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make pagination metadata more robust for offset based pagination #320

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Merged
zachdaniel merged 1 commit into from
May 29, 2025
Merged

make pagination metadata more robust for offset based pagination #320

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34 changes: 31 additions & 3 deletions lib/graphql/resolver.ex
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Original file line number Diff line number Diff line change
Expand Up @@ -1328,9 +1328,37 @@ defmodule AshGraphql.Graphql.Resolver do
end
end

defp paginate_with_offset(%Ash.Page.Offset{results: results, count: count, more?: more?}) do
{:ok, %{results: results, count: count, more?: more?}}
end
defp paginate_with_offset(%Ash.Page.Offset{
results: results,
count: count,
more?: more?,
offset: offset,
limit: limit
}) do
total_pages = get_total_pages(count, limit)
has_next_page = more?
has_previous_page = offset > 0
page_number = get_current_page(%Ash.Page.Offset{limit: limit, offset: offset}, total_pages)
last_page = total_pages

{:ok,
%{
results: results,
count: count,
more?: more?,
has_next_page: has_next_page,
has_previous_page: has_previous_page,
page_number: page_number,
last_page: last_page
}}
end

defp get_total_pages(count, _) when count in [0, nil], do: 1
defp get_total_pages(_, nil), do: 1
defp get_total_pages(total_count, limit), do: ceil(total_count / limit)

defp get_current_page(%Ash.Page.Offset{limit: limit, offset: offset}, total),
do: min(ceil(offset / limit) + 1, total)

defp paginate(_resource, _gql_query, _action, %Ash.Page.Keyset{} = keyset, relay?) do
paginate_with_keyset(keyset, relay?)
Expand Down
53 changes: 42 additions & 11 deletions lib/resource/resource.ex
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Expand Up @@ -3832,6 +3832,46 @@ defmodule AshGraphql.Resource do
]
end

defp add_pagination_metadata(fields, schema, true) do
[
%Absinthe.Blueprint.Schema.FieldDefinition{
description: "Whether or not there is a next page",
identifier: :has_next_page,
module: schema,
name: "has_next_page",
__reference__: ref(__ENV__),
type: %Absinthe.Blueprint.TypeReference.NonNull{of_type: :boolean}
},
%Absinthe.Blueprint.Schema.FieldDefinition{
description: "Whether or not there is a previous page",
identifier: :has_previous_page,
module: schema,
name: "has_previous_page",
__reference__: ref(__ENV__),
type: %Absinthe.Blueprint.TypeReference.NonNull{of_type: :boolean}
},
%Absinthe.Blueprint.Schema.FieldDefinition{
description: "The number of the current page",
identifier: :page_number,
module: schema,
name: "page_number",
__reference__: ref(__ENV__),
type: %Absinthe.Blueprint.TypeReference.NonNull{of_type: :integer}
},
%Absinthe.Blueprint.Schema.FieldDefinition{
description: "The number of the last page",
identifier: :last_page,
module: schema,
name: "last_page",
__reference__: ref(__ENV__),
type: %Absinthe.Blueprint.TypeReference.NonNull{of_type: :integer}
}
| fields
]
end

defp add_pagination_metadata(fields, _, _), do: fields

defp add_count_to_page(fields, schema, true) do
[
%Absinthe.Blueprint.Schema.FieldDefinition{
Expand Down Expand Up @@ -3865,19 +3905,10 @@ defmodule AshGraphql.Resource do
of_type: type
}
}
},
%Absinthe.Blueprint.Schema.FieldDefinition{
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@xantrac xantrac May 28, 2025

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I removed this field definition since it doesn't see be used anywhere

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@zachdaniel zachdaniel May 28, 2025

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When you say its not used anywhere, wouldn't it have been used by the current type?

It remaps more? to has_next_page. Your current code handles that though so it should be fine to remove.

     %Absinthe.Blueprint.Schema.FieldDefinition{


         description: "Whether or not there is a next page",
         identifier: :has_next_page,
         module: schema,
         name: "has_next_page",
         __reference__: ref(__ENV__),
         type: %Absinthe.Blueprint.TypeReference.NonNull{of_type: :boolean}
       },

description: "Whether or not there is a next page",
identifier: :more?,
module: schema,
name: "has_next_page",
__reference__: ref(__ENV__),
type: %Absinthe.Blueprint.TypeReference.NonNull{
of_type: :boolean
}
}
]
|> add_count_to_page(schema, countable?),
|> add_count_to_page(schema, countable?)
|> add_pagination_metadata(schema, countable?),
identifier: String.to_atom("page_of_#{type}"),
module: schema,
name: Macro.camelize("page_of_#{type}"),
Expand Down
136 changes: 136 additions & 0 deletions test/paginate_test.exs
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Expand Up @@ -128,6 +128,142 @@ defmodule AshGraphql.PaginateTest do
:ok
end

test "retruns pagination metadata" do
doc = """
query PaginatedPosts {
paginatedPosts(limit: 1, sort: [{field: TEXT}]) {
count
hasNextPage
hasPreviousPage
pageNumber
lastPage
results{
text
}
}
}
"""

assert {:ok,
%{
data: %{
"paginatedPosts" => %{
"count" => 5,
"hasNextPage" => true,
"hasPreviousPage" => false,
"pageNumber" => 1,
"lastPage" => 5,
"results" => [
%{"text" => "a"}
]
}
}
}} = Absinthe.run(doc, AshGraphql.Test.Schema)
end

test "pagination metadata is correct when offset is 2" do
doc = """
query PaginatedPosts {
paginatedPosts(limit: 1, offset: 2, sort: [{field: TEXT}]) {
count
hasNextPage
hasPreviousPage
pageNumber
lastPage
results{
text
}
}
}
"""

assert {:ok,
%{
data: %{
"paginatedPosts" => %{
"count" => 5,
"hasNextPage" => true,
"hasPreviousPage" => true,
"pageNumber" => 3,
"lastPage" => 5,
"results" => [
%{"text" => "c"}
]
}
}
}} = Absinthe.run(doc, AshGraphql.Test.Schema)
end

test "pagination metadata is correct when offset is 4" do
doc = """
query PaginatedPosts {
paginatedPosts(limit: 1, offset: 4, sort: [{field: TEXT}]) {
count
hasNextPage
hasPreviousPage
pageNumber
lastPage
results{
text
}
}
}
"""

assert {:ok,
%{
data: %{
"paginatedPosts" => %{
"count" => 5,
"hasNextPage" => false,
"hasPreviousPage" => true,
"pageNumber" => 5,
"lastPage" => 5,
"results" => [
%{"text" => "e"}
]
}
}
}} = Absinthe.run(doc, AshGraphql.Test.Schema)
end

test "pagination metadata is correct when the is no limit" do
doc = """
query PaginatedPosts {
paginatedPosts(sort: [{field: TEXT}]) {
count
hasNextPage
hasPreviousPage
pageNumber
lastPage
results{
text
}
}
}
"""

assert {:ok,
%{
data: %{
"paginatedPosts" => %{
"count" => 5,
"hasNextPage" => false,
"hasPreviousPage" => false,
"pageNumber" => 1,
"lastPage" => 1,
"results" => [
%{"text" => "a"},
%{"text" => "b"},
%{"text" => "c"},
%{"text" => "d"},
%{"text" => "e"}
]
}
}
}} = Absinthe.run(doc, AshGraphql.Test.Schema)
end

test "default_limit records are fetched" do
doc = """
query PaginatedPosts {
Expand Down
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