Add Paved.MargeValue method

- Add "fieldpath/object" package that deals with runtime.Objects
- Move MergeOptions struct to package "apis/common/v1".

Signed-off-by: Alper Rifat Ulucinar <ulucinar@users.noreply.github.com>

apis/common/v1/merge.go

@@ -0,0 +1,47 @@
+/*
+Copyright 2021 The Crossplane Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package v1
+
+import (
+	"github.com/imdario/mergo"
+)
+
+// MergeOptions Specifies merge options on a field path
+type MergeOptions struct { // TODO(aru): add more options that control merging behavior
+	// Specifies that already existing values in a merged map should be preserved
+	// +optional
+	KeepMapValues *bool `json:"keepMapValues,omitempty"`
+	// Specifies that already existing elements in a merged slice should be preserved
+	// +optional
+	AppendSlice *bool `json:"appendSlice,omitempty"`
+}
+
+// MergoConfiguration the default behavior is to replace maps and slices
+func (mo *MergeOptions) MergoConfiguration() []func(*mergo.Config) {
+	config := []func(*mergo.Config){mergo.WithOverride}
+	if mo == nil {
+		return config
+	}
+
+	if mo.KeepMapValues != nil && *mo.KeepMapValues {
+		config = config[:0]
+	}
+	if mo.AppendSlice != nil && *mo.AppendSlice {
+		config = append(config, mergo.WithAppendSlice)
+	}
+	return config
+}

apis/common/v1/merge_test.go

@@ -0,0 +1,90 @@
+/*
+Copyright 2021 The Crossplane Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package v1
+
+import (
+	"reflect"
+	"runtime"
+	"sort"
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+	"github.com/imdario/mergo"
+)
+
+type mergoOptArr []func(*mergo.Config)
+
+func (arr mergoOptArr) names() []string {
+	names := make([]string, len(arr))
+	for i, opt := range arr {
+		names[i] = runtime.FuncForPC(reflect.ValueOf(opt).Pointer()).Name()
+	}
+	sort.Strings(names)
+	return names
+}
+
+func TestMergoConfiguration(t *testing.T) {
+	valTrue := true
+	tests := map[string]struct {
+		mo   *MergeOptions
+		want mergoOptArr
+	}{
+		"DefaultOptionsNil": {
+			want: mergoOptArr{
+				mergo.WithOverride,
+			},
+		},
+		"DefaultOptionsEmptyStruct": {
+			mo: &MergeOptions{},
+			want: mergoOptArr{
+				mergo.WithOverride,
+			},
+		},
+		"MapKeepOnly": {
+			mo: &MergeOptions{
+				KeepMapValues: &valTrue,
+			},
+			want: mergoOptArr{},
+		},
+		"AppendSliceOnly": {
+			mo: &MergeOptions{
+				AppendSlice: &valTrue,
+			},
+			want: mergoOptArr{
+				mergo.WithAppendSlice,
+				mergo.WithOverride,
+			},
+		},
+		"MapKeepAppendSlice": {
+			mo: &MergeOptions{
+				AppendSlice:   &valTrue,
+				KeepMapValues: &valTrue,
+			},
+			want: mergoOptArr{
+				mergo.WithAppendSlice,
+			},
+		},
+	}
+	for name, tc := range tests {
+		t.Run(name, func(t *testing.T) {
+			if diff := cmp.Diff(tc.want.names(), mergoOptArr(tc.mo.MergoConfiguration()).names()); diff != "" {
+				t.Errorf("\nmo.MergoConfiguration(): -want, +got:\n %s", diff)
+			}
+
+		})
+	}
+}

apis/common/v1/zz_generated.deepcopy.go

@@ -137,6 +137,31 @@ func (in *LocalSecretReference) DeepCopy() *LocalSecretReference {
 	return out
 }
 
