Xtext assign object in xtext file - eclipse

Question

Trying to make a meta model for Mongoose and MondoDb, using metamodeling concepts, eclipse and xtext.
I am trying to assign object that i created in my test.mydsl file to another object in the same file, but i get error in my test.mydsl file.
I am trying to assign created Schema(sc1) object to Collection(col) object, but currently getting an error
error message
the feature 'validate' of
'paket.impl.NCollectionImpl#67d76e14{platform:/resource/test/classes/test.mydsl#//#collections.0}'
contains an unresolved proxy
'paket.impl.SchemaImpl#361d8284{platform:/resource/test/classes/test.mydsl#|0}'
my grammar for Schema and Collection
Schema returns Schema:
{Schema}
('Schema' '<' Name=EString) '>'
'{'
(schemaExpression+=Expression ( "," schemaExpression+=Expression)*)?
(verificationDocumentElement+=VerDocElement ( "," verificationDocumentElement+=VerDocElement)*)?
'}';
NCollection returns NCollection:
{NCollection}
('Collection' '<' Name=EString) ',' (validate=[Schema|EString])? '>'
'{'
(document+=Document ( "," document+=Document)*)?
'}';
my test.mydsl
Database<db1>{
Schema<sc1>{
var ja=lp
ime:{
type:String,
min:123.0
}
}
Collection<col, sc1>
{
}
}
I tried all, but unsuccessful.
Any ideas what to do?
Thanks
EDIT:
Maybe I was not clear enough. The major problem is with "validate" attribute in NCollection rule.
When I create my Schema object(sc1 in test.mydsl) and then try to pass it to Collection(col in test.mydsl) as a "sc1", the "validate" attribute cannot accept it like string, and I don't know how to pass it like Schema object.
I hope this explanation helps.

Answer 1

Please try to use name=EStringinstead of Name=EString as Xtext imposes a special default semantics for the attribute name. Also I recommend to look into the documentation.

Answer 2

The code
validate=[Schema|EString]
says: I want a schema reference via a String, i.e. "sc1" instead of the name. Xtext doesn't know how to convert a string into a reference. Use this instead:
validate=[Schema]
which is short for
validate=[Schema|ID]
That will use the name of the Schema as reference. Note that you have to write
('Schema' '<' name=EString) '>'
i.e. lower case name to make it work. Xtext has special handling for properties called name.