feat(graphql): adds @default directive for setting default field values at create and update

graphql/e2e/schema/apollo_service_response.graphql

@@ -117,6 +117,10 @@ input CustomHTTP {
 	skipIntrospection: Boolean
 }
 
+input DgraphDefault {
+	value: String
+}
+
 type Point {
 	longitude: Float!
 	latitude: Float!
@@ -199,6 +203,7 @@ directive @hasInverse(field: String!) on FIELD_DEFINITION
 directive @search(by: [DgraphIndex!]) on FIELD_DEFINITION
 directive @dgraph(type: String, pred: String) on OBJECT | INTERFACE | FIELD_DEFINITION
 directive @id(interface: Boolean) on FIELD_DEFINITION
+directive @default(add: DgraphDefault, update: DgraphDefault) on FIELD_DEFINITION
 directive @withSubscription on OBJECT | INTERFACE | FIELD_DEFINITION
 directive @secret(field: String!, pred: String) on OBJECT | INTERFACE
 directive @remote on OBJECT | INTERFACE | UNION | INPUT_OBJECT | ENUM

graphql/e2e/schema/generatedSchema.graphql

@@ -98,6 +98,10 @@ input CustomHTTP {
 	skipIntrospection: Boolean
 }
 
+input DgraphDefault {
+	value: String
+}
+
 type Point {
 	longitude: Float!
 	latitude: Float!
@@ -180,6 +184,7 @@ directive @hasInverse(field: String!) on FIELD_DEFINITION
 directive @search(by: [DgraphIndex!]) on FIELD_DEFINITION
 directive @dgraph(type: String, pred: String) on OBJECT | INTERFACE | FIELD_DEFINITION
 directive @id(interface: Boolean) on FIELD_DEFINITION
+directive @default(add: DgraphDefault, update: DgraphDefault) on FIELD_DEFINITION
 directive @withSubscription on OBJECT | INTERFACE | FIELD_DEFINITION
 directive @secret(field: String!, pred: String) on OBJECT | INTERFACE
 directive @auth(

graphql/resolve/add_mutation_test.yaml

@@ -5504,3 +5504,160 @@
          implementing types of same interfaces: T1 and T2"
     }
 
