Fix(GraphQL): This PR add schema cleaning in GraphQL. (#6427)

Fixes GRAPHQL-572

This PR adds schema cleaning in GraphQL which will remove empty links and types from generated GraphQL schema recursively.

graphql/admin/schema.go

@@ -20,8 +20,8 @@ import (
 	"bytes"
 	"context"
 	"encoding/json"
-
 	dgoapi "github.com/dgraph-io/dgo/v200/protos/api"
+
 	"github.com/dgraph-io/dgraph/edgraph"
 	"github.com/dgraph-io/dgraph/gql"
 	"github.com/dgraph-io/dgraph/graphql/resolve"

graphql/schema/gqlschema.go

@@ -577,11 +577,88 @@ func completeSchema(sch *ast.Schema, definitions []string) {
 	}
 }
 
+func cleanupInput(sch *ast.Schema, def *ast.Definition, seen map[string]bool) {
+	// seen helps us avoid cycles
+	if def == nil || seen[def.Name] {
+		return
+	}
+
+	i := 0
+	// recursively walk over fields for an input type and delete those which are themselves empty.
+	for _, f := range def.Fields {
+		nt := f.Type.Name()
+		enum := sch.Types[nt] != nil && sch.Types[nt].Kind == "ENUM"
+		// Lets skip scalar types and enums.
+		if _, ok := scalarToDgraph[nt]; ok || enum {
+			def.Fields[i] = f
+			i++
+			continue
+		}
+
+		seen[def.Name] = true
+		cleanupInput(sch, sch.Types[nt], seen)
+		seen[def.Name] = false
+
+		// If after calling cleanup on an input type, it got deleted then it doesn't need to be
+		// in the fields for this type anymore.
+		if sch.Types[nt] == nil {
+			continue
+		}
+		def.Fields[i] = f
+		i++
+	}
+	def.Fields = def.Fields[:i]
+
+	if len(def.Fields) == 0 {
+		delete(sch.Types, def.Name)
+	}
+}
+
+func cleanSchema(sch *ast.Schema) {
+	// Let's go over inputs of the type TRef, TPatch and AddTInput and delete the ones which
+	// don't have field inside them.
+	for k := range sch.Types {
+		if strings.HasSuffix(k, "Ref") || strings.HasSuffix(k, "Patch") ||
+			(strings.HasPrefix(k, "Add") && strings.HasSuffix(k, "Input")) {
+			cleanupInput(sch, sch.Types[k], map[string]bool{})
+		}
+	}
+
+	// Let's go over mutations and cleanup those which don't have AddTInput defined in the schema
+	// anymore.
+	i := 0 // helps us overwrite the array with valid entries.
+	for _, field := range sch.Mutation.Fields {
+		custom := field.Directives.ForName("custom")
+		// We would only modify add type queries.
+		if custom != nil || !strings.HasPrefix(field.Name, "add") {
+			sch.Mutation.Fields[i] = field
+			i++
+			continue
+		}
+
+		// addT type mutations have an input which is AddTInput so if that doesn't exist anymore,
+		// we can delete the AddTPayload and also skip this mutation.
+		typ := field.Name[3:]
+		input := sch.Types["Add"+typ+"Input"]
+		if input == nil {
+			delete(sch.Types, "Add"+typ+"Payload")
+			continue
+		}
+		sch.Mutation.Fields[i] = field
+		i++
+
+	}
+	sch.Mutation.Fields = sch.Mutation.Fields[:i]
+}
+
 func addInputType(schema *ast.Schema, defn *ast.Definition) {
-	schema.Types["Add"+defn.Name+"Input"] = &ast.Definition{
-		Kind:   ast.InputObject,
-		Name:   "Add" + defn.Name + "Input",
-		Fields: getFieldsWithoutIDType(schema, defn),
+	field := getFieldsWithoutIDType(schema, defn)
+	if len(field) != 0 {
+		schema.Types["Add"+defn.Name+"Input"] = &ast.Definition{
+			Kind:   ast.InputObject,
+			Name:   "Add" + defn.Name + "Input",
+			Fields: field,
+		}
 	}
 }
 
@@ -604,10 +681,12 @@ func addReferenceType(schema *ast.Schema, defn *ast.Definition) {
 		}
 	}
 
-	schema.Types[defn.Name+"Ref"] = &ast.Definition{
-		Kind:   ast.InputObject,
-		Name:   defn.Name + "Ref",
-		Fields: flds,
+	if len(flds) != 0 {
+		schema.Types[defn.Name+"Ref"] = &ast.Definition{
+			Kind:   ast.InputObject,
+			Name:   defn.Name + "Ref",
+			Fields: flds,
+		}
 	}
 }
 
