Milo: Print raw json for buildbot build properties

milo/appengine/common/funcs.go

Index: milo/appengine/common/funcs.go
diff --git a/milo/appengine/common/funcs.go b/milo/appengine/common/funcs.go
index 041ce8f9d8256473415616f5a8fc5b55eec41cb1..014af7e336d895d6c035538168e5dcbc5d52a110 100644
--- a/milo/appengine/common/funcs.go
+++ b/milo/appengine/common/funcs.go
@@ -6,6 +6,7 @@ package common
 
 import (
 	"bytes"
+	"encoding/json"
 	"fmt"
 	"html/template"
 	"strings"
@@ -28,6 +29,7 @@ var funcMap = template.FuncMap{
 	"startswith":     strings.HasPrefix,
 	"sub":            sub,
 	"consoleHeader":  consoleHeader,
+	"formatJson":     formatJson,
 }
 
 // localTime returns a <span> element with t in human format
@@ -201,6 +203,30 @@ func shortHash(s string) string {
 	return s
 }
 
+// If the string s is a JSON map, then pretty print it.
+func formatJson(s string) template.HTML {
+	var o interface{}
+	err := json.Unmarshal([]byte(s), &o)

[nodir, 2017/03/24 06:05:40]

here we parse a JSON-formatted value and then conditionally format to JSON
back.. Earlier in the code path with had this value in parsed form, so we did
(parsed -> JSON -> parsed -> JSON) conversion. This is wasteful

Please change formatJson to accept an interface{} and treat the passed value as
already parsed.

Also please rename formatJson to formatJSON because Go likes abbreviation
written with all caps

+	if err != nil {
+		return template.HTML(template.HTMLEscapeString(s))
+	}
+	switch t := o.(type) {
+	case string:
+		return template.HTML(template.HTMLEscapeString(t))
+	case map[string]interface{}:
+		s, err := json.MarshalIndent(t, "", "  ")

[nodir, 2017/03/24 06:05:40]

AFAIR last time we talked about this I asked to render property values of any
type in JSON format, so that a user can clearly see the value type. It is
imporatnt to know the type because users write code that works with the values.
Today it is ambiguous, value `1` may be a string "1" or a number 1. Print only
structs as JSON but other types is confusing. A person who sees a JSON object
presented as valid JSON may reasonably assume that in general milo presents
values in JSON format.

Please format all values in JSON format.

[nodir, 2017/03/24 08:46:06]

Obviously please update the code that is currently encodes values in
JSON before passing them to build page template. Make it pass raw typed values. 

+		if err == nil {
+			es := strings.Split(string(s), "\n")
+			var result string
+			for _, line := range es {
+				result += strings.Replace(template.HTMLEscapeString(line), " ", "&nbsp;", -1) + "<br>"
+			}
+			return template.HTML("<div class=\"left\">" + result + "</span>")
+		}
+	}
+	return template.HTML(template.HTMLEscapeString(s))
+}
+
 func init() {
 	linkifySetTemplate = template.Must(
 		template.New("linkifySet").