+-
+  name: "Add mutation with @default directive"
+  gqlmutation: |
+    mutation($input: [AddBookingInput!]!) {
+      addBooking(input: $input) {
+        booking {
+          name
+          created
+          updated
+        }
+      }
+    }
+  gqlvariables: |
+    {
+      "input": [
+        {
+          "name": "Holiday to Bermuda"
+        }
+      ]
+    }
+  explanation: "As booking has @default fields and is being added, these should be set to the default add value"
+  dgmutations:
+    - setjson: |
+        {
+            "Booking.created": "2000-01-01T00:00:00.00Z",
+            "Booking.active": "false",
+            "Booking.count": "1",
+            "Booking.hotel": "add",
+            "Booking.length": "1.1",
+            "Booking.status": "ACTIVE",
+            "Booking.name": "Holiday to Bermuda",
+            "Booking.updated": "2000-01-01T00:00:00.00Z",
+            "dgraph.type": [
+                    "Booking"
+                ],
+            "uid":"_:Booking_1"
+        }
+
+-
+  name: "Add mutation with @default directive uses provided values"
+  gqlmutation: |
+    mutation($input: [AddBookingInput!]!) {
+      addBooking(input: $input) {
+        booking {
+          name
+          created
+          updated
+        }
+      }
+    }
+  gqlvariables: |
+    {
+      "input": [
+        {
+          "name": "Holiday to Bermuda",
+          "created": "2022-10-12T07:20:50.52Z",
+          "updated": "2023-10-12T07:20:50.52Z",
+          "active": false,
+          "length": 12.3,
+          "status": "INACTIVE",
+          "hotel": "provided"
+        }
+      ]
+    }
+  explanation: "Fields with @default(add) should use input values if provided (note that count is still using default)"
+  dgmutations:
+    - setjson: |
+        {
+            "Booking.name": "Holiday to Bermuda",
+            "Booking.created": "2022-10-12T07:20:50.52Z",
+            "Booking.updated": "2023-10-12T07:20:50.52Z",
+            "Booking.active": false,
+            "Booking.count": "1",
+            "Booking.hotel": "provided",
+            "Booking.length": 12.3,
+            "Booking.status": "INACTIVE",
+            "dgraph.type": [
+                    "Booking"
+                ],
+            "uid":"_:Booking_1"
+        }
+
+-
+  name: "Upsert mutation with @default directives where only one of the nodes exists"
+  explanation: "Booking1 should only have updated timestamp as it exists, Booking2 should have created and updated timestamps"
+  gqlmutation: |
+    mutation addBookingXID($input: [AddBookingXIDInput!]!) {
+      addBookingXID(input: $input, upsert: true) {
+        bookingXID {
+          name
+        }
+      }
+    }
+  gqlvariables: |
+    { "input":
+      [
+        {
+          "id": "Booking1",
+          "name": "Trip to Bermuda"
+        },
+        {
+          "id": "Booking2",
+          "name": "Trip to Antigua"
+        }
+      ]
+    }
+  dgquery: |-
+    query {
+      BookingXID_1(func: eq(BookingXID.id, "Booking1")) {
+        uid
+        dgraph.type
+      }
+      BookingXID_2(func: eq(BookingXID.id, "Booking2")) {
+        uid
+        dgraph.type
+      }
+    }
+  qnametouid: |-
+    {
+      "BookingXID_1": "0x11"
+    }
+  dgquerysec: |-
+    query {
+      BookingXID_1 as BookingXID_1(func: uid(0x11)) @filter(type(BookingXID)) {
+        uid
+      }
+    }
+  dgmutations:
+    - setjson: |
+        {
+          "uid" : "uid(BookingXID_1)",
+          "BookingXID.id": "Booking1",
+          "BookingXID.name": "Trip to Bermuda",
+          "BookingXID.updated": "2000-01-01T00:00:00.00Z",
+          "BookingXID.active": "true",
+          "BookingXID.count": "2",
+          "BookingXID.length": "1.2",
+          "BookingXID.status": "INACTIVE",
+          "BookingXID.hotel": "update"
+        }
+      cond: "@if(gt(len(BookingXID_1), 0))"
+    - setjson: |
+        {
+          "uid": "_:BookingXID_2",
+          "BookingXID.id": "Booking2",
+          "BookingXID.name": "Trip to Antigua",
+          "BookingXID.created": "2000-01-01T00:00:00.00Z",
+          "BookingXID.updated": "2000-01-01T00:00:00.00Z",
+          "BookingXID.active": "false",
+          "BookingXID.count": "1",
+          "BookingXID.length": "1.1",
+          "BookingXID.status": "ACTIVE",
+          "BookingXID.hotel": "add",
+          "dgraph.type": [
+            "BookingXID"
+          ]
+        }

graphql/resolve/mutation_rewriter.go

@@ -1598,6 +1598,8 @@ func rewriteObject(
 		}
 	}
 
+	action := "update"
+
 	// This is not an XID reference. This is also not a UID reference.
 	// This is definitely a new node.
 	// Create new node
@@ -1646,6 +1648,19 @@ func rewriteObject(
 		// "_:Project2" . myUID will store the variable generated to reference this node.
 		newObj["dgraph.type"] = dgraphTypes
 		newObj["uid"] = myUID
+		action = "add"
+	}
+
+	// Now we know whether this is a new node or not, we can set @default(add/update) fields
+	for _, field := range typ.Fields() {
+		var pred = field.DgraphPredicate()
+		if newObj[pred] != nil {
+			continue
+		}
+		var value = field.GetDefaultValue(action)
+		if value != nil {
+			newObj[pred] = value
+		}
 	}
 
 	// Add Inverse Link if necessary

graphql/resolve/schema.graphql

@@ -175,6 +175,32 @@ type Student implements People {
     taughtBy: [Teacher] @hasInverse(field: "teaches")
 }
 
