Mivot writer

CHANGES.rst

@@ -50,7 +50,7 @@ Enhancements and Fixes
 
 - MIVOT module: the model references in the dictionaries that are used to build ``MivotInstance``
   objects are made more consistent [#551]
-
+  
 - RegTAP constraints involving tables other than rr.resource are now
   done via subqueries for less duplication of interfaces. [#562, #572]
 
@@ -62,7 +62,10 @@ Enhancements and Fixes
 
 - Updated getdatalink to be consistent with iter_datalinks. [#613]
 
-
+- Extending the MIVOT module with the ability to build annotations component by component
+  and put them into a VOTable. [#627]
+
+
 Deprecations and Removals
 -------------------------
 

docs/mivot/index.rst

@@ -1,8 +1,10 @@
+.. _index:
+
 ********************
 MIVOT (`pyvo.mivot`)
 ********************
 
-This module contains the new feature of annotations in VOTable.
+This module contains the new feature handling model annotations in VOTable.
 Astropy version >= 6.0 is required.
 
 Introduction
@@ -42,8 +44,8 @@ Some of the examples have been provided by a special end-point of the Vizier con
 (https://cdsarc.cds.unistra.fr/beta/viz-bin/mivotconesearch) that maps query results to this model.
 
 .. image:: _images/mangoEpochPosition.png
-  :width: 500
-  :alt: EpochPropagation class used to validate this api.
+   :width: 500
+   :alt: EpochPropagation class used to validate this api.
 
 It is to be noted that the Vizier service does not annotate errors at the time of writing (Q1 2024)
 
@@ -56,185 +58,19 @@ which allows to get (and set) Mivot blocks from/into VOTables as an XML element
     epoch propagation use case:
 
