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fix: backward pagination (#1346)

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Co-authored-by: Thomas Leonard <thomas@loftorbital.com>
Co-authored-by: Laurent  <laurent.riviere.pro@gmail.com>
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Thomas Leonard 2022-09-22 16:01:28 +01:00 committed by GitHub
parent 42a40b4df0
commit 3473fe025e
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2 changed files with 48 additions and 27 deletions
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22
graphene_django/fields.py
View File

@ -152,22 +152,24 @@ class DjangoConnectionField(ConnectionField):
array_length = iterable.count()
else:
array_length = len(iterable)
array_slice_length = (
min(max_limit, array_length) if max_limit is not None else array_length
)
# If after is higher than list_length, connection_from_list_slice
# If after is higher than array_length, connection_from_array_slice
# would try to do a negative slicing which makes django throw an
# AssertionError
slice_start = min(
get_offset_with_default(args.get("after"), -1) + 1, array_length
get_offset_with_default(args.get("after"), -1) + 1,
array_length,
)
array_slice_length = array_length - slice_start
if max_limit is not None and args.get("first", None) is None:
if args.get("last", None) is not None:
slice_start = max(array_length - args["last"], 0)
else:
args["first"] = max_limit
# Impose the maximum limit via the `first` field if neither first or last are already provided
# (note that if any of them is provided they must be under max_limit otherwise an error is raised).
if (
max_limit is not None
and args.get("first", None) is None
and args.get("last", None) is None
):
args["first"] = max_limit
connection = connection_from_array_slice(
iterable[slice_start:],

53
graphene_django/tests/test_query.py
View File

@ -1243,6 +1243,7 @@ def test_should_have_next_page(graphene_settings):
}
@pytest.mark.parametrize("max_limit", [100, 4])
class TestBackwardPagination:
def setup_schema(self, graphene_settings, max_limit):
graphene_settings.RELAY_CONNECTION_MAX_LIMIT = max_limit
@ -1261,8 +1262,8 @@ class TestBackwardPagination:
schema = graphene.Schema(query=Query)
return schema
def do_queries(self, schema):
# Simply last 3
def test_query_last(self, graphene_settings, max_limit):
schema = self.setup_schema(graphene_settings, max_limit=max_limit)
query_last = """
query {
allReporters(last: 3) {
@ -1282,7 +1283,8 @@ class TestBackwardPagination:
e["node"]["firstName"] for e in result.data["allReporters"]["edges"]
] == ["First 3", "First 4", "First 5"]
# Use a combination of first and last
def test_query_first_and_last(self, graphene_settings, max_limit):
schema = self.setup_schema(graphene_settings, max_limit=max_limit)
query_first_and_last = """
query {
allReporters(first: 4, last: 3) {
@ -1302,7 +1304,8 @@ class TestBackwardPagination:
e["node"]["firstName"] for e in result.data["allReporters"]["edges"]
] == ["First 1", "First 2", "First 3"]
# Use a combination of first and last and after
def test_query_first_last_and_after(self, graphene_settings, max_limit):
schema = self.setup_schema(graphene_settings, max_limit=max_limit)
query_first_last_and_after = """
query queryAfter($after: String) {
allReporters(first: 4, last: 3, after: $after) {
@ -1317,7 +1320,8 @@ class TestBackwardPagination:
after = base64.b64encode(b"arrayconnection:0").decode()
result = schema.execute(
query_first_last_and_after, variable_values=dict(after=after)
query_first_last_and_after,
variable_values=dict(after=after),
)
assert not result.errors
assert len(result.data["allReporters"]["edges"]) == 3
@ -1325,20 +1329,35 @@ class TestBackwardPagination:
e["node"]["firstName"] for e in result.data["allReporters"]["edges"]
] == ["First 2", "First 3", "First 4"]
def test_should_query(self, graphene_settings):
def test_query_last_and_before(self, graphene_settings, max_limit):
schema = self.setup_schema(graphene_settings, max_limit=max_limit)
query_first_last_and_after = """
query queryAfter($before: String) {
allReporters(last: 1, before: $before) {
edges {
node {
firstName
}
}
}
}
"""
Backward pagination should work as expected
"""
schema = self.setup_schema(graphene_settings, max_limit=100)
self.do_queries(schema)
def test_should_query_with_low_max_limit(self, graphene_settings):
"""
When doing backward pagination (using last) in combination with a max limit higher than the number of objects
we should really retrieve the last ones.
"""
schema = self.setup_schema(graphene_settings, max_limit=4)
self.do_queries(schema)
result = schema.execute(
query_first_last_and_after,
)
assert not result.errors
assert len(result.data["allReporters"]["edges"]) == 1
assert result.data["allReporters"]["edges"][0]["node"]["firstName"] == "First 5"
before = base64.b64encode(b"arrayconnection:5").decode()
result = schema.execute(
query_first_last_and_after,
variable_values=dict(before=before),
)
assert not result.errors
assert len(result.data["allReporters"]["edges"]) == 1
assert result.data["allReporters"]["edges"][0]["node"]["firstName"] == "First 4"
def test_should_preserve_prefetch_related(django_assert_num_queries):