+// DeepCopyInto is an autogenerated deepcopy function, copying the receiver, writing into out. in must be non-nil.
+func (in *MergeOptions) DeepCopyInto(out *MergeOptions) {
+	*out = *in
+	if in.KeepMapValues != nil {
+		in, out := &in.KeepMapValues, &out.KeepMapValues
+		*out = new(bool)
+		**out = **in
+	}
+	if in.AppendSlice != nil {
+		in, out := &in.AppendSlice, &out.AppendSlice
+		*out = new(bool)
+		**out = **in
+	}
+}
+
+// DeepCopy is an autogenerated deepcopy function, copying the receiver, creating a new MergeOptions.
+func (in *MergeOptions) DeepCopy() *MergeOptions {
+	if in == nil {
+		return nil
+	}
+	out := new(MergeOptions)
+	in.DeepCopyInto(out)
+	return out
+}
+
 // DeepCopyInto is an autogenerated deepcopy function, copying the receiver, writing into out. in must be non-nil.
 func (in *ProviderConfigStatus) DeepCopyInto(out *ProviderConfigStatus) {
 	*out = *in

pkg/fieldpath/merge.go

@@ -1,156 +0,0 @@
-/*
-Copyright 2021 The Crossplane Authors.
-
-Licensed under the Apache License, Version 2.0 (the "License");
-you may not use this file except in compliance with the License.
-You may obtain a copy of the License at
-
-    http://www.apache.org/licenses/LICENSE-2.0
-
-Unless required by applicable law or agreed to in writing, software
-distributed under the License is distributed on an "AS IS" BASIS,
-WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-See the License for the specific language governing permissions and
-limitations under the License.
-*/
-
-package fieldpath
-
-import (
-	"reflect"
-
-	"github.com/imdario/mergo"
-	"github.com/pkg/errors"
-	"k8s.io/apimachinery/pkg/runtime"
-)
-
-const (
-	errInvalidMerge = "failed to merge values"
-)
-
-// MergeOptions Specifies merge options on a field path
-type MergeOptions struct { // TODO(aru): add more options that control merging behavior
-	// Specifies that already existing values in a merged map should be preserved
-	KeepMapValues bool `json:"keepMapValues,omitempty"`
-	// Specifies that already existing elements in a merged slice should be preserved
-	AppendSlice bool `json:"appendSlice,omitempty"`
-}
-
-// MergoConfiguration the default behavior is to replace maps and slices
-func (mo *MergeOptions) MergoConfiguration() []func(*mergo.Config) {
-	config := []func(*mergo.Config){mergo.WithOverride}
-	if mo == nil {
-		return config
-	}
-
-	if mo.KeepMapValues {
-		config = config[:0]
-	}
-	if mo.AppendSlice {
-		config = append(config, mergo.WithAppendSlice)
-	}
-	return config
-}
-
-// ToPaved tries to convert a runtime.Object into a *Paved via
-// runtime.DefaultUnstructuredConverter if needed. Returns the paved if
-// the conversion is successful along with whether the
-// runtime.DefaultUnstructuredConverter has been employed during the
-// conversion.
-func ToPaved(o runtime.Object) (*Paved, bool, error) {
-	if u, ok := o.(interface{ UnstructuredContent() map[string]interface{} }); ok {
-		return Pave(u.UnstructuredContent()), false, nil
-	}
-
-	oMap, err := runtime.DefaultUnstructuredConverter.ToUnstructured(o)
-	if err != nil {
-		return nil, false, err
-	}
-	return Pave(oMap), true, nil
-}
-
-// PatchFieldValueToObject applies the value to the "to" object at the given
-// path with the given merge options, returning any errors as they occur.
-// If no merge options is supplied, then destination field is replaced
-// with the given value.
-func PatchFieldValueToObject(fieldPath string, value interface{}, to runtime.Object,
-	mergeOptions *MergeOptions) error {
-	paved, copied, err := ToPaved(to)
-	if err != nil {
-		return err
-	}
-	dst, err := paved.GetValue(fieldPath)
-	if IsNotFound(err) || mergeOptions == nil {
-		dst = nil
-	} else if err != nil {
-		return err
-	}
-
-	dst, err = merge(dst, value, mergeOptions)
-	if err != nil {
-		return err
-	}
-
-	if err := paved.SetValue(fieldPath, dst); err != nil {
-		return err
-	}
-
-	if copied {
-		return runtime.DefaultUnstructuredConverter.FromUnstructured(paved.object, to)
-	}
-	return nil
-}
-
-// MergePath merges the value at the given field path of the src object into
-// the dst object.
-func MergePath(fieldPath string, dst, src runtime.Object, mergeOptions *MergeOptions) error {
-	srcPaved, _, err := ToPaved(src)
-	if err != nil {
-		return err
-	}
-
-	val, err := srcPaved.GetValue(fieldPath)
-	// if src has no value at the specified path, then nothing to merge
-	if IsNotFound(err) || val == nil {
-		return nil
-	}
-	if err != nil {
-		return err
-	}
-
-	return PatchFieldValueToObject(fieldPath, val, dst, mergeOptions)
-}
-
-// MergeReplace merges the value at fieldPath from desired into
-// a copy of current and then replaces the value at fieldPath of
-// desired with the merged value. current object is not modified.
-func MergeReplace(fieldPath string, current, desired runtime.Object, mergeOptions *MergeOptions) error {
-	copyCurrent := current.DeepCopyObject()
-	if err := MergePath(fieldPath, copyCurrent, desired, mergeOptions); err != nil {
-		return err
-	}
-	// replace desired object's value at fieldPath with
-	// the computed (merged) current value at the same path
-	return MergePath(fieldPath, desired, copyCurrent, nil)
-}
-
-// merges the given src onto the given dst.
-// If a nil merge options is supplied, the default behavior is MergeOptions'
-// default behavior. If dst or src is nil, src is returned
-// (i.e., dst replaced by src).
-func merge(dst, src interface{}, mergeOptions *MergeOptions) (interface{}, error) {
-	if dst == nil || src == nil {
-		return src, nil // no merge, replace
-	}
-
-	m, ok := dst.(map[string]interface{})
-	if reflect.TypeOf(src).Kind() != reflect.Map || !ok {
-		return src, nil // not a map nor a struct, mergo cannot merge
-	}
-
-	// use merge semantics with the configured merge options to obtain the target dst value
-	if err := mergo.Merge(&m, src, mergeOptions.MergoConfiguration()...); err != nil {
-		return nil, errors.Wrap(err, errInvalidMerge)
-	}
-	return m, nil
-}

