docs/reference/api-extensions/custom-result-builders.rst

======================
Custom Result Builders
======================

How to build your own Result Builder

Before starting
---------------

We suggest reaching out on `slack <https://join.slack.com/t/hamilton-opensource/shared\_invite/zt-1bjs72asx-wcUTgH7q7QX1igiQ5bbdcg>`__\
or via a github issue, if you have a use case for a custom result builder. Knowing about your use case and talking\
through it can help ensure we aren't duplicating effort, and we can help steer you in the right direction.

What you need to do
-------------------

You need to implement a class that implements a single function - see \
`github code <https://github.com/dagworks-inc/hamilton/blob/main/hamilton/base.py#L18-L28>`__:

.. code-block:: python

    class ResultMixin(object):
        """Base class housing the static function.

        Why a static function? That's because certain frameworks can only pickle a static function, not an entire
        object.
        """
        @staticmethod
        @abc.abstractmethod
        def build_result(**outputs: typing.Dict[str, typing.Any]) -> typing.Any:
            """This function builds the result given the computed values."""
            pass

E.g.

.. code-block:: python

    import typing
    from hamilton import base
    class MyCustomBuilder(base.ResultMixin):
         # add a constructor if you need to
         @staticmethod
         def build_result(**outputs: typing.Dict[str, typing.Any]) -> YOUR_RETURN_TYPE:
             """Custom function you fill in"""
             # your logic would go here
             return OBJECT_OF_YOUR_CHOOSING

How to use it
-------------

You would then pair that with a graph adapter that takes in a ResultMixin object. E.g. ``SimplePythonGraphAdapter``.
See :doc:`../graph-adapters/index` for which ones take in a custom ResultMixin object.