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https://github.com/graphql-python/graphene-django.git
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83 lines
2.9 KiB
Python
83 lines
2.9 KiB
Python
from collections import namedtuple
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from django.db.models import ForeignKey
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from django.db.models.fields.reverse_related import ForeignObjectRel
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from graphene.utils.str_converters import to_snake_case
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from .registry import get_global_registry
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from .utils import get_related_model
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REGISTRY = get_global_registry()
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SELECT = 'select'
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PREFETCH = 'prefetch'
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RelatedSelection = namedtuple('RelatedSelection', ['name', 'fetch_type'])
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def model_fields_as_dict(model):
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return dict((f.name, f) for f in model._meta.get_fields())
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def get_related_fetches_for_model(model, graphql_ast):
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model_fields = model_fields_as_dict(model)
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selections = graphql_ast.selection_set.selections
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graphene_obj_type = REGISTRY.get_type_for_model(model)
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optimizations = {}
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if graphene_obj_type and graphene_obj_type._meta.optimizations:
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optimizations = graphene_obj_type._meta.optimizations
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relateds = []
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for selection in selections:
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selection_name = to_snake_case(selection.name.value)
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selection_field = model_fields.get(selection_name, None)
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try:
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related_model = get_related_model(selection_field)
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except:
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# This is not a ForeignKey or Relation, check manual optimizations
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manual_optimizations = optimizations.get(selection_name)
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if manual_optimizations:
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for manual_select in manual_optimizations.get(SELECT, []):
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relateds.append(RelatedSelection(manual_select, SELECT))
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for manual_prefetch in manual_optimizations.get(PREFETCH, []):
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relateds.append(RelatedSelection(manual_prefetch, PREFETCH))
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continue
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query_name = selection_field.name
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if isinstance(selection_field, ForeignObjectRel):
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query_name = selection_field.field.related_query_name()
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nested_relateds = get_related_fetches_for_model(related_model, selection)
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related_type = PREFETCH # default to prefetch, it's safer
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if isinstance(selection_field, ForeignKey):
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related_type = SELECT # we can only select for ForeignKeys
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if nested_relateds:
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for related in nested_relateds:
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full_name = '{0}__{1}'.format(query_name, related.name)
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nested_related_type = PREFETCH
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if related_type == SELECT and related.fetch_type == SELECT:
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nested_related_type = related_type
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relateds.append(RelatedSelection(full_name, nested_related_type))
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else:
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relateds.append(RelatedSelection(query_name, related_type))
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return relateds
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def optimize_queryset(model, queryset, graphql_ast):
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relateds = get_related_fetches_for_model(model, graphql_ast)
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for related in relateds:
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if related.fetch_type == SELECT:
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queryset = queryset.select_related(related.name)
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else:
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queryset = queryset.prefetch_related(related.name)
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return queryset
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