pkg/fieldpath/object/object.go

@@ -0,0 +1,94 @@
+/*
+Copyright 2021 The Crossplane Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package object
+
+import (
+	"k8s.io/apimachinery/pkg/runtime"
+
+	v1 "github.com/crossplane/crossplane-runtime/apis/common/v1"
+	"github.com/crossplane/crossplane-runtime/pkg/fieldpath"
+)
+
+// ToPaved tries to convert a runtime.Object into a *Paved via
+// runtime.DefaultUnstructuredConverter if needed. Returns the paved if
+// the conversion is successful along with whether the
+// runtime.DefaultUnstructuredConverter has been employed during the
+// conversion.
+func ToPaved(o runtime.Object) (*fieldpath.Paved, bool, error) {
+	if u, ok := o.(interface{ UnstructuredContent() map[string]interface{} }); ok {
+		return fieldpath.Pave(u.UnstructuredContent()), false, nil
+	}
+
+	oMap, err := runtime.DefaultUnstructuredConverter.ToUnstructured(o)
+	if err != nil {
+		return nil, false, err
+	}
+	return fieldpath.Pave(oMap), true, nil
+}
+
+// PatchFieldValueToObject applies the value to the "to" object at the given
+// path with the given merge options, returning any errors as they occur.
+// If no merge options is supplied, then destination field is replaced
+// with the given value.
+func PatchFieldValueToObject(fieldPath string, value interface{}, to runtime.Object, mo *v1.MergeOptions) error {
+	paved, copied, err := ToPaved(to)
+	if err != nil {
+		return err
+	}
+
+	if err := paved.MergeValue(fieldPath, value, mo); err != nil {
+		return err
+	}
+
+	if copied {
+		return runtime.DefaultUnstructuredConverter.FromUnstructured(paved.UnstructuredContent(), to)
+	}
+	return nil
+}
+
+// MergePath merges the value at the given field path of the src object into
+// the dst object.
+func MergePath(path string, dst, src runtime.Object, mergeOptions *v1.MergeOptions) error {
+	srcPaved, _, err := ToPaved(src)
+	if err != nil {
+		return err
+	}
+
+	val, err := srcPaved.GetValue(path)
+	// if src has no value at the specified path, then nothing to merge
+	if fieldpath.IsNotFound(err) || val == nil {
+		return nil
+	}
+	if err != nil {
+		return err
+	}
+
+	return PatchFieldValueToObject(path, val, dst, mergeOptions)
+}
+
+// MergeReplace merges the value at path from dst into
+// a copy of src and then replaces the value at path of
+// dst with the merged value. src object is not modified.
+func MergeReplace(path string, src, dst runtime.Object, mo *v1.MergeOptions) error {
+	copySrc := src.DeepCopyObject()
+	if err := MergePath(path, copySrc, dst, mo); err != nil {
+		return err
+	}
+	// replace desired object's value at fieldPath with
+	// the computed (merged) current value at the same path
+	return MergePath(path, dst, copySrc, nil)
+}

pkg/fieldpath/object/object_test.go

@@ -14,86 +14,23 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-package fieldpath
+package object
 
 import (
 	"fmt"
 	"reflect"
-	"runtime"
-	"sort"
 	"testing"
 