+# For testing default values
+type Booking {
+    id: ID!
+    name: String!
+    created: DateTime! @default(add: {value: "$now"})
+    updated: DateTime! @default(add: {value: "$now"}, update: {value: "$now"})
+    count: Int! @default(add: {value: "1"}, update: {value: "2"})
+    length: Float! @default(add: {value: "1.1"}, update: {value: "1.2"})
+    hotel: String! @default(add: {value: "add"}, update: {value: "update"})
+    active: Boolean! @default(add: {value: "false"}, update: {value: "true"})
+    status: Status! @default(add: {value: "ACTIVE"}, update: {value: "INACTIVE"})
+}
+
+# For testing default values with upserts
+type BookingXID {
+    id: String! @id
+    name: String!
+    created: DateTime! @default(add: {value: "$now"})
+    updated: DateTime! @default(add: {value: "$now"}, update: {value: "$now"})
+    count: Int! @default(add: {value: "1"}, update: {value: "2"})
+    length: Float! @default(add: {value: "1.1"}, update: {value: "1.2"})
+    hotel: String! @default(add: {value: "add"}, update: {value: "update"})
+    active: Boolean! @default(add: {value: "false"}, update: {value: "true"})
+    status: Status! @default(add: {value: "ACTIVE"}, update: {value: "INACTIVE"})
+}
+
 type Comment {
     id: ID!
     author: String!

graphql/resolve/update_mutation_test.yaml

@@ -2405,3 +2405,88 @@
          "uid": "uid(x)"
        }
     cond: "@if(gt(len(x), 0))"
+
+-
+  name: "Update with @default directive"
+  gqlmutation: |
+    mutation updateBooking($patch: UpdateBookingInput!) {
+      updateBooking(input: $patch) {
+        booking {
+          id
+        }
+      }
+    }
+  gqlvariables: |
+    { "patch":
+      { "filter": {
+          "id": ["0x123", "0x124"]
+        },
+        "set": {
+          "name": "Flight to Antigua"
+        }
+      }
+    }
+  explanation: "The update patch should include default values on the fields with the @default(update:) directive"
+  dgquerysec: |-
+    query {
+      x as updateBooking(func: uid(0x123, 0x124)) @filter(type(Booking)) {
+        uid
+      }
+    }
+  dgmutations:
+    - setjson: |
+        { "uid" : "uid(x)",
+          "Booking.name": "Flight to Antigua",
+          "Booking.updated": "2000-01-01T00:00:00.00Z",
+          "Booking.active": "true",
+          "Booking.count": "2",
+          "Booking.length": "1.2",
+          "Booking.status": "INACTIVE",
+          "Booking.hotel": "update"
+        }
+      cond: "@if(gt(len(x), 0))"
+
+-
+  name: "Update with @default directive uses provided values"
+  gqlmutation: |
+    mutation updateBooking($patch: UpdateBookingInput!) {
+      updateBooking(input: $patch) {
+        booking {
+          id
+        }
+      }
+    }
+  gqlvariables: |
+    { "patch":
+      { "filter": {
+          "id": ["0x123", "0x124"]
+        },
+        "set": {
+          "name": "Flight to Antigua",
+          "updated": "2022-10-12T07:20:50.52Z",
+          "active": false,
+          "length": 12.3,
+          "status": "ACTIVE",
+          "hotel": "provided"
+        }
+      }
+    }
+  explanation: "Fields with @default(update) should use input values if provided (note that count is still using default)"
+  dgquerysec: |-
+    query {
+      x as updateBooking(func: uid(0x123, 0x124)) @filter(type(Booking)) {
+        uid
+      }
+    }
+  dgmutations:
+    - setjson: |
+        { "uid" : "uid(x)",
+          "Booking.name": "Flight to Antigua",
+          "Booking.updated": "2022-10-12T07:20:50.52Z",
+          "Booking.active": false,
+          "Booking.count": "2",
+          "Booking.length": 12.3,
+          "Booking.status": "ACTIVE",
+          "Booking.hotel": "provided"
+        }
+      cond: "@if(gt(len(x), 0))"