add test for recursive

libs/jsonschema/from_type.go

@@ -35,6 +35,8 @@ type constructor struct {
 	// Example key: github.com/databricks/databricks-sdk-go/service/jobs.JobSettings
 	definitions map[string]Schema
 
+	seen map[string]struct{}
+
 	// Transformation function to apply after generating a node in the schema.
 	fn func(s Schema) Schema
 }
@@ -74,10 +76,11 @@ func (c *constructor) nestedDefinitions() any {
 func FromType(typ reflect.Type, fn func(s Schema) Schema) (Schema, error) {
 	c := constructor{
 		definitions: make(map[string]Schema),
+		seen:        make(map[string]struct{}),
 		fn:          fn,
 	}
 
-	_, err := c.walk(typ)
+	err := c.walk(typ)
 	if err != nil {
 		return InvalidSchema, err
 	}
@@ -90,6 +93,11 @@ func FromType(typ reflect.Type, fn func(s Schema) Schema) (Schema, error) {
 }
 
 func typePath(typ reflect.Type) string {
+	// Pointers have a typ.Name() of "". Dereference them to get the underlying type.
+	for typ.Kind() == reflect.Ptr {
+		typ = typ.Elem()
+	}
+
 	// typ.Name() resolves to "" for any type.
 	if typ.Kind() == reflect.Interface {
 		return "interface"
@@ -105,7 +113,7 @@ func typePath(typ reflect.Type) string {
 
 // TODO: would a worked based model fit better here? Is this internal API not
 // the right fit?
-func (c *constructor) walk(typ reflect.Type) (string, error) {
+func (c *constructor) walk(typ reflect.Type) error {
 	// Dereference pointers if necessary.
 	for typ.Kind() == reflect.Ptr {
 		typ = typ.Elem()
@@ -113,9 +121,14 @@ func (c *constructor) walk(typ reflect.Type) (string, error) {
 
 	typPath := typePath(typ)
 
-	// Return value directly if it's already been processed.
+	// Keep track of seen types to avoid infinite recursion.
+	if _, ok := c.seen[typPath]; !ok {
+		c.seen[typPath] = struct{}{}
+	}
+
+	// Return early directly if it's already been processed.
 	if _, ok := c.definitions[typPath]; ok {
-		return typPath, nil
+		return nil
 	}
 
 	var s Schema
@@ -144,10 +157,10 @@ func (c *constructor) walk(typ reflect.Type) (string, error) {
 		// set to null and disallowed in the schema.
 		s = Schema{Type: NullType}
 	default:
-		return "", fmt.Errorf("unsupported type: %s", typ.Kind())
+		return fmt.Errorf("unsupported type: %s", typ.Kind())
 	}
 	if err != nil {
-		return "", err
+		return err
 	}
 
 	if c.fn != nil {
@@ -158,7 +171,7 @@ func (c *constructor) walk(typ reflect.Type) (string, error) {
 	// TODO: Apply transformation at the end, to all definitions instead of
 	// during recursive traversal?
 	c.definitions[typPath] = s
-	return typPath, nil
+	return nil
 }
 
 // This function returns all member fields of the provided type.
@@ -193,6 +206,7 @@ func getStructFields(typ reflect.Type) []reflect.StructField {
 	return fields
 }
 
+// TODO: get rid of the errors here and panic instead?
 func (c *constructor) fromTypeStruct(typ reflect.Type) (Schema, error) {
 	if typ.Kind() != reflect.Struct {
 		return InvalidSchema, fmt.Errorf("expected struct, got %s", typ.Kind())
@@ -233,12 +247,16 @@ func (c *constructor) fromTypeStruct(typ reflect.Type) (Schema, error) {
 			res.Required = append(res.Required, jsonTags[0])
 		}
 
+		typPath := typePath(structField.Type)
+		// Only walk if the type has not been seen yet.
+		if _, ok := c.seen[typPath]; !ok {
 			// Trigger call to fromType, to recursively generate definitions for
 			// the struct field.
-		typPath, err := c.walk(structField.Type)
+			err := c.walk(structField.Type)
 			if err != nil {
 				return InvalidSchema, err
 			}
+		}
 
 		refPath := path.Join("#/$defs", typPath)
 		// For non-built-in types, refer to the definition.
@@ -261,12 +279,16 @@ func (c *constructor) fromTypeSlice(typ reflect.Type) (Schema, error) {
 		Type: ArrayType,
 	}
 