 	"github.com/google/go-cmp/cmp"
-	"github.com/imdario/mergo"
-	v1 "k8s.io/api/core/v1"
+	corev1 "k8s.io/api/core/v1"
 	k8s "k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/runtime/schema"
 
+	v1 "github.com/crossplane/crossplane-runtime/apis/common/v1"
+	"github.com/crossplane/crossplane-runtime/pkg/fieldpath"
 	"github.com/crossplane/crossplane-runtime/pkg/test"
 )
 
-type mergoOptArr []func(*mergo.Config)
-
-func (arr mergoOptArr) names() []string {
-	names := make([]string, len(arr))
-	for i, opt := range arr {
-		names[i] = runtime.FuncForPC(reflect.ValueOf(opt).Pointer()).Name()
-	}
-	sort.Strings(names)
-	return names
-}
-
-func TestMergoConfiguration(t *testing.T) {
-	tests := map[string]struct {
-		mo   *MergeOptions
-		want mergoOptArr
-	}{
-		"DefaultOptionsNil": {
-			want: mergoOptArr{
-				mergo.WithOverride,
-			},
-		},
-		"DefaultOptionsEmptyStruct": {
-			mo: &MergeOptions{},
-			want: mergoOptArr{
-				mergo.WithOverride,
-			},
-		},
-		"MapKeepOnly": {
-			mo: &MergeOptions{
-				KeepMapValues: true,
-			},
-			want: mergoOptArr{},
-		},
-		"AppendSliceOnly": {
-			mo: &MergeOptions{
-				AppendSlice: true,
-			},
-			want: mergoOptArr{
-				mergo.WithAppendSlice,
-				mergo.WithOverride,
-			},
-		},
-		"MapKeepAppendSlice": {
-			mo: &MergeOptions{
-				AppendSlice:   true,
-				KeepMapValues: true,
-			},
-			want: mergoOptArr{
-				mergo.WithAppendSlice,
-			},
-		},
-	}
-	for name, tc := range tests {
-		t.Run(name, func(t *testing.T) {
-			if diff := cmp.Diff(tc.want.names(), mergoOptArr(tc.mo.MergoConfiguration()).names()); diff != "" {
-				t.Errorf("\nmo.MergoConfiguration(): -want, +got:\n %s", diff)
-			}
-
-		})
-	}
-}
-
 type objWithUnstructuredContent struct {
 	m map[string]interface{}
 }
@@ -110,7 +47,7 @@ func (o objWithUnstructuredContent) UnstructuredContent() map[string]interface{}
 	return o.m
 }
 
-func pavedComparer(p1, p2 Paved) bool {
+func pavedComparer(p1, p2 fieldpath.Paved) bool {
 	return reflect.DeepEqual(p1, p2)
 }
 
@@ -119,7 +56,7 @@ func TestToPaved(t *testing.T) {
 		o k8s.Object
 	}
 	type want struct {
-		paved  *Paved
+		paved  *fieldpath.Paved
 		copied bool
 		err    error
 	}
@@ -138,25 +75,25 @@ func TestToPaved(t *testing.T) {
 				},
 			},
 			want: want{
-				paved: &Paved{
-					object: map[string]interface{}{
+				paved: fieldpath.Pave(
+					map[string]interface{}{
 						"key": "val",
 					},
-				},
+				),
 			},
 		},
 		"NoUnstructuredContent": {
 			reason: "If object does not provide UnstructuredContent, unstructured converter will be used to pave it, with its contents being copied",
 			args: args{
-				o: &v1.ConfigMap{},
+				o: &corev1.ConfigMap{},
 			},
 			want: want{
 				copied: true,
-				paved: &Paved{
-					object: map[string]interface{}{
+				paved: fieldpath.Pave(
+					map[string]interface{}{
 						"metadata": map[string]interface{}{"creationTimestamp": nil},
 					},
-				},
+				),
 			},
 		},
 	}
@@ -180,6 +117,16 @@ func TestToPaved(t *testing.T) {
 	}
 }
 
