XTEXT中MongoDb示例无法解析类型问题求助

Hey there! Let's dig into that type resolution issue you're hitting with your Xtext/MongoDB DSL. I’ve tangled with Xtext’s finicky type scoping before, so let’s break this down step by step.

First, let’s start with the basics: Are your types properly defined? #

From the snippet you shared, your MongoBean definition cuts off at name=ValidID ...—so first, make sure Album and Track are explicitly declared as MongoBeans in your grammar. For example:

MongoBean:
    name=ValidID '{'
        features+=Feature*
    '}';

Feature:
    (type=JvmTypeReference name=ValidID) // Uses Xbase's type reference system
    | ...; // Add other feature types if needed

If Album and Track are separate MongoBean definitions (like Artist), they need to exist in your DSL either in the same package or be imported properly.

Next, check your imports and package structure #

Xtext relies on proper scoping and imports to resolve types, just like Java.

• If Album/Track are in the same package as Artist, make sure they’re nested under the same package declaration:

  package com.yourproject.mongo {
      MongoBean Artist {
          Album[] studioAlbums
          Track topTrack
      }
      MongoBean Album { ... }
      MongoBean Track { ... }
  }
  

• If they’re in a different package, add an import section at the top of your DSL file:

  import com.yourproject.mongo.Album
  import com.yourproject.mongo.Track
  
  package com.yourproject.mongo {
      MongoBean Artist { ... }
  }
  

Verify Xbase integration is set up correctly #

Since your grammar inherits from Xbase, you need to ensure your MongoBeans are mapped to valid JVM types (so the IDE recognizes them as resolvable types). Here’s what to check:

1. JVM Model Inferrer: You need an inferrer that converts your MongoBean definitions into Java classes. In your MongoBeansJvmModelInferrer.xtend (generated with your Xtext project), make sure it’s generating JVM types for each MongoBean:

   class MongoBeansJvmModelInferrer extends AbstractModelInferrer {
       @Inject extension IJvmTypesBuilder
   
       def void infer(MongoBean bean, IJvmDeclaredTypeAcceptor acceptor, boolean isPreIndexingPhase) {
           acceptor.accept(bean.toClass(bean.fullyQualifiedName)) [
               // Add fields, constructors, or methods here as needed
               for (feature : bean.features) {
                   if (feature instanceof FeatureWithType) {
                       members += feature.toField(feature.name, feature.type)
                   }
               }
           ]
       }
   }
   

2. Runtime Module Binding: Ensure your runtime module binds the inferrer correctly:

   public class MongoBeansRuntimeModule extends AbstractMongoBeansRuntimeModule {
       @Override
       public Class<? extends IJvmModelInferrer> bindIJvmModelInferrer() {
           return MongoBeansJvmModelInferrer.class;
       }
   }
   

Fix IDE caching issues #

Xtext’s IDE can sometimes hold onto stale cache data, causing false "cannot resolve type" errors. Try these quick fixes:

• Right-click your project → Run As → Xtext Generate Artifacts to regenerate grammar-related code
• Go to Project → Clean... and rebuild your project
• Close and re-open your IDE (annoying, but often fixes cache glitches)

Double-check type references in your DSL #

Make sure you’re using valid Xbase-compatible type syntax in your Artist definition. For example:

MongoBean Artist {
    List<Album> albums // Uses Xbase's generic type syntax
    Track favoriteTrack
}

Avoid typos in type names—even a single wrong character will trigger the resolution error.

内容的提问来源于stack exchange，提问作者Marko Radosavljevic