How to create nested DataElement?

[qarmin]

Recently I started to try to implement worklist client in dicom-rs and pynetdicom

In pynetdicom when I use this keys which create data element

'PatientName=', 'PatientID',
        'ScheduledProcedureStepSequence[0].ScheduledProcedureStepStartDate=19951015'

I see in server side(orthantc) this:

I0601 13:41:19.497090 PluginsManager.cpp:161] (plugins) Received worklist query from remote modality PYNETDICOM:
{
	"0010,0010" : "",
	"0010,0020" : "",
	"0040,0100" : 
	[
		{
			"0040,0002" : "19951015"
		}
	]
}

In dicom-rs I wanted to do same thing, patient id and patient name is patient id is simple to use

            obj.put(DataElement::new(
                tags::PATIENT_NAME,
                VR::LO,
                PrimitiveValue::from("*"),
            ));
            obj.put(DataElement::new(
                tags::PATIENT_ID,
                VR::LO,
                PrimitiveValue::from(""),
            ));

For start date I created something like

            let start_date_sequence:DataElement<InMemDicomObject, InMemFragment> = DataElement::new(
                tags::SCHEDULED_PROCEDURE_STEP_START_DATE,
                VR::LO,
                PrimitiveValue::from("19951015"),
            );

            let scheduled_procedure_step_sequence = DataElement::new(
                tags::SCHEDULED_PROCEDURE_STEP_SEQUENCE,
                VR::SQ,
                Value::new_sequence(smallvec![start_date_sequence], Length::UNDEFINED),
            );
            obj.push(scheduled_procedure_step_sequence);

but push prints error

error[E0308]: mismatched types
   --> src/other.rs:97:21
    |
97  |             obj.put(scheduled_procedure_step_sequence);
    |                 --- ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `DataElement<InMemDicomObject, ...>`, found `DataElement<DataElement<..., ...>>`
    |                 |
    |                 arguments to this method are incorrect
    |
    = note: expected struct `DataElement<InMemDicomObject, Vec<u8>>`
               found struct `DataElement<DataElement<InMemDicomObject, Vec<u8>>, [u8; 0]>`
note: method defined here
   --> /home/rafal/.cargo/registry/src/github.com-1ecc6299db9ec823/dicom-object-0.5.4/src/mem.rs:541:12
    |
541 |     pub fn put(&mut self, elt: InMemElement<D>) -> Option<InMemElement<D>> {
    |            ^^^

How can I mimic python behaviour?

[Enet4]

The items within a sequence need to be objects themselves, rather than data elements. So the way to go would be creating the full nested data set as an independent DICOM object:

let scheduled_procedure_step_sequence_set = InMemDicomObject::from_iter([
    DataElement::new(
        tags::SCHEDULED_PROCEDURE_STEP_START_DATE,
        VR::LO,
        PrimitiveValue::from("19951015"),
    )
]);

Then you can add this as a single item to the sequence:

let e = DataElement::new(
    tags::SCHEDULED_PROCEDURE_STEP_SEQUENCE,
    VR::SQ,
    Value::new_sequence(smallvec![scheduled_procedure_step_sequence_set], Length::UNDEFINED),
);
obj.push(e);

There could be easier ways to do this in the future, maybe starting with a path-like syntax for DICOM data set traversal.

[qarmin]

New error looks better, but still I cannot find way to compile this:

            let mut obj =
                parse_queries(&q).whatever_context("Could not build query object from terms")?;
            let scheduled_procedure_step_sequence_set = InMemDicomObject::from_element_iter([
                DataElement::new(
                    tags::SCHEDULED_PROCEDURE_STEP_START_DATE,
                    VR::LO,
                    PrimitiveValue::from("19951015"),
                )
            ]);
            let scheduled_procedure_step_sequence = DataElement::new(
                tags::SCHEDULED_PROCEDURE_STEP_SEQUENCE,
                VR::SQ,
                Value::new_sequence(smallvec![scheduled_procedure_step_sequence_set], Length::UNDEFINED),
            );
            obj.put(scheduled_procedure_step_sequence);

prints error

error[E0308]: mismatched types
   --> src/other.rs:77:21
    |
77  |             obj.put(scheduled_procedure_step_sequence);
    |                 --- ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `DataElement<InMemDicomObject, ...>`, found `DataElement<InMemDicomObject>`
    |                 |
    |                 arguments to this method are incorrect
    |
    = note: expected struct `DataElement<_, Vec<u8>>`
               found struct `DataElement<_, [u8; 0]>`
note: method defined here
   --> /home/rafal/.cargo/registry/src/github.com-1ecc6299db9ec823/dicom-object-0.5.4/src/mem.rs:541:12
    |
541 |     pub fn put(&mut self, elt: InMemElement<D>) -> Option<InMemElement<D>> {
    |            ^^^

[Enet4]

Hmm, it's a type mismatch in the DICOM object type parameters. The first one is for nested data sets, the second one for pixel data fragments. The helper constructor new_sequence is being unnecessarily strict right now, so the way to fix this is to build the sequence value manually.

let scheduled_procedure_step_sequence = DataElement::new(
    tags::SCHEDULED_PROCEDURE_STEP_SEQUENCE,
    VR::SQ,
    Value::Sequence {
        items: smallvec![scheduled_procedure_step_sequence_set],
        size: Length::UNDEFINED
    },
);
obj.put(scheduled_procedure_step_sequence);