+type strObject string
+
+func (strObject) GetObjectKind() schema.ObjectKind {
+	return nil
+}
+
+func (strObject) DeepCopyObject() k8s.Object {
+	return nil
+}
+
 type object struct {
 	P1 *p1
 }
@@ -201,16 +148,6 @@ func (object) DeepCopyObject() k8s.Object {
 	return nil
 }
 
-type strObject string
-
-func (strObject) GetObjectKind() schema.ObjectKind {
-	return nil
-}
-
-func (strObject) DeepCopyObject() k8s.Object {
-	return nil
-}
-
 var (
 	valStringDst   = "value-from-dst"
 	valStringSrc   = "value-from-src"
@@ -219,6 +156,7 @@ var (
 	valArrDst      = []string{valStringDst}
 	valArrSrc      = []string{valStringSrc}
 	valArrAppended = []string{valStringDst, valStringSrc}
+	valTrue        = true
 )
 
 func dstObject() *object {
@@ -252,7 +190,7 @@ func TestMergePath(t *testing.T) {
 		fieldPath    string
 		dst          k8s.Object
 		src          k8s.Object
-		mergeOptions *MergeOptions
+		mergeOptions *v1.MergeOptions
 	}
 	type want struct {
 		err error
@@ -290,8 +228,8 @@ func TestMergePath(t *testing.T) {
 				fieldPath: "p1.p2",
 				dst:       dstObject(),
 				src:       srcObject(),
-				mergeOptions: &MergeOptions{
-					KeepMapValues: true,
+				mergeOptions: &v1.MergeOptions{
+					KeepMapValues: &valTrue,
 				},
 			},
 			want: want{
@@ -313,9 +251,9 @@ func TestMergePath(t *testing.T) {
 				fieldPath: "p1.p2",
 				dst:       dstObject(),
 				src:       srcObject(),
-				mergeOptions: &MergeOptions{
-					KeepMapValues: true,
-					AppendSlice:   true,
+				mergeOptions: &v1.MergeOptions{
+					KeepMapValues: &valTrue,
+					AppendSlice:   &valTrue,
 				},
 			},
 			want: want{
@@ -367,9 +305,9 @@ func TestMergePath(t *testing.T) {
 						S: &valStringDst,
 					},
 				},
-				mergeOptions: &MergeOptions{
-					KeepMapValues: true,
-					AppendSlice:   true,
+				mergeOptions: &v1.MergeOptions{
+					KeepMapValues: &valTrue,
+					AppendSlice:   &valTrue,
 				},
 			},
 			want: want{
@@ -392,7 +330,7 @@ func TestMergePath(t *testing.T) {
 				src: strObject("src"),
 			},
 			want: want{
-				err: fmt.Errorf("ToUnstructured requires a non-nil pointer to an object, got fieldpath.strObject"),
+				err: fmt.Errorf("ToUnstructured requires a non-nil pointer to an object, got object.strObject"),
 			},
 		},
 		"ErrDstNotPaved": {
@@ -403,7 +341,7 @@ func TestMergePath(t *testing.T) {
 				src:       srcObject(),
 			},
 			want: want{
-				err: fmt.Errorf("ToUnstructured requires a non-nil pointer to an object, got fieldpath.strObject"),
+				err: fmt.Errorf("ToUnstructured requires a non-nil pointer to an object, got object.strObject"),
 			},
 		},
 	}
@@ -429,7 +367,7 @@ func TestMergeReplace(t *testing.T) {
 		fieldPath    string
 		current      k8s.Object
 		desired      k8s.Object
-		mergeOptions *MergeOptions
+		mergeOptions *v1.MergeOptions
 	}
 	type want struct {
 		current k8s.Object
@@ -443,28 +381,28 @@ func TestMergeReplace(t *testing.T) {
 		"HappyPath": {
 			args: args{
 				fieldPath: "data",
-				current: &v1.ConfigMap{
+				current: &corev1.ConfigMap{
 					Data: map[string]string{
 						"key1": "value-from-current",
 					},
 				},
-				desired: &v1.ConfigMap{
+				desired: &corev1.ConfigMap{
 					Data: map[string]string{
 						"key1": "value-from-desired",
 						"key2": "value-from-desired",
 					},
 				},
-				mergeOptions: &MergeOptions{
-					KeepMapValues: true,
+				mergeOptions: &v1.MergeOptions{
+					KeepMapValues: &valTrue,
 				},
 			},
 			want: want{
-				current: &v1.ConfigMap{
+				current: &corev1.ConfigMap{
 					Data: map[string]string{
 						"key1": "value-from-current",
 					},
 				},
-				desired: &v1.ConfigMap{
+				desired: &corev1.ConfigMap{
 					Data: map[string]string{
 						"key1": "value-from-current",
 						"key2": "value-from-desired",
@@ -479,7 +417,7 @@ func TestMergeReplace(t *testing.T) {
 				desired:   strObject("desired"),
 			},
 			want: want{
-				err: fmt.Errorf("ToUnstructured requires a non-nil pointer to an object, got fieldpath.strObject"),
+				err: fmt.Errorf("ToUnstructured requires a non-nil pointer to an object, got object.strObject"),
 			},
 		},
 	}

