# Extension containing a NamedDomainObjectContainer

**URL:** <https://discuss.gradle.org/t/extension-containing-a-nameddomainobjectcontainer/8651>\
**Category:** Help/Discuss\
**Created:** [April 7, 2015, 4:14am UTC](https://discuss.gradle.org/t/extension-containing-a-nameddomainobjectcontainer/8651 "2015-04-07T04:14:32Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![Steve\_Ebersole](https://sea1.discourse-cdn.com/gradle/user_avatar/discuss.gradle.org/steve_ebersole/32/9763_2.png) [@Steve\_Ebersole](https://discuss.gradle.org/u/Steve_Ebersole)\
**Post date:** [April 7, 2015, 4:14am UTC](https://discuss.gradle.org/t/extension-containing-a-nameddomainobjectcontainer/8651/1 "2015-04-07T04:14:32Z")

</div>

I am working on a plugin that defines an Extension where I would like that Extension to hold a NamedDomainObjectContainer. It is a JAXB/XJC plugin. The top-level Extension holds information for processing all XSDs. And for each XSD to be processed I’d like to have a NamedDomainObjectContainer holding descriptors of that config. I visualize the DSL as:

```
jaxb {
  outputDir = ...

  schemas {
    cfg {
      xsd = file( ... )
      ...
    }
    hbm {
      xsd = file(...)
      xjcBinding = file(...)
      ..
    }
  }
}

```

cfg and hbm are meant to represent the named domain objects. The way the plugin is structured is that the plugin registers the extension:

```
JaxbExtension extension = project.getExtensions().create( "jaxb", JaxbExtension, project )

```

and JaxbExtension holds the NamedDomainObjectContainer:

```
class JaxbExtension {
  ..
  final NamedDomainObjectContainer<SchemaDescriptor> schemas;
}

```

For the life of me though I cannot figure out how to wire this all up. I have tried the DSL snippet above, but end up with:  
\> Could not find method schemas() for arguments [build\_8dyounopx7k45aqwxkd22bp9p$\_run\_closure4\_closure6@481ef3e] on project ‘:java6-module’.

I also tried without the schemas {} grouping:  
\> Could not find method cfg() for arguments [build\_8dyounopx7k45aqwxkd22bp9p$\_run\_closure4\_closure6@7b42a00f] on project ‘:java6-module’.

Is what I am trying possible? Any pointers on implementing it?

---

<div class="post-metadata">

**Author:** ![mark\_vieira](https://sea1.discourse-cdn.com/gradle/user_avatar/discuss.gradle.org/mark_vieira/32/5396_2.png) [@mark\_vieira](https://discuss.gradle.org/u/mark_vieira)\
**Post date:** [April 7, 2015, 5:14am UTC](https://discuss.gradle.org/t/extension-containing-a-nameddomainobjectcontainer/8651/2 "2015-04-07T05:14:54Z")

</div>

You have to provide a little bit more than just a instance variable definition on your extension object. First you have to create a container. You can do this by calling `Project.container()`. Add the following to the constructor of `JaxbExtension`.

```
this.schemas = project.container(SchemaDescriptor)

```

You’ll also have to add a method that takes a closure as an argument which configures your container. Add the following method to your extension object.

```
def schemas(Closure config) {
    this.schemas.configure(config)
}

```

Last, you’ll want to ensure that the container type, in this case `SchemaDefinition`, has a property called ‘name’ and a public constructor which takes the ‘name’ as a `String` argument.

---

<div class="post-metadata">

**Author:** ![Steve\_Ebersole](https://sea1.discourse-cdn.com/gradle/user_avatar/discuss.gradle.org/steve_ebersole/32/9763_2.png) [@Steve\_Ebersole](https://discuss.gradle.org/u/Steve_Ebersole)\
**Post date:** [April 7, 2015, 12:29pm UTC](https://discuss.gradle.org/t/extension-containing-a-nameddomainobjectcontainer/8651/3 "2015-04-07T12:29:15Z")

</div>

Thanks Mark. I actually do have the call to `Project#container`, I just did not include it in the snippet above. Here is a more complete picture of what I have there:

```
class JaxbExtension {
  ...
  final NamedDomainObjectContainer<SchemaDescriptor> schemas;

  public JaxbExtension(Project project) {
    this.project = project;

    ...

    // Create a dynamic container for SchemaDescriptor definitions by the user
    schemas = project.container( SchemaDescriptor, new SchemaDescriptorFactory( project ) )
}
}

```

and:

```
class SchemaDescriptorFactory implements NamedDomainObjectFactory<SchemaDescriptor> {
  final Project project;

  SchemaDescriptorFactory(Project project) {
    this.project = project
  }

  @Override
  SchemaDescriptor create(String name) {
    return new SchemaDescriptor( project, name )
  }
}

```

Sorry, I should have posted that before.

I guess what I am missing now is the configure method on JaxbExtension. I will try that now. Thanks again!

---

<div class="post-metadata">

**Author:** ![Steve\_Ebersole](https://sea1.discourse-cdn.com/gradle/user_avatar/discuss.gradle.org/steve_ebersole/32/9763_2.png) [@Steve\_Ebersole](https://discuss.gradle.org/u/Steve_Ebersole)\
**Post date:** [April 7, 2015, 1:12pm UTC](https://discuss.gradle.org/t/extension-containing-a-nameddomainobjectcontainer/8651/4 "2015-04-07T13:12:41Z")

</div>

Adding the `schemas(Closure)` method to JaxbExtension dids the trick! Thanks again Mark!