How to use the crash.models.Symbols function in crash

from rest_framework import serializers

from crash.models import Symbols, Crash
from crash.utils import parse_debug_meta_info


__all__ = ['SymbolsSerializer']


class SymbolsSerializer(serializers.HyperlinkedModelSerializer):
    file = serializers.FileField(required=True)
    debug_id = serializers.CharField(default='', required=False, allow_blank=True)
    debug_file = serializers.CharField(default='', required=False, allow_blank=True)

    class Meta:
        model = Symbols
        fields = ('id', 'file', 'file_size', 'debug_id', 'debug_file',
                  'created', 'modified')
        read_only_fields = ('created', 'modified')
        validators = [
            serializers.UniqueTogetherValidator(
                queryset=Symbols.objects.all(),
                fields=('debug_id', 'debug_file')
            )
        ]

    def create(self, validated_data):
        if not validated_data.get('debug_id') or \
                not validated_data.get('debug_file'):
            file = validated_data['file']
            try:
                head = file.readline().rstrip()

def get_prefix(model_name):
    model_path_prefix = {
        Crash: ('minidump', 'minidump_archive'),
        Feedback: ('blackbox', 'system_logs', 'feedback_attach', 'screenshot'),
        Symbols: ('symbols',),
        Version: ('build',),
        SparkleVersion: ('sparkle',)
    }
    return model_path_prefix[model_name]

@bulk_delete.register(Symbols)
def _(cls, qs):
    if settings.DEFAULT_FILE_STORAGE == 'storages.backends.s3boto.S3BotoStorage':
        qs = s3_bulk_delete(qs, file_fields=['file'], s3_fields=['symbols'])

    result = dict()
    result['count'] = qs.count()
    result['size'] = qs.get_size()
    elements = list(qs.values_list('id', 'created'))
    result['elements'] = map(lambda x: dict(id=x[0], element_created=x[1].strftime("%d. %B %Y %I:%M%p")), elements)
    qs.delete()
    return result

def regenerate_stacktrace(self, request, queryset):
        for i in queryset:
            signature("tasks.processing_crash_dump", args=(i.pk,)).apply_async(queue='default')
    regenerate_stacktrace.short_description = 'Regenerate stacktrace'

    def get_form(self, request, obj=None, **kwargs):
        if CRASH_TRACKER != 'Sentry':
            try:
                self.readonly_fields.remove('sentry_link_field')
            except ValueError:
                pass
        return super(CrashAdmin, self).get_form(request, obj, **kwargs)


@admin.register(Symbols)
class SymbolsAdmin(admin.ModelAdmin):
    readonly_fields = ('created', 'modified', )
    list_display = ('created', 'modified', 'debug_file', 'debug_id',)
    list_display_links = ('created', 'modified', 'debug_file', 'debug_id',)
    form = SymbolsAdminForm