Structurizr: Cannot override styles when using default theme

[bdabelow]

Thanks a bunch for kroki, it makes my life a lot easier.

Small issue I have: this example fails with 0.21.0 and later, but works with 0.20.0:

workspace {

    model {
        user = person "User" "A user of my software system."
        softwareSystem = softwareSystem "Software System" "My software system."

        user -> softwareSystem "Uses"
    }

    views {
        theme default

        systemContext softwareSystem "SystemContext" {
            include *
            autoLayout
        }

        styles {
            element "Software System" {
                background #1168bd
                color #ffffff
            }
        }
    }
    
}

{
  "timestamp": "1687778933416",
  "level": "ERROR",
  "thread": "vert.x-eventloop-thread-1",
  "mdc": {
    "error_message": "OK",
    "path": "/structurizr/svg",
    "method": "POST",
    "action": "error",
    "error_code": "500",
    "failure_class_name": "java.lang.IllegalArgumentException",
    "user_agent": "curl/8.0.1"
  },
  "logger": "io.kroki.server.error.ErrorHandler",
  "message": "An error occurred",
  "context": "default",
  "exception": "
java.lang.IllegalArgumentException: An element style for the tag "Software System" already exists.
at com.structurizr.view.Styles.add(Styles.java:33)
at io.kroki.server.service.Structurizr.applyTheme(Structurizr.java:155)
at io.kroki.server.service.Structurizr.convert(Structurizr.java:113)
at io.kroki.server.service.Structurizr.convert(Structurizr.java:149)
at io.kroki.server.service.Structurizr.lambda$convert$0(Structurizr.java:80)
at io.vertx.core.impl.ContextBase.lambda$null$0(ContextBase.java:137)
at io.vertx.core.impl.ContextInternal.dispatch(ContextInternal.java:264)
at io.vertx.core.impl.ContextBase.lambda$executeBlocking$1(ContextBase.java:135)
at io.vertx.core.impl.TaskQueue.run(TaskQueue.java:76)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
at java.base/java.lang.Thread.run(Unknown Source)"
}

Stacktrace reformatted for better readability.

Error does not appear when either removing the theme default or the styles stanza.

Works a expected when loading theme via HTTP. Default theme URL as a workaround: https://raw.githubusercontent.com/structurizr/themes/2ee01b0dd917a77e6427f8cf870e976635fb07f9/default/theme.json

Probably related to #1543.

[ggrossetie]

@simonbrowndotje Hey Simon! I hope you are doing fine. What is the correct behavior here? I guess the style defined explicitly should have higher precedence and "override" the theme style? Is that correct? So should I catch IllegalArgumentException and ignore or check that "styles" class does not already have a style element define? Thanks!

[simonbrowndotje]

See https://structurizr.com/help/themes for more, but essentially any styles defined in the workspace will override any styles defined in the theme ... at least that's how I've implemented it. For example:

workspace {

    model {
        softwareSystem "Software System"
    }

    views {
        theme default

        systemLandscape "SystemLandscape" {
            include *
            autoLayout
        }

        styles {
            element "Software System" {
                background orange
            }
        }
    }
    
}

Generates this diagram:

The DSL parser checks for the existence of a style rather than catching IllegalArgumentException, and creates a new style if needed -> https://github.com/structurizr/dsl/blob/master/src/main/java/com/structurizr/dsl/ElementStyleParser.java#L30

[ggrossetie]

It makes sense, thanks for your reply! I will implement it that way 👍🏻