Utility to convert versioned runtime objects to a set query parameters

JSON struct tags are used as parameter names, fields that do not have
the omitempty marker are always included.

pkg/conversion/queryparams/convert.go

@@ -0,0 +1,118 @@
+/*
+Copyright 2014 The Kubernetes Authors All rights reserved.
+
+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 queryparams
+
+import (
+	"fmt"
+	"net/url"
+	"reflect"
+	"strings"
+
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/runtime"
+)
+
+func jsonTag(field reflect.StructField) (string, bool) {
+	structTag := field.Tag.Get("json")
+	if len(structTag) == 0 {
+		return "", false
+	}
+	parts := strings.Split(structTag, ",")
+	tag := parts[0]
+	if tag == "-" {
+		tag = ""
+	}
+	omitempty := false
+	parts = parts[1:]
+	for _, part := range parts {
+		if part == "omitempty" {
+			omitempty = true
+			break
+		}
+	}
+	return tag, omitempty
+}
+
+func formatValue(value interface{}) string {
+	return fmt.Sprintf("%v", value)
+}
+
+func isValueKind(kind reflect.Kind) bool {
+	switch kind {
+	case reflect.String, reflect.Bool, reflect.Int, reflect.Int8, reflect.Int16,
+		reflect.Int32, reflect.Int64, reflect.Uint, reflect.Uint8,
+		reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Float32,
+		reflect.Float64, reflect.Complex64, reflect.Complex128:
+		return true
+	default:
+		return false
+	}
+}
+
+func zeroValue(value reflect.Value) bool {
+	return reflect.DeepEqual(reflect.Zero(value.Type()).Interface(), value.Interface())
+}
+
+func addParam(values url.Values, tag string, omitempty bool, value reflect.Value) {
+	if omitempty && zeroValue(value) {
+		return
+	}
+	values.Add(tag, fmt.Sprintf("%v", value.Interface()))
+}
+
+func addListOfParams(values url.Values, tag string, omitempty bool, list reflect.Value) {
+	for i := 0; i < list.Len(); i++ {
+		addParam(values, tag, omitempty, list.Index(i))
+	}
+}
+
+// Convert takes a versioned runtime.Object and serializes it to a url.Values object
+// using JSON tags as parameter names. Only top-level simple values, arrays, and slices
+// are serialized. Embedded structs, maps, etc. will not be serialized.
+func Convert(obj runtime.Object) (url.Values, error) {
+	result := url.Values{}
+	if obj == nil {
+		return result, nil
+	}
+	var sv reflect.Value
+	switch reflect.TypeOf(obj).Kind() {
+	case reflect.Ptr, reflect.Interface:
+		sv = reflect.ValueOf(obj).Elem()
+	default:
+		return nil, fmt.Errorf("Expecting a pointer or interface")
+	}
+	st := sv.Type()
+	if st.Kind() != reflect.Struct {
+		return nil, fmt.Errorf("Expecting a pointer to a struct")
+	}
+	for i := 0; i < st.NumField(); i++ {
+		field := sv.Field(i)
+		tag, omitempty := jsonTag(st.Field(i))
+		if len(tag) == 0 {
+			continue
+		}
+		ft := field.Type()
+		switch {
+		case isValueKind(ft.Kind()):
+			addParam(result, tag, omitempty, field)
+		case ft.Kind() == reflect.Array || ft.Kind() == reflect.Slice:
+			if isValueKind(ft.Elem().Kind()) {
+				addListOfParams(result, tag, omitempty, field)
+			}
+		}
+	}
+	return result, nil
+}