@@ -1040,11 +1119,12 @@ func addAddPayloadType(schema *ast.Schema, defn *ast.Definition) {
 	addFilterArgument(schema, qry)
 	addOrderArgument(schema, qry)
 	addPaginationArguments(qry)
-
-	schema.Types["Add"+defn.Name+"Payload"] = &ast.Definition{
-		Kind:   ast.Object,
-		Name:   "Add" + defn.Name + "Payload",
-		Fields: []*ast.FieldDefinition{qry, numUids},
+	if schema.Types["Add"+defn.Name+"Input"] != nil {
+		schema.Types["Add"+defn.Name+"Payload"] = &ast.Definition{
+			Kind:   ast.Object,
+			Name:   "Add" + defn.Name + "Payload",
+			Fields: []*ast.FieldDefinition{qry, numUids},
+		}
 	}
 }
 
@@ -1235,6 +1315,7 @@ func addAddMutation(schema *ast.Schema, defn *ast.Definition) {
 		},
 	}
 	schema.Mutation.Fields = append(schema.Mutation.Fields, add)
+
 }
 
 func addUpdateMutation(schema *ast.Schema, defn *ast.Definition) {
@@ -1285,6 +1366,9 @@ func addDeleteMutation(schema *ast.Schema, defn *ast.Definition) {
 }
 
 func addMutations(schema *ast.Schema, defn *ast.Definition) {
+	if schema.Types["Add"+defn.Name+"Input"] == nil {
+		return
+	}
 	addAddMutation(schema, defn)
 	addUpdateMutation(schema, defn)
 	addDeleteMutation(schema, defn)
@@ -1385,7 +1469,6 @@ func getFieldsWithoutIDType(schema *ast.Schema, defn *ast.Definition) ast.FieldL
 			(!hasID(schema.Types[fld.Type.Name()]) && !hasXID(schema.Types[fld.Type.Name()])) {
 			continue
 		}
-
 		fldList = append(fldList, createField(schema, fld))
 	}
 

graphql/schema/schemagen.go

@@ -214,6 +214,7 @@ func NewHandler(input string, validateOnly bool) (Handler, error) {
 	headers := getAllowedHeaders(sch, defns, authHeader)
 	dgSchema := genDgSchema(sch, typesToComplete)
 	completeSchema(sch, typesToComplete)
+	cleanSchema(sch)
 
 	if len(sch.Query.Fields) == 0 && len(sch.Mutation.Fields) == 0 {
 		return nil, gqlerror.Errorf("No query or mutation found in the generated schema")

graphql/schema/schemagen_test.go

@@ -87,7 +87,6 @@ func TestSchemaString(t *testing.T) {
 
 			_, err = FromString(newSchemaStr)
 			require.NoError(t, err)
-
 			outputFileName := outputDir + testFile.Name()
 			str2, err := ioutil.ReadFile(outputFileName)
 			require.NoError(t, err)

graphql/schema/testdata/schemagen/input/filter-cleanSchema-all-empty.graphql

@@ -0,0 +1,12 @@
+type X {
+    name: [Y]
+    f1: [Y] @dgraph(pred: "f1")
+}
+
+type Y {
+    f1: [X] @dgraph(pred: "~f1")
+}
+
+type Z {
+    add:[X]
+}

graphql/schema/testdata/schemagen/input/filter-cleanSchema-circular.graphql

@@ -0,0 +1,14 @@
+type X{
+	f1: [Y] @dgraph(pred: "f1")
+	f3: [Z] @dgraph(pred: "~f3")
+}
+
+type Y{
+	f1: [X] @dgraph(pred: "~f1")
+	f2: [Z] @dgraph(pred: "f2")
+}
+
+type Z{
+	f2: [Y] @dgraph(pred: "~f2")
+	f3: [X] @dgraph(pred: "f3")
+}

graphql/schema/testdata/schemagen/input/filter-cleanSchema-custom-mutation.graphql

@@ -0,0 +1,16 @@
+type User {
+	id: ID!
+	name: String!
+}
+
+input UserInput {
+	name: String!
+}
+
+type Mutation {
+	addMyFavouriteUsers(input: [UserInput!]!): [User] @custom(http: {
+		url: "http://my-api.com",
+		method: "POST",
+		body: "{ data: $input }"
+	})
+}

graphql/schema/testdata/schemagen/input/filter-cleanSchema-directLink.graphql

@@ -0,0 +1,14 @@
+type X {
+    f1: [Y] @dgraph(pred: "f1")
+    name: String
+    id: ID
+}
+
+type Y {
+    f2: [Z] @dgraph(pred: "~f2")
+    f1: [X] @dgraph(pred: "~f1")
+}
+
+type Z {
+    f2: [Y] @dgraph(pred: "f2")
+}

graphql/schema/testdata/schemagen/input/hasInverse-with-interface-having-directive.graphql

@@ -1,7 +1,7 @@
 type Author {
   id: ID!
   name: String! @search(by: [hash])
-  posts: [Post] 
+  posts: [Post]
 }
 
 interface Post {
@@ -12,7 +12,7 @@ interface Post {
 }
 
 type Question implements Post {
-  answered: Boolean 
+  answered: Boolean
 }
 
 type Answer implements Post {