     - ``JOIN`` features are not supported.
-    - ``TEMPLATES`` with more than one ``INSANCE`` not supported.
-
-Integrated Readout
-------------------
-The ``ModelViewer`` module manages access to data mapped to a model through dynamically
-generated objects (``MivotInstance``class).
-The example below shows how a VOTable, resulting from a cone-search query which data are mapped
-to the ``EpochPosition`` class, can be consumed.
-
-.. doctest-remote-data::
-    >>> import astropy.units as u
-    >>> from astropy.coordinates import SkyCoord
-    >>> from pyvo.dal.scs import SCSService
-    >>> from pyvo.utils.prototype import activate_features
-    >>> from pyvo.mivot.version_checker import check_astropy_version
-    >>> from pyvo.mivot.viewer.mivot_viewer import MivotViewer
-    >>> activate_features("MIVOT")
-    >>> if check_astropy_version() is False:
-    ...    pytest.skip("MIVOT test skipped because of the astropy version.")
-    >>> scs_srv = SCSService("https://cdsarc.cds.unistra.fr/beta/viz-bin/mivotconesearch/I/239/hip_main")
-    >>> m_viewer = MivotViewer(
-    ...     scs_srv.search(
-    ...         pos=SkyCoord(ra=52.26708 * u.degree, dec=59.94027 * u.degree, frame='icrs'),
-    ...         radius=0.05
-    ...     )
-    ... )
-    >>> mivot_instance = m_viewer.dm_instance
-    >>> print(mivot_instance.dmtype)
-    mango:EpochPosition
-    >>> print(mivot_instance.coordSys.spaceRefFrame.value)
-    ICRS
-    >>> while m_viewer.next():
-    ...     print(f"position: {mivot_instance.latitude.value} {mivot_instance.longitude.value}")
-    position: 59.94033461 52.26722684
-
-
-In this example, the data readout is totally managed by the ``MivotViewer`` instance.
-The ``astropy.io.votable`` API is encapsulated in this module.
-
-Model leaves (class attributes) are complex types that provide additional information:
-
-- ``value``: attribute value
-- ``dmtype``: attribute type such as defined in the Mivot annotations
-- ``unit``: attribute unit such as defined in the Mivot annotations
-- ``ref``: identifier of the table column mapped on the attribute
-
-The model view on a data row can also be passed as a Python dictionary
-using the ``to_dict()`` method of ``MivotInstance``. 
-
-.. code-block:: python
-    :caption: Working with a model view as a dictionary
-              (the JSON layout has been squashed for display purpose)
-
-	from pyvo.mivot import MivotViewer
-    from pyvo.mivot.utils.dict_utils import DictUtils
-
-    m_viewer = MivotViewer(path_to_votable)
-    mivot_instance = m_viewer.dm_instance
-    mivot_object_dict = mivot_object.to_dict()
-
-    DictUtils.print_pretty_json(mivot_object_dict)
-	{
-        "dmtype": "mango:EpochPosition",
-        "longitude": {"value": 359.94372764, "unit": "deg"},
-        "latitude": {"value": -0.28005255, "unit": "deg"},
-        "pmLongitude": {"value": -5.14, "unit": "mas/yr"},
-        "pmLatitude": {"value": -25.43, "unit": "mas/yr"},
-        "epoch": {"value": 1991.25, "unit": "year"},
-        "coordSys": {
-            "dmtype": "coords:SpaceSys",
-            "dmid": "ICRS",
-            "dmrole": "coords:Coordinate.coordSys",
-            "spaceRefFrame": {"value": "ICRS"},
-        },
-    }
-
-- It is recommended to use a copy of the
-  dictionary as it will be rebuilt each time the ``to_dict()`` method is invoked.
-- The default representation of ``MivotInstance`` instances is made with a pretty
-  string serialization of this dictionary (method ``__repr__()``).
-- An extended version of the object dictionary e.g. with information about where 
-  the values were picked from from, is available  using the method ``to_hk_dict()``.
-
-Per-Row Readout
----------------
-
-The annotation schema can also be applied to table rows read outside of the ``MivotViewer``
-with the `astropy.io.votable` API:
-
-.. code-block:: python
-    :caption: Accessing the model view of Astropy table rows
-
-    votable = parse(path_to_votable)
-    table = votable.resources[0].tables[0]
-    # init the viewer
-    mivot_viewer = MivotViewer(votable, resource_number=0)
-    mivot_object = mivot_viewer.dm_instance
-    # and feed it with the table row
-    read = []
-    for rec in table.array:
-        mivot_object.update(rec)
-        read.append(mivot_object.longitude.value)
-        # show that the model retrieve the correct data values
-        assert rec["RAICRS"] == mivot_object.longitude.value
-        assert rec["DEICRS"] == mivot_object.latitude.value
-
-In this case, it is up to the user to ensure that the read data rows are those mapped by the Mivot annotations.
-
-Get a SkyCoord Instance Directly From the Annotations
------------------------------------------------------
-
-Once you get a ``MivotInstance`` representing the last row read, you can use it to create an ``astropy.SkyCoord`` object.
-
-.. code-block:: python
-    :caption: Accessing the model view of Astropy table rows
-
-	from pyvo.mivot import MivotViewer
-
-    m_viewer = MivotViewer(path_to_votable)
-    mivot_instance = m_viewer.dm_instance
-    print(mivot_instance.get_SkyCoord())
-    <SkyCoord (ICRS): (ra, dec) in deg(52.26722684, 59.94033461)
-          (pm_ra_cosdec, pm_dec) in mas / yr(-0.82, -1.85)>
-
-This feature works under the condition that the annotations contain a valid instance of ``mango:EPochPosition``, otherwise
-a ``NoMatchingDMTypeError`` is thrown. 
-Although not a standard at the time of writing, the class structure supported by this implementation must match the figure above.
-
-
-For XML Hackers
----------------
-
-The model instances can also be serialized as XML elements that can be parsed with XPath queries.
-
-.. code-block:: python
-    :caption: Accessing the XML view of the mapped model instances
-
-    with MivotViewer(path_to_votable) as mivot_viewer:
-        while mivot_viewer.next():
-        	xml_view = mivot_viewer.xml_view
-        	# do whatever you want with this XML element
-
-It to be noted that ``mivot_viewer.xml_view`` is a shortcut
-for ``mivot_viewer.xml_view.view`` where ``mivot_viewer.xml_view``
-is is an instance of ``pyvo.mivot.viewer.XmlViewer``.
-This object provides many functions facilitating the XML parsing.
-
-Class Generation in a Nutshell
-------------------------------
-
-MIVOT reconstructs model structures with 3 elements:
-
-- ``INSTANCE`` for the objects
-- ``ATTRIBUTE`` for the attributes
-- ``COLLECTION`` for the elements with a cardinality greater than 1
-
-The role played by each of these elements in the model hierarchy is defined
-by its ``@dmrole`` XML attribute. Types of both ``INSTANCE`` and ``ATTRIBUTE`` are defined by
-their ``@dmtype`` XML attributes.
-
-``MivotInstance`` classes are built by following MIVOT annotation structure:
-
-- ``INSTANCE`` are represented by Python classes
-- ``ATTRIBUTE`` are represented by Python class fields
-- ``COLLECTION`` are represented by Python lists ([])
-
-``@dmrole`` and ``@dmtype`` cannot be used as Python keywords as such, because they are built from VO-DML
-identifiers, which have the following structure: ``model:a.b``.
-
-- Only the last part of the path is kept for attribute names.
-- For class names, forbidden characters (``:`` or ``.``) are replaced with ``_``.
-- Original ``@dmtype`` are kept as attributes of generated Python objects.
-- The structure of the ``MivotInstance`` objects can be inferred from the mapped model in 2 different ways:
+    - ``TEMPLATES`` with more than one ``INSTANCE`` not supported.
+
+
+Using the MIVOT package
+=======================
+
+The ``pyvo.mivot`` module can be used to either read or build annotations.
+
+.. toctree::
+
+   viewer
+   writer
 
-  - 1.  From the MIVOT instance property ``MivotInstance.to_dict()`` a shown above.
-        This is a pure Python dictionary but its access can be slow because it is generated
-        on the fly each time the property is invoked.
-  - 2.  From the internal  class dictionary ``MivotInstance.__dict__``
-        (see the Python `data model <https://docs.python.org/3/reference/datamodel.html>`_).
 
 Reference/API
 =============
@@ -244,3 +80,4 @@ Reference/API
 .. automodapi:: pyvo.mivot.seekers
 .. automodapi:: pyvo.mivot.features
 .. automodapi:: pyvo.mivot.utils
+.. automodapi:: pyvo.mivot.writer