Allow the after cursor to be an empty string (same as offset: 0)

integration_tests/cursor.lua

@@ -0,0 +1,205 @@
+Test.gql("forward pagination", function(t)
+	local fetchTeams = function(after)
+		t.query(string.format([[
+			query {
+				teams(first:5 after:"%s") {
+					pageInfo {
+						hasNextPage
+						endCursor
+					}
+					edges {
+						node {
+							slug
+						}
+						cursor
+					}
+				}
+			}
+		]], after))
+	end
+
+	fetchTeams("")
+	t.check {
+		data = {
+			teams = {
+				pageInfo = {
+					hasNextPage = true,
+					endCursor = Save("endCursor"),
+				},
+				edges = {
+					{
+						node = {
+							slug = "slug-1",
+						},
+						cursor = Ignore(),
+					},
+					{
+						node = {
+							slug = "slug-10",
+						},
+						cursor = Ignore(),
+					},
+					{
+						node = {
+							slug = "slug-11",
+						},
+						cursor = Ignore(),
+					},
+					{
+						node = {
+							slug = "slug-12",
+						},
+						cursor = Ignore(),
+					},
+					{
+						node = {
+							slug = "slug-13",
+						},
+						cursor = Save("lastNodeInPageCursor"),
+					},
+				},
+			},
+		},
+	}
+
+	assert(State.lastNodeInPageCursor == State.endCursor, "lastNodeInPageCursor is not equal to endCursor")
+
+	fetchTeams(State.endCursor)
+	t.check {
+		data = {
+			teams = {
+				pageInfo = {
+					hasNextPage = true,
+					endCursor = Save("endCursor"),
+				},
+				edges = {
+					{
+						node = {
+							slug = "slug-14",
+						},
+						cursor = Ignore(),
+					},
+					{
+						node = {
+							slug = "slug-15",
+						},
+						cursor = Ignore(),
+					},
+					{
+						node = {
+							slug = "slug-16",
+						},
+						cursor = Ignore(),
+					},
+					{
+						node = {
+							slug = "slug-17",
+						},
+						cursor = Ignore(),
+					},
+					{
+						node = {
+							slug = "slug-18",
+						},
+						cursor = Save("lastNodeInPageCursor"),
+					},
+				},
+			},
+		},
+	}
+
+	assert(State.lastNodeInPageCursor == State.endCursor, "lastNodeInPageCursor is not equal to endCursor")
+
+	fetchTeams(State.endCursor)
+	t.check {
+		data = {
+			teams = {
+				pageInfo = {
+					hasNextPage = true,
+					endCursor = Save("endCursor"),
+				},
+				edges = {
+					{
+						node = {
+							slug = "slug-19",
+						},
+						cursor = Ignore(),
+					},
+					{
+						node = {
+							slug = "slug-2",
+						},
+						cursor = Ignore(),
+					},
+					{
+						node = {
+							slug = "slug-20",
+						},
+						cursor = Ignore(),
+					},
+					{
+						node = {
+							slug = "slug-3",
+						},
+						cursor = Ignore(),
+					},
+					{
+						node = {
+							slug = "slug-4",
+						},
+						cursor = Save("lastNodeInPageCursor"),
+					},
+
+				},
+			},
+		},
+	}
+
+	assert(State.lastNodeInPageCursor == State.endCursor, "lastNodeInPageCursor is not equal to endCursor")
+
+	fetchTeams(State.endCursor)
+	t.check {
+		data = {
+			teams = {
+				pageInfo = {
+					hasNextPage = false,
+					endCursor = Save("endCursor"),
+				},
+				edges = {
+					{
+						node = {
+							slug = "slug-5",
+						},
+						cursor = Ignore(),
+					},
+					{
+						node = {
+							slug = "slug-6",
+						},
+						cursor = Ignore(),
+					},
+					{
+						node = {
+							slug = "slug-7",
+						},
+						cursor = Ignore(),
+					},
+					{
+						node = {
+							slug = "slug-8",
+						},
+						cursor = Ignore(),
+					},
+					{
+						node = {
+							slug = "slug-9",
+						},
+						cursor = Save("lastNodeInPageCursor"),
+					},
+				},
+			},
+		},
+	}
+
+	assert(State.lastNodeInPageCursor == State.endCursor, "lastNodeInPageCursor is not equal to endCursor")
+end)

internal/graph/pagination/cursor.go

@@ -9,6 +9,7 @@ import (
 	"strconv"
 
 	"github.com/btcsuite/btcutil/base58"
+	"github.com/nais/api/internal/graph/apierror"
 )
 
 var cursorVersions = map[string]func(c *Cursor, i []byte) error{
@@ -17,6 +18,11 @@ var cursorVersions = map[string]func(c *Cursor, i []byte) error{
 
 type Cursor struct {
 	Offset int `json:"offset"`
+	empty  bool
+}
+
+func (c *Cursor) valid() bool {
+	return c != nil && !c.empty
 }
 
 func (c Cursor) MarshalGQLContext(_ context.Context, w io.Writer) error {
@@ -31,14 +37,18 @@ func (c Cursor) MarshalGQLContext(_ context.Context, w io.Writer) error {
 
 func (c *Cursor) UnmarshalGQLContext(_ context.Context, v interface{}) error {
 	if s, ok := v.(string); ok {
+		if s == "" {
+			c.empty = true
+			return nil
+		}
 		b := base58.Decode(s)
 		version, cursor, ok := bytes.Cut(b, []byte{':'})
 		if !ok {
-			return fmt.Errorf("invalid cursor format")
+			return apierror.Errorf("Unsupported cursor format")
 		}
 		parseCursor, ok := cursorVersions[string(version)]
 		if !ok {
-			return fmt.Errorf("unsupported cursor version")
+			return apierror.Errorf("Unsupported cursor version: %q", string(version))
 		}
 		if err := parseCursor(c, cursor); err != nil {
 			return err

internal/graph/pagination/cursor_test.go

@@ -6,6 +6,7 @@ import (
 	"testing"
 
 	"github.com/google/go-cmp/cmp"
+	"github.com/google/go-cmp/cmp/cmpopts"
 )
 
 func TestCursor_MarshalGQLContext(t *testing.T) {
@@ -58,7 +59,7 @@ func TestCursor_UnmarshalGQLContext(t *testing.T) {
 				t.Fatal(err)
 			}
 
-			if diff := cmp.Diff(tc.expected, c); diff != "" {
+			if diff := cmp.Diff(tc.expected, c, cmpopts.IgnoreUnexported(Cursor{})); diff != "" {
 				t.Errorf("diff: -want +got\n%s", diff)
 			}
 		})

internal/graph/pagination/relay.go

@@ -40,12 +40,14 @@ func ParsePage(first *int, after *Cursor, last *int, before *Cursor) (*Paginatio
 	}
 
 	switch {
-	case first != nil && before != nil:
+	case first != nil && before.valid():
 		return nil, apierror.Errorf("first and before cannot be used together")
 	case last != nil && after != nil:
 		return nil, apierror.Errorf("last and after cannot be used together")
 	case last != nil && before == nil:
 		return nil, apierror.Errorf("last must be used with before")
+	case before != nil && before.empty:
+		return nil, apierror.Errorf("before cannot be empty")
 	}
 
 	if first != nil {
@@ -62,7 +64,7 @@ func ParsePage(first *int, after *Cursor, last *int, before *Cursor) (*Paginatio
 		p.limit = l
 	}
 
-	if after != nil {
+	if after != nil && !after.empty {
 		p.offset = after.Offset + 1
 	} else if before != nil {
 		p.offset = before.Offset - int(p.Limit())