fix: Allow primary field declarations on one-many (#2796)

## Relevant issue(s)

Resolves #961

## Description

Allows primary field declarations on one side of one-many.

Declaring it as primary doesn't do anything, but there is no reason it
shouldn't be permitted and it definitely shouldn't have errored the way
it did.

internal/request/graphql/schema/collection.go

@@ -676,16 +676,19 @@ func finalizeRelations(
 			}
 
 			if !otherColFieldDescription.HasValue() || otherColFieldDescription.Value().Kind.Value().IsArray() {
-				// Relations only defined on one side of the object are possible, and so if this is one of them
-				// or if the other side is an array, we need to add the field to the schema (is primary side).
-				definition.Schema.Fields = append(
-					definition.Schema.Fields,
-					client.SchemaFieldDescription{
-						Name: field.Name,
-						Kind: field.Kind.Value(),
-						Typ:  cTypeByFieldNameByObjName[definition.Schema.Name][field.Name],
-					},
-				)
+				if _, exists := definition.Schema.GetFieldByName(field.Name); !exists {
+					// Relations only defined on one side of the object are possible, and so if this is one of them
+					// or if the other side is an array, we need to add the field to the schema (is primary side)
+					// if the field has not been explicitly declared by the user.
+					definition.Schema.Fields = append(
+						definition.Schema.Fields,
+						client.SchemaFieldDescription{
+							Name: field.Name,
+							Kind: field.Kind.Value(),
+							Typ:  cTypeByFieldNameByObjName[definition.Schema.Name][field.Name],
+						},
+					)
+				}
 			}
 
 			otherIsEmbedded := len(otherColDefinition.Value().Description.Fields) == 0

tests/integration/results.go

@@ -211,13 +211,13 @@ func assertCollectionDescriptions(
 
 		if expected.Indexes != nil || len(actual.Indexes) != 0 {
 			// Dont bother asserting this if the expected is nil and the actual is nil/empty.
-			// This is to say each test action from having to bother declaring an empty slice (if there are no indexes)
+			// This is to save each test action from having to bother declaring an empty slice (if there are no indexes)
 			require.Equal(s.t, expected.Indexes, actual.Indexes)
 		}
 
 		if expected.Sources != nil || len(actual.Sources) != 0 {
 			// Dont bother asserting this if the expected is nil and the actual is nil/empty.
-			// This is to say each test action from having to bother declaring an empty slice (if there are no sources)
+			// This is to save each test action from having to bother declaring an empty slice (if there are no sources)
 			require.Equal(s.t, expected.Sources, actual.Sources)
 		}
 

tests/integration/schema/one_many_test.go

@@ -0,0 +1,85 @@
+// Copyright 2024 Democratized Data Foundation
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+package schema
+
+import (
+	"testing"
+
+	"github.com/sourcenetwork/immutable"
+
+	"github.com/sourcenetwork/defradb/client"
+	testUtils "github.com/sourcenetwork/defradb/tests/integration"
+)
+
+func TestSchemaOneMany_Primary(t *testing.T) {
+	test := testUtils.TestCase{
+		Actions: []any{
+			testUtils.SchemaUpdate{
+				Schema: `
+					type User {
+						name: String
+						dogs: [Dog]
+					}
+					type Dog {
+						name: String
+						owner: User @primary
+					}
+				`,
+				ExpectedResults: []client.CollectionDescription{
+					{
+						Name: immutable.Some("User"),
+						Fields: []client.CollectionFieldDescription{
+							{
+								Name: "_docID",
+							},
+							{
+								Name:         "dogs",
+								ID:           1,
+								Kind:         immutable.Some[client.FieldKind](client.ObjectArrayKind("Dog")),
+								RelationName: immutable.Some("dog_user"),
+							},
+							{
+								Name: "name",
+								ID:   2,
+							},
+						},
+					},
+					{
+						Name: immutable.Some("Dog"),
+						Fields: []client.CollectionFieldDescription{
+							{
+								Name: "_docID",
+							},
+							{
+								Name: "name",
+								ID:   1,
+							},
+							{
+								Name:         "owner",
+								ID:           2,
+								Kind:         immutable.Some[client.FieldKind](client.ObjectKind("User")),
+								RelationName: immutable.Some("dog_user"),
+							},
+							{
+								Name:         "owner_id",
+								ID:           3,
+								Kind:         immutable.Some[client.FieldKind](client.ScalarKind(client.FieldKind_DocID)),
+								RelationName: immutable.Some("dog_user"),
+							},
+						},
+					},
+				},
+			},
+		},
+	}
+
+	testUtils.ExecuteTestCase(t, test)
+}