How to get the original text of an AstNode? AbstractCstNode.text returns undefined

[rpedrosanto]

Hi,

I need to retrieve the original text of an AstNode from a successfully parsed langium document but when I use the text getter I always get undefined. The same is true for every other AbstractCstNode getter. What would be the correct way to get that text?

Thanks in advance, I appreciate it. Best.

[msujew]

Hey @rpedrosanto,

Using the text getter is supposed to be the correct way to get the text from a parsed document. Can you share a reproducible sample? It works for me as intended:

[rpedrosanto]

Can you share a reproducible sample?

Not sure I could do that easily enough, but I can see a difference in what you posted, the prototype for you is AbstractCstNode and what I get when I console log it is Object, maybe the way I'm bundling it with esbuild might be the problem.

[rpedrosanto]

It turns out that the problem is I have a web worker and I was losing the types during serialization when communicating with it.
Thanks for you attention @msujew !

[msujew]

I see, we used to have a similar issue. We addressed this by adding some more functionality to the JsonSerializer service. Take a look at the serializer options interface.

[luiz290788]

@msujew Do you have an example on how to do that? I was able to access node.$cstNode?._text but then I get a typescript error.

[msujew]

@luiz290788 What exactly are you trying to do? Can't you just use node.$cstNode?.text? _text is specifically not accessible.

Note that this question in particular was more related to serialization of AST nodes.

[luiz290788]

I have a command that returns the AST. I'm calling that command from the main thread of the browser. The command handler is getting the document and returning as the result of the command. When I get the returned value from the command node.$cstNode.text is not defined because it was lost in the serialization.

I was able to avoid the issue in my solution. I won't need to use the serializer, but it would be nice to learn about that. It also looks like that the serializer is not accessible from the command handler because it is not part of the shared services.

[msujew]

It also looks like that the serializer is not accessible from the command handler because it is not part of the shared services.

Right, but you can put the document.uri into the ServiceRegistry to find the serializer that belongs to the document that you're trying to serialize.