Python rest_framework.serializers 模块，RelatedField() 实例源码

def get_field_info(self, field):
        """
        Given an instance of a serializer field, return a dictionary
        of metadata about it.
        """
        field_info = OrderedDict()
        field_info['type'] = self.label_lookup[field]
        field_info['required'] = getattr(field, 'required', False)

        attrs = [
            'read_only', 'label', 'help_text',
            'min_length', 'max_length',
            'min_value', 'max_value'
        ]

        for attr in attrs:
            value = getattr(field, attr, None)
            if value is not None and value != '':
                field_info[attr] = force_text(value, strings_only=True)

        if getattr(field, 'child', None):
            field_info['child'] = self.get_field_info(field.child)
        elif getattr(field, 'fields', None):
            field_info['children'] = self.get_serializer_info(field)

        if (not field_info.get('read_only') and
            not isinstance(field, (serializers.RelatedField, serializers.ManyRelatedField)) and
                hasattr(field, 'choices')):
            field_info['choices'] = [
                {
                    'value': choice_value,
                    'display_name': force_text(choice_name, strings_only=True)
                }
                for choice_value, choice_name in field.choices.items()
            ]

        return field_info

def field_to_schema(field):
    title = force_text(field.label) if field.label else ''
    description = force_text(field.help_text) if field.help_text else ''

    if isinstance(field, serializers.ListSerializer):
        child_schema = field_to_schema(field.child)
        return coreschema.Array(
            items=child_schema,
            title=title,
            description=description
        )
    elif isinstance(field, serializers.Serializer):
        return coreschema.Object(
            properties=OrderedDict([
                (key, field_to_schema(value))
                for key, value
                in field.fields.items()
            ]),
            title=title,
            description=description
        )
    elif isinstance(field, serializers.ManyRelatedField):
        return coreschema.Array(
            items=coreschema.String(),
            title=title,
            description=description
        )
    elif isinstance(field, serializers.RelatedField):
        return coreschema.String(title=title, description=description)
    elif isinstance(field, serializers.MultipleChoiceField):
        return coreschema.Array(
            items=coreschema.Enum(enum=list(field.choices.keys())),
            title=title,
            description=description
        )
    elif isinstance(field, serializers.ChoiceField):
        return coreschema.Enum(
            enum=list(field.choices.keys()),
            title=title,
            description=description
        )
    elif isinstance(field, serializers.BooleanField):
        return coreschema.Boolean(title=title, description=description)
    elif isinstance(field, (serializers.DecimalField, serializers.FloatField)):
        return coreschema.Number(title=title, description=description)
    elif isinstance(field, serializers.IntegerField):
        return coreschema.Integer(title=title, description=description)

    if field.style.get('base_template') == 'textarea.html':
        return coreschema.String(
            title=title,
            description=description,
            format='textarea'
        )
    return coreschema.String(title=title, description=description)