster resolutions and a more robust ecosystem.

Conclusion: A Temporary Hiccup in the Architecture-as-Code Journey

While this bug is certainly a nuisance, it's important to remember that it's a temporary setback in the broader journey of architecture-as-code. The CALM VSCode extension is a valuable tool for visualizing and managing your system architectures, and this issue doesn't diminish its overall potential.

By understanding the root cause of the problem, implementing the suggested workarounds, and engaging with the community, you can continue to leverage the power of CALM and architecture-as-code, even with this bug in the mix.

Stay tuned for updates and fixes from the CALM VSCode extension developers. In the meantime, keep building, keep innovating, and keep those architectures rendering (as best as you can!).

For more information on Mermaid syntax and reserved words, refer to the official Mermaid Documentation.