Stop various JSON field from being sent with null values

client/packages.go

@@ -20,6 +20,7 @@
 package client
 
 import (
+	"encoding/json"
 	"errors"
 	"fmt"
 	"net/url"
@@ -35,37 +36,52 @@ type Snap struct {
 	Title            string        `json:"title,omitempty"`
 	Summary          string        `json:"summary"`
 	Description      string        `json:"description"`
-	DownloadSize     int64         `json:"download-size"`
-	Icon             string        `json:"icon"`
-	InstalledSize    int64         `json:"installed-size"`
-	InstallDate      time.Time     `json:"install-date"`
+	DownloadSize     int64         `json:"download-size,omitempty"`
+	Icon             string        `json:"icon,omitempty"`
+	InstalledSize    int64         `json:"installed-size,omitempty"`
+	InstallDate      time.Time     `json:"install-date,omitempty"`
 	Name             string        `json:"name"`
 	Developer        string        `json:"developer"`
 	Status           string        `json:"status"`
 	Type             string        `json:"type"`
 	Version          string        `json:"version"`
 	Channel          string        `json:"channel"`
-	TrackingChannel  string        `json:"tracking-channel"`
-	IgnoreValidation bool          `json:"ignore-validation"`
+	TrackingChannel  string        `json:"tracking-channel,omitempty"`
+	IgnoreValidation bool          `json:"ignore-validation,omitempty"`
 	Revision         snap.Revision `json:"revision"`
 	Confinement      string        `json:"confinement"`
-	Private          bool          `json:"private"`
-	DevMode          bool          `json:"devmode"`
-	JailMode         bool          `json:"jailmode"`
-	TryMode          bool          `json:"trymode"`
-	Apps             []AppInfo     `json:"apps"`
-	Broken           string        `json:"broken"`
+	Private          bool          `json:"private,omitempty"`
+	DevMode          bool          `json:"devmode,omitempty"`
+	JailMode         bool          `json:"jailmode,omitempty"`
+	TryMode          bool          `json:"trymode,omitempty"`
+	Apps             []AppInfo     `json:"apps,omitempty"`
+	Broken           string        `json:"broken,omitempty"`
 	Contact          string        `json:"contact"`
 	License          string        `json:"license,omitempty"`
 
-	Prices      map[string]float64 `json:"prices"`
-	Screenshots []Screenshot       `json:"screenshots"`
+	Prices      map[string]float64 `json:"prices,omitempty"`
+	Screenshots []Screenshot       `json:"screenshots,omitempty"`
 
 	// The flattended channel map with $track/$risk
-	Channels map[string]*snap.ChannelSnapInfo `json:"channels"`
+	Channels map[string]*snap.ChannelSnapInfo `json:"channels,omitempty"`
 
 	// The ordered list of tracks that contains channels
-	Tracks []string
+	Tracks []string `json:"tracks,omitempty"`
+}
+
+func (s *Snap) MarshalJSON() ([]byte, error) {
+	type auxSnap Snap // use auxiliary type so that Go does not call Snap.MarshalJSON()
+	// separate type just for marshalling
+	m := struct {
+		auxSnap
+		InstallDate *time.Time `json:"install-date,omitempty"`
+	}{
+		auxSnap: auxSnap(*s),
+	}
+	if !s.InstallDate.IsZero() {
+		m.InstallDate = &s.InstallDate
+	}
+	return json.Marshal(&m)
 }
 
 type Screenshot struct {

daemon/api_test.go

@@ -1419,7 +1419,7 @@ func (s *apiSuite) TestFind(c *check.C) {
 	c.Assert(snaps, check.HasLen, 1)
 	c.Assert(snaps[0]["name"], check.Equals, "store")
 	c.Check(snaps[0]["prices"], check.IsNil)
-	c.Check(snaps[0]["screenshots"], check.HasLen, 0)
+	c.Check(snaps[0]["screenshots"], check.IsNil)
 	c.Check(snaps[0]["channels"], check.IsNil)
 
 	c.Check(rsp.SuggestedCurrency, check.Equals, "EUR")

daemon/response_test.go

@@ -20,6 +20,7 @@
 package daemon
 
 import (
+	"encoding/json"
 	"fmt"
 	"io/ioutil"
 	"net/http"
@@ -97,3 +98,12 @@ func (s *responseSuite) TestFileResponseSetsContentDisposition(c *check.C) {
 	c.Check(hdr.Get("Content-Disposition"), check.Equals,
 		fmt.Sprintf("attachment; filename=%s", filename))
 }
+
+// Due to how the protocol was defined the result must be sent, even if it is
+// null. Older clients rely on this.
+func (s *responseSuite) TestRespJSONWithNullResult(c *check.C) {
+	rj := &respJSON{Result: nil}
+	data, err := json.Marshal(rj)
+	c.Assert(err, check.IsNil)
+	c.Check(string(data), check.Equals, `{"type":"","status-code":0,"status":"","result":null}`)
+}