pkg/fieldpath/paved.go

@@ -17,9 +17,18 @@ limitations under the License.
 package fieldpath
 
 import (
+	"reflect"
+
+	"github.com/imdario/mergo"
 	"github.com/pkg/errors"
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/util/json"
+
+	xpv1 "github.com/crossplane/crossplane-runtime/apis/common/v1"
+)
+
+const (
+	errInvalidMerge = "failed to merge values"
 )
 
 type errNotFound struct {
@@ -392,3 +401,43 @@ func (p *Paved) SetBool(path string, value bool) error {
 func (p *Paved) SetNumber(path string, value float64) error {
 	return p.SetValue(path, value)
 }
+
+// merges the given src onto the given dst.
+// dst and src must have the same map type.
+// If a nil merge options is supplied, the default behavior is MergeOptions'
+// default behavior. If dst or src is nil, src is returned
+// (i.e., dst replaced by src).
+func merge(dst, src interface{}, mergeOptions *xpv1.MergeOptions) (interface{}, error) {
+	if dst == nil || src == nil {
+		return src, nil // no merge, replace
+	}
+
+	m, ok := dst.(map[string]interface{})
+	if reflect.TypeOf(src).Kind() != reflect.Map || !ok {
+		return src, nil // not a map nor a struct, mergo cannot merge
+	}
+
+	// use merge semantics with the configured merge options to obtain the target dst value
+	if err := mergo.Merge(&m, src, mergeOptions.MergoConfiguration()...); err != nil {
+		return nil, errors.Wrap(err, errInvalidMerge)
+	}
+	return m, nil
+}
+
+// MergeValue of the receiver p at the specified field path with the supplied
+// value according to supplied merge options
+func (p *Paved) MergeValue(path string, value interface{}, mo *xpv1.MergeOptions) error {
+	dst, err := p.GetValue(path)
+	if IsNotFound(err) || mo == nil {
+		dst = nil
+	} else if err != nil {
+		return err
+	}
+
+	dst, err = merge(dst, value, mo)
+	if err != nil {
+		return err
+	}
+
+	return p.SetValue(path, dst)
+}

pkg/resource/api.go

@@ -28,7 +28,8 @@ import (
 	"k8s.io/apimachinery/pkg/types"
 	"sigs.k8s.io/controller-runtime/pkg/client"
 
-	"github.com/crossplane/crossplane-runtime/pkg/fieldpath"
+	xpv1 "github.com/crossplane/crossplane-runtime/apis/common/v1"
+	fobj "github.com/crossplane/crossplane-runtime/pkg/fieldpath/object"
 	"github.com/crossplane/crossplane-runtime/pkg/meta"
 )
 
@@ -156,9 +157,9 @@ func (a *APIPatchingApplicator) Apply(ctx context.Context, o client.Object, ao .
 // WithMergeOptions returns an ApplyOption for merging the value at the given
 // fieldPath of desired object onto the current object with
 // the given merge options.
-func WithMergeOptions(fieldPath string, mergeOptions *fieldpath.MergeOptions) ApplyOption {
+func WithMergeOptions(fieldPath string, mergeOptions *xpv1.MergeOptions) ApplyOption {
 	return func(_ context.Context, current, desired runtime.Object) error {
-		return fieldpath.MergeReplace(fieldPath, current, desired, mergeOptions)
+		return fobj.MergeReplace(fieldPath, current, desired, mergeOptions)
 	}
 }