Custom Django model field for storing Numpy 1-d arrays as JSON strings in the database. Useful for handling small amounts of arrays, keeping the relational data scheme.

NumpyArrayField.py

class NumpyArrayField(models.TextField):
    description = "A field to store numpy 1-d arrays as json strings. Requires Pandas."

    def __init__(self, *args, **kwargs):
        """
        Instance the field.
        :param kwargs: max_length - the maximum array length
        """
        super(NumpyArrayField, self).__init__(*args, **kwargs)

    def get_db_prep_value(self, value, *args, **kwargs):
        """
        Converts a numpy 1-dimensional array into a json formatted string for saving in
        the database as a TextField.
        :param value: a numpy array being stored
        :type: np.ndarray
        :return: value, as a json formatted string
        :type: str
        """
        if value is None:
            return None
        return pd.Series(value).to_json(orient='values')  # serialize array

    def to_python(self, value):
        """
        Called by deserialization and during the clean() method used from forms.
        Reconstructs the numpy 1-dimensional array from the json string stored in the database.
        :param value: the array as a json formatted string
        :type: str
        :return: value, as numpy 1-dimensional array
        :type: np.ndarray
        """
        if value is None or isinstance(value, np.ndarray):
            return value
        try:
            return pd.read_json(value)[0].as_matrix()  # numpy array from json string
        except (TypeError, ValueError):
            raise ValidationError("This value must be a json formatted string for a 1-d array.")

    def from_db_value(self, value, expression, connection, context):
        """
        Converts a value as returned by the database to a Python object. It is like the reverse of
        get_prep_value().
        :param value: the array as a json formatted string
        :type: str
        :return: value, as numpy 1-dimensional array
        :type: np.ndarray
        """
        return self.to_python(value)

Thanks!