Include YAML files from snakeyaml -

i have yaml files include, similar question, snakeyaml: how can include yaml file inside another?

for example:

%yaml 1.2 --- !include "load.yml"  !include "load2.yml" 

i having lot of trouble it. have constructor defined, , can make import 1 document, not two. error is:

exception in thread "main" expected '<document start>', found tag  in 'reader', line 5, column 1:     !include "load2.yml"     ^ 

with 1 include, snakeyaml happy finds eof , processes import. two, it's not happy (above).

my java source is:

package yaml; import java.io.file; import java.io.fileinputstream; import java.io.filenotfoundexception; import java.io.inputstream;  import org.yaml.snakeyaml.yaml; import org.yaml.snakeyaml.constructor.abstractconstruct; import org.yaml.snakeyaml.constructor.constructor; import org.yaml.snakeyaml.nodes.node; import org.yaml.snakeyaml.nodes.scalarnode; import org.yaml.snakeyaml.nodes.tag;  public class main {     final static constructor constructor = new myconstructor();      private static class importconstruct extends abstractconstruct {         @override         public object construct(node node) {             if (!(node instanceof scalarnode)) {                 throw new illegalargumentexception("non-scalar !import: " + node.tostring());             }              final scalarnode scalarnode = (scalarnode)node;             final string value = scalarnode.getvalue();              file file = new file("src/imports/" + value);             if (!file.exists()) {                 return null;             }              try {                 final inputstream input = new fileinputstream(new file("src/imports/" + value));                 final yaml yaml = new yaml(constructor);                 return yaml.loadall(input);             } catch (filenotfoundexception ex) {                 ex.printstacktrace();             }             return null;         }     }      private static class myconstructor extends constructor {         public myconstructor() {             yamlconstructors.put(new tag("!include"), new importconstruct());         }     }      public static void main(string[] args) {         try {             final inputstream input = new fileinputstream(new file("src/imports/example.yml"));             final yaml yaml = new yaml(constructor);             object object = yaml.load(input);             system.out.println("loaded");          } catch (filenotfoundexception ex) {             ex.printstacktrace();         }         {         }     } } 

question is, has done similar thing snakeyaml? thoughts might doing wrong?

i see 2 issues:

final inputstream input = new fileinputstream(new file("src/imports/" + value));             final yaml yaml = new yaml(constructor);             return yaml.loadall(input); 

you should using yaml.load(input), not yaml.loadall(input). loadall() method returns multiple objects, construct() method expects return single object.

the other issue may have inconsistent expectations way yaml processing pipeline works:

if think !include works in c preprocessor sticks in contents of included file, way implement handle in presentation stage (parsing) or serialization stage (composing). have implemented in representation stage (constructing), !include returns object, , structure of yaml file must consistent this.

let's have following files:

test1a.yaml

activity: "herding cats" 

test1b.yaml

33 

test1.yaml

favorites: !include test1a.yaml age:       !include test1b.yaml 

this work ok, , equivalent to

favorites:   activity: "herding cats" age: 33 

but following file not work:

!include test1a.yaml !include test1b.yaml 

because there nothing how combine 2 values in larger hierarchy. you'd need this, if want array:

- !include test1a.yaml - !include test1b.yaml 

or, again, handle custom logic in earlier stage such parsing or composing.

alternatively, need tell yaml library starting 2nd document (which error complaining about: expected '<document start>') since yaml supports multiple "documents" (top-level values) in single .yaml file.