ebuchman: added some demos on how to parse unknown types

rpc/lib/server/parse_test.go

@@ -0,0 +1,133 @@
+package rpcserver
+
+import (
+	"encoding/json"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/tendermint/go-wire/data"
+)
+
+func TestParseJSONMap(t *testing.T) {
+	assert := assert.New(t)
+
+	input := []byte(`{"value":"1234","height":22}`)
+
+	// naive is float,string
+	var p1 map[string]interface{}
+	err := json.Unmarshal(input, &p1)
+	if assert.Nil(err) {
+		h, ok := p1["height"].(float64)
+		if assert.True(ok, "%#v", p1["height"]) {
+			assert.EqualValues(22, h)
+		}
+		v, ok := p1["value"].(string)
+		if assert.True(ok, "%#v", p1["value"]) {
+			assert.EqualValues("1234", v)
+		}
+	}
+
+	// preloading map with values doesn't help
+	tmp := 0
+	p2 := map[string]interface{}{
+		"value":  &data.Bytes{},
+		"height": &tmp,
+	}
+	err = json.Unmarshal(input, &p2)
+	if assert.Nil(err) {
+		h, ok := p2["height"].(float64)
+		if assert.True(ok, "%#v", p2["height"]) {
+			assert.EqualValues(22, h)
+		}
+		v, ok := p2["value"].(string)
+		if assert.True(ok, "%#v", p2["value"]) {
+			assert.EqualValues("1234", v)
+		}
+	}
+
+	// preload here with *pointers* to the desired types
+	// struct has unknown types, but hard-coded keys
+	tmp = 0
+	p3 := struct {
+		Value  interface{} `json:"value"`
+		Height interface{} `json:"height"`
+	}{
+		Height: &tmp,
+		Value:  &data.Bytes{},
+	}
+	err = json.Unmarshal(input, &p3)
+	if assert.Nil(err) {
+		h, ok := p3.Height.(*int)
+		if assert.True(ok, "%#v", p3.Height) {
+			assert.Equal(22, *h)
+		}
+		v, ok := p3.Value.(*data.Bytes)
+		if assert.True(ok, "%#v", p3.Value) {
+			assert.EqualValues([]byte{0x12, 0x34}, *v)
+		}
+	}
+
+	// simplest solution, but hard-coded
+	p4 := struct {
+		Value  data.Bytes `json:"value"`
+		Height int        `json:"height"`
+	}{}
+	err = json.Unmarshal(input, &p4)
+	if assert.Nil(err) {
+		assert.EqualValues(22, p4.Height)
+		assert.EqualValues([]byte{0x12, 0x34}, p4.Value)
+	}
+
+	// so, let's use this trick...
+	// dynamic keys on map, and we can deserialize to the desired types
+	var p5 map[string]*json.RawMessage
+	err = json.Unmarshal(input, &p5)
+	if assert.Nil(err) {
+		var h int
+		err = json.Unmarshal(*p5["height"], &h)
+		if assert.Nil(err) {
+			assert.Equal(22, h)
+		}
+
+		var v data.Bytes
+		err = json.Unmarshal(*p5["value"], &v)
+		if assert.Nil(err) {
+			assert.Equal(data.Bytes{0x12, 0x34}, v)
+		}
+	}
+}
+
+func TestParseJSONArray(t *testing.T) {
+	assert := assert.New(t)
+
+	input := []byte(`["1234",22]`)
+
+	// naive is float,string
+	var p1 []interface{}
+	err := json.Unmarshal(input, &p1)
+	if assert.Nil(err) {
+		v, ok := p1[0].(string)
+		if assert.True(ok, "%#v", p1[0]) {
+			assert.EqualValues("1234", v)
+		}
+		h, ok := p1[1].(float64)
+		if assert.True(ok, "%#v", p1[1]) {
+			assert.EqualValues(22, h)
+		}
+	}
+
+	// preloading map with values helps here (unlike map - p2 above)
+	tmp := 0
+	p2 := []interface{}{&data.Bytes{}, &tmp}
+	err = json.Unmarshal(input, &p2)
+	if assert.Nil(err) {
+		v, ok := p2[0].(*data.Bytes)
+		if assert.True(ok, "%#v", p2[0]) {
+			assert.EqualValues([]byte{0x12, 0x34}, *v)
+		}
+		h, ok := p2[1].(*int)
+		if assert.True(ok, "%#v", p2[1]) {
+			assert.EqualValues(22, *h)
+		}
+	}
+}