+	typPath := typePath(typ.Elem())
+	// Only walk if the type has not been seen yet.
+	if _, ok := c.seen[typPath]; !ok {
 		// Trigger call to fromType, to recursively generate definitions for
 		// the slice element.
-	typPath, err := c.walk(typ.Elem())
+		err := c.walk(typ.Elem())
 		if err != nil {
 			return InvalidSchema, err
 		}
+	}
 
 	refPath := path.Join("#/$defs", typPath)
 
@@ -290,12 +312,16 @@ func (c *constructor) fromTypeMap(typ reflect.Type) (Schema, error) {
 		Type: ObjectType,
 	}
 
+	typPath := typePath(typ.Elem())
+	// Only walk if the type has not been seen yet.
+	if _, ok := c.seen[typPath]; !ok {
 		// Trigger call to fromType, to recursively generate definitions for
 		// the map value.
-	typPath, err := c.walk(typ.Elem())
+		err := c.walk(typ.Elem())
 		if err != nil {
 			return InvalidSchema, err
 		}
+	}
 
 	refPath := path.Join("#/$defs", typPath)
 

libs/jsonschema/from_type_test.go

@@ -1,9 +1,11 @@
 package jsonschema
 
 import (
+	"encoding/json"
 	"reflect"
 	"testing"
 
+	"github.com/databricks/cli/libs/jsonschema/test_types"
 	"github.com/stretchr/testify/assert"
 )
 
@@ -259,3 +261,65 @@ func TestFromTypeNested(t *testing.T) {
 		})
 	}
 }
+
+// TODO: Call out in the PR description that recursive Go types are supported.
+func TestFromTypeRecursive(t *testing.T) {
+	fooRef := "#/$defs/github.com/databricks/cli/libs/jsonschema/test_types.Foo"
+	barRef := "#/$defs/github.com/databricks/cli/libs/jsonschema/test_types.Bar"
+
+	expected := Schema{
+		Type: "object",
+		Definitions: map[string]any{
+			"github.com": map[string]any{
+				"databricks": map[string]any{
+					"cli": map[string]any{
+						"libs": map[string]any{
+							"jsonschema": map[string]any{
+								"test_types.Bar": Schema{
+									Type: "object",
+									Properties: map[string]*Schema{
+										"foo": {
+											Reference: &fooRef,
+										},
+									},
+									AdditionalProperties: false,
+									Required:             []string{},
+								},
+								"test_types.Foo": Schema{
+									Type: "object",
+									Properties: map[string]*Schema{
+										"bar": {
+											Reference: &barRef,
+										},
+									},
+									AdditionalProperties: false,
+									Required:             []string{},
+								},
+							},
+						},
+					},
+				},
+			},
+		},
+		Properties: map[string]*Schema{
+			"foo": {
+				Reference: &fooRef,
+			},
+		},
+		AdditionalProperties: false,
+		Required:             []string{"foo"},
+	}
+
+	s, err := FromType(reflect.TypeOf(test_types.Outer{}), nil)
+	assert.NoError(t, err)
+	assert.Equal(t, expected, s)
+
+	jsonSchema, err := json.MarshalIndent(s, "		", "	")
+	assert.NoError(t, err)
+
+	expectedJson, err := json.MarshalIndent(expected, "		", "	")
+	assert.NoError(t, err)
+
+	t.Log("[DEBUG] actual: ", string(jsonSchema))
+	t.Log("[DEBUG] expected: ", string(expectedJson))
+}

libs/jsonschema/test_types/test_types.go

@@ -0,0 +1,15 @@
+package test_types
+
+// Recursive types cannot be defined inline without making them anonymous,
+// so we define them here instead.
+type Foo struct {
+	Bar *Bar `json:"bar,omitempty"`
+}
+
+type Bar struct {
+	Foo Foo `json:"foo,omitempty"`
+}
+
+type Outer struct {
+	Foo Foo `json:"foo"`
+}