How to add parameters for templates?

[Chiyo-no-sake]

I am working on an extension for CSS.
I need to create a new custom page for login, and I've done as shown in the v7 Documentation for new login methods.
I indeed succeeded in adding the new login entry that now shows up in the browser for the choice.
What I need to do now is to provide that HTML page with a parameter that is supplied via CLI arguments (for which I've already successfully created the YargsParser configuration and resolvers.).
From what I see, the values availables in template are either coming from the TemplateEngine (like it's done for baseUrl) or from the HtmlViewHandler (like for idpIndex).
There is only 1 HtmlViewHandler for all pages so I cannot create a custom handler that receives those variables from config. Also I think that it would be a bad idea to overwrite it for everyone, and same reasoning for the TemplateEngine.

Am I missing something easier to add this custom value to be injected in my template?

[joachimvh]

There is no immediate out-of-the-box solution for this. Your main two options seem to be to either add an additional component that is similar to the HtmlViewhandler, or a new EjsTemplateEngine.

HtmlViewHandler

Create a new class that extends the HtmlViewHandler, but have a new implementation of handle so it sends your additional parameter(s). Insert it in front of the other elements in the array here.

Specific Overrides can be used to determine the position of your new element in an existing array. See the documentation here or some info in the tutorial here.

The templates you then provide to your new class would be the ones that need those new parameters.

EjsTemplateEngine

Similar as above, but instead create a class similar to the EjsTemplateEngine that adds your new values, and then insert it in the list before the others here.

This would impact all resources that use the template engine, not just your new ones. But that seems like not that much of an issue.

[Chiyo-no-sake]

@joachimvh Thanks for the help, however while implementing I found out the the "overrideSteps" parameter is not accepted raising an "Invalid Predicate IRI: overrideSteps" error. Am I doing something wrong?

{
  "@context": [
    "https://linkedsoftwaredependencies.org/bundles/npm/@solid/community-server/^7.0.0/components/context.jsonld",
    "https://linkedsoftwaredependencies.org/bundles/npm/mypackage/^0.0.0/components/context.jsonld"
  ],
  "import": [
    "mypackage:config/handlers/html-view-handler.json"
  ],
  "@graph": [
    {
      "@type": "Override",
      "overrideInstance": {
        "@id": "urn:solid-server:default:InteractionHandler"
      },
      "overrideSteps": [
        {
          "@type": "OverrideListInsertBefore",
          "overrideParameter": {
            "@id": "InteractionHandler:_handlers"
          },
          "overrideTarget": {
            "@id": "urn:solid-server:default:HtmlViewHandler"
          },
          "overrideValue": {
            "@type": "MyPackageLoginViewHandler"
          }
        }
      ]
    }
  ]
}

[joachimvh]

Which version of Components.js are you using? This feature was added in v5.5.0.