Utilities for working with map[string]interface{} + yaml.Node

kyaml/filtersutil/doc.go

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+// Copyright 2019 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+// Package filtersutil provides utilities for working with yaml.Filter and
+// kio.Filter interfaces.
+package filtersutil

kyaml/filtersutil/example_test.go

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+// Copyright 2019 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+package filtersutil_test
+
+import (
+	"bytes"
+	"fmt"
+	"log"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"sigs.k8s.io/kustomize/kyaml/filtersutil"
+	"sigs.k8s.io/kustomize/kyaml/kio"
+	"sigs.k8s.io/kustomize/kyaml/yaml"
+)
+
+func TestApplyToJSON(t *testing.T) {
+	// testFilter sets `foo: bar` on each resource
+	testFilter := kio.FilterAll(yaml.FilterFunc(
+		func(node *yaml.RNode) (*yaml.RNode, error) {
+			set := yaml.SetField(
+				"foo", yaml.NewScalarRNode("bar"))
+			err := node.PipeE(set)
+			if !assert.NoError(t, err) {
+				t.FailNow()
+			}
+			return node, nil
+		}))
+
+	obj1 := buffer{Buffer: bytes.NewBufferString(`{"kind": "Foo"}`)}
+	obj2 := buffer{Buffer: bytes.NewBufferString(`{"kind": "Bar"}`)}
+	err := filtersutil.ApplyToJSON(testFilter, obj1, obj2)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	fmt.Println(obj1.String())
+	fmt.Println(obj2.String())
+
+	// Output:
+	// {"foo":"bar","kind":"Foo"}
+	// {"foo":"bar","kind":"Bar"}
+}
+
+type buffer struct {
+	*bytes.Buffer
+}
+
+func (buff buffer) UnmarshalJSON(b []byte) error {
+	buff.Reset()
+	buff.Write(b)
+	return nil
+}
+
+func (buff buffer) MarshalJSON() ([]byte, error) {
+	return buff.Bytes(), nil
+}

kyaml/filtersutil/filtersutil.go

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+// Copyright 2019 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+package filtersutil
+
+import (
+	"encoding/json"
+
+	"sigs.k8s.io/kustomize/kyaml/errors"
+	"sigs.k8s.io/kustomize/kyaml/kio"
+	"sigs.k8s.io/kustomize/kyaml/yaml"
+)
+
+// ApplyToJSON applies the filter to the json objects.
+//
+// ApplyToJSON marshals the objects into a slice of yaml.RNodes, runs
+// the filter on the slice, and then unmarshals the values back.
+//
+// The filter must not create or delete objects because the objects
+// are updated in place.
+func ApplyToJSON(filter kio.Filter, objs ...marshalerUnmarshaler) error {
+	var nodes []*yaml.RNode
+
+	// convert the json objects to rnodes
+	for i := range objs {
+		node, err := getRNode(objs[i])
+		if err != nil {
+			return err
+		}
+		nodes = append(nodes, node)
+	}
+
+	// apply the filter
+	nodes, err := filter.Filter(nodes)
+	if err != nil {
+		return err
+	}
+	if len(nodes) != len(objs) {
+		return errors.Errorf("filter cannot create or delete objects")
+	}
+
+	// convert the rnodes to json objects
+	for i := range nodes {
+		err = setRNode(objs[i], nodes[0])
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+type marshalerUnmarshaler interface {
+	json.Unmarshaler
+	json.Marshaler
+}
+
+// getRNode converts k into an RNode
+func getRNode(k json.Marshaler) (*yaml.RNode, error) {
+	j, err := k.MarshalJSON()
+	if err != nil {
+		return nil, err
+	}
+	return yaml.Parse(string(j))
+}
+
+// setRNode marshals node into k
+func setRNode(k json.Unmarshaler, node *yaml.RNode) error {
+	s, err := node.String()
+	if err != nil {
+		return err
+	}
+	m := map[string]interface{}{}
+	if err := yaml.Unmarshal([]byte(s), &m); err != nil {
+		return err
+	}
+
+	b, err := json.Marshal(m)
+	if err != nil {
+		return err
+	}
+	return k.UnmarshalJSON(b)
+}