pkg/conversion/queryparams/convert_test.go

@@ -0,0 +1,143 @@
+/*
+Copyright 2014 The Kubernetes Authors All rights reserved.
+
+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 queryparams
+
+import (
+	"net/url"
+	"reflect"
+	"testing"
+
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/runtime"
+)
+
+type namedString string
+type namedBool bool
+
+type bar struct {
+	Float1   float32 `json:"float1"`
+	Float2   float64 `json:"float2"`
+	Int1     int64   `json:"int1,omitempty"`
+	Int2     int32   `json:"int2,omitempty"`
+	Int3     int16   `json:"int3,omitempty"`
+	Str1     string  `json:"str1,omitempty"`
+	Ignored  int
+	Ignored2 string
+}
+
+func (*bar) IsAnAPIObject() {}
+
+type foo struct {
+	Str       string            `json:"str"`
+	Integer   int               `json:"integer,omitempty"`
+	Slice     []string          `json:"slice,omitempty"`
+	Boolean   bool              `json:"boolean,omitempty"`
+	NamedStr  namedString       `json:"namedStr,omitempty"`
+	NamedBool namedBool         `json:"namedBool,omitempty"`
+	Foobar    bar               `json:"foobar,omitempty"`
+	Testmap   map[string]string `json:"testmap,omitempty"`
+}
+
+func (*foo) IsAnAPIObject() {}
+
+func validateResult(t *testing.T, input interface{}, actual, expected url.Values) {
+	local := url.Values{}
+	for k, v := range expected {
+		local[k] = v
+	}
+	for k, v := range actual {
+		if ev, ok := local[k]; !ok || !reflect.DeepEqual(ev, v) {
+			if !ok {
+				t.Errorf("%#v: actual value key %s not found in expected map", input, k)
+			} else {
+				t.Errorf("%#v: values don't match: actual: %#v, expected: %#v", input, v, ev)
+			}
+			break
+		}
+		delete(local, k)
+	}
+	if len(local) > 0 {
+		t.Errorf("%#v: expected map has keys that were not found in actual map: %#v", input, local)
+	}
+}
+
+func TestConvert(t *testing.T) {
+	tests := []struct {
+		input    runtime.Object
+		expected url.Values
+	}{
+		{
+			input: &foo{
+				Str: "hello",
+			},
+			expected: url.Values{"str": {"hello"}},
+		},
+		{
+			input: &foo{
+				Str:     "test string",
+				Slice:   []string{"one", "two", "three"},
+				Integer: 234,
+				Boolean: true,
+			},
+			expected: url.Values{"str": {"test string"}, "slice": {"one", "two", "three"}, "integer": {"234"}, "boolean": {"true"}},
+		},
+		{
+			input: &foo{
+				Str:       "named types",
+				NamedStr:  "value1",
+				NamedBool: true,
+			},
+			expected: url.Values{"str": {"named types"}, "namedStr": {"value1"}, "namedBool": {"true"}},
+		},
+		{
+			input: &foo{
+				Str: "ignore embedded struct",
+				Foobar: bar{
+					Float1: 5.0,
+				},
+			},
+			expected: url.Values{"str": {"ignore embedded struct"}},
+		},
+		{
+			// Ignore untagged fields
+			input: &bar{
+				Float1:   23.5,
+				Float2:   100.7,
+				Int1:     1,
+				Int2:     2,
+				Int3:     3,
+				Ignored:  1,
+				Ignored2: "ignored",
+			},
+			expected: url.Values{"float1": {"23.5"}, "float2": {"100.7"}, "int1": {"1"}, "int2": {"2"}, "int3": {"3"}},
+		},
+		{
+			// include fields that are not tagged omitempty
+			input: &foo{
+				NamedStr: "named str",
+			},
+			expected: url.Values{"str": {""}, "namedStr": {"named str"}},
+		},
+	}
+
+	for _, test := range tests {
+		result, err := Convert(test.input)
+		if err != nil {
+			t.Errorf("Unexpected error while converting %#v: %v", test.input, err)
+		}
+		validateResult(t, test.input, result, test.expected)
+	}
+}

pkg/conversion/queryparams/doc.go

@@ -0,0 +1,19 @@
+/*
+Copyright 2014 The Kubernetes Authors All rights reserved.
+
+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 queryparams provides conversion from versioned
+// runtime objects to URL query values
+package queryparams