Update a model from inside a command handler

[luiz290788]

Is there any way to update a document from inside of a command handler? Do I need to trigger another command?

[msujew]

Hey @luiz290788,

what exactly are you trying to accomplish? In what ways are you looking to update the document? Do you want to trigger a code action programmatically, so that the editor value is actually changed? Or is it enough to just update the document internally in Langium?

[luiz290788]

That's what we are doing right now, but we were wondering if we need to send the generated content back to the ui thread. Is there any way that we can set the value of the document from inside of the language server?

[msujew]

You could always just generate a document from the string directly via LangiumDocumentFactory#fromString, but then the user won't be able to see the document. Language servers work in a master-slave architecture, where the editor has complete control over the text document and only consults the language server for certain requests. The editor will never ask the server what the state of the document is, it will only push changes to the server.

[luiz290788]

I see, so the best way is to send the generated content back to the main thread and let the editor save the content.

[msujew]

I think so. Langium's document representation is completely internalized and isolated from "the real world". There's no way to just modify the document and have the changes reflected anywhere else, since they're decoupled.