.. _add_collection:

Add a collection
================

A collection in `eodag` represents a specific kind of Earth Observation data product, defined by its characteristics and metadata.
By following the steps outlined below, you can extend EODAG's capabilities to support additional collections from various providers.

Add collection definition
^^^^^^^^^^^^^^^^^^^^^^^^^

To add a new collection to EODAG, you must add an entry to the file ``eodag/resources/collections.yml``. Here is an
example:

.. code-block:: yaml

    CBERS4_AWFI_L2:
      description: |
        China-Brazil Earth Resources Satellite, CBERS-4 AWFI camera Level-2 product. System corrected images, expect
        some translation error.
      instruments: ["AWFI"]
      constellation: CBERS
      platform: CBERS-4
      processing:level: L2
      keywords: ["AWFI", "CBERS", "CBERS-4", "L2"]
      eodag:sensor_type: OPTICAL
      license: other
      extent: {"spatial": {"bbox": [[-180.0, -90.0, 180.0, 90.0]]}, "temporal": {"interval": [["2014-12-07T00:00:00Z", null]]}}
      title: CBERS-4 AWFI Level-2

The first line ``CBERS4_AWFI_L2:`` is a YAML key corresponding to the name by
which the product will be referred to within EODAG. Note the use of uppercase
and underscores to separate words. This name will be used when searching for
products of the corresponding type.

The following lines need to be indented because they make a dictionary of
configuration information for the collection we are defining. Each bit of
information can usually be found on the provider's catalog. Note how the value
used for the ``keywords`` entry brings together values from other entries such
as ``instruments``, ``processing:level``, ``constellation``, etc.

Add collection to a provider
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

In the directory ``eodag/resources/providers/``, you will find a YAML file for each provider supported by EODAG.
To make EODAG aware of the new collection, you need to add the collection to the ``products`` entry of a provider:

.. code-block:: yaml

    ---
    !provider # MARK: aws_eos
      name: aws_eos
      # ...
      products:
        # ...
        CBERS4_AWFI_L2:
          # ...
          # collection configuration comes here
          # ...

Then for each collection listed under the ``products`` entry, you may
specify default parameters that will be used when searching for products of this
collection:

.. code-block:: yaml

    ---
    !provider
      name: aws_eos
      # ...
      products:
        # ...
        CBERS4_AWFI_L2:
          instruments: ["AWFI"]
          _collection: cbers4
          processing:level: 2

With the example above, when searching for products of the type ``CBERS4_AWFI_L2``, the
search will be performed by default as if we had specified the instruments ``["AWFI"]``, the
collection ``cbers4`` and the processing:level ``2``.
Each of those parameters can be overridden when performing an actual search. Note that
parameters have to be named following the common model used in EODAG (see
`Parameters mapping <params_mapping.rst>`_). Part of the provider search metadata
mapping can also be overridden per collection, by adding a ``metadata_mapping``
section to the collection definition:

.. code-block:: yaml

    ---
    !provider # MARK: aws_eos
      name: aws_eos
      # ...
      products:
        # ...
        CBERS4_AWFI_L2:
          # ... default eodag search parameters
          metadata_mapping_from_product: CBERS4_PAN10M_L2
          metadata_mapping:
            _preview_basename: '{$.sceneID#replace_str("_L4","")}'
            eodag:thumbnail: 'https://s3.amazonaws.com/cbers-meta-pds/{_aws_path}/{_preview_basename}_small.jpeg'

In the example above, we can see that the metadata mapping for the collection
in the context of this provider can be specified in two ways:

- ``metadata_mapping_from_product`` will include an existing metadata mapping
  from another product
- ``metadata_mapping`` will contain a metadata mapping as documented in the
  `section on parameters mapping <params_mapping.rst>`_
