Only (re) add primary field if it hasnt already been created

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/schema/one_many_test.go

@@ -13,6 +13,9 @@ package schema
 import (
 	"testing"
 
+	"github.com/sourcenetwork/immutable"
+
+	"github.com/sourcenetwork/defradb/client"
 	testUtils "github.com/sourcenetwork/defradb/tests/integration"
 )
 
@@ -30,7 +33,50 @@ func TestSchemaOneMany_Primary(t *testing.T) {
 						owner: User @primary
 					}
 				`,
-				ExpectedError: "duplicate field. Name: owner",
+				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"),
+							},
+						},
+					},
+				},
 			},
 		},
 	}