fix(genapi): uint64 fields failing to be unmarshalled (#2492)

uint64 fields get marshalled into json by protobuf as strings, so we
have to tell the json parser to look for strings when unmarshalling.

internal/api/genapi/input.go

@@ -58,6 +58,7 @@ type fieldInfo struct {
 	SubtypeNames      []string
 	Query             bool
 	SkipDefault       bool
+	JsonTags          []string // Appended to a field's `json` tag (comma separated)
 }
 
 type structInfo struct {
@@ -832,6 +833,13 @@ var inputStructs = []*structInfo{
 	{
 		inProto: &sessions.Connection{},
 		outFile: "sessions/connection.gen.go",
+		fieldOverrides: []fieldInfo{
+			// uint64 fields get marshalled by protobuf as strings, so we have
+			// to tell the json parser that their json representation is a
+			// string but they go into Go uint64 types.
+			{Name: "BytesUp", JsonTags: []string{"string"}},
+			{Name: "BytesDown", JsonTags: []string{"string"}},
+		},
 	},
 	{
 		inProto: &sessions.Session{},

internal/api/genapi/templates.go

@@ -85,6 +85,9 @@ func fillTemplates() {
 					if override.FieldType != "" {
 						field.FieldType = override.FieldType
 					}
+					if len(override.JsonTags) != 0 {
+						field.JsonTags = override.JsonTags
+					}
 					in.generatedStructure.fields[i] = field
 				}
 			}
@@ -578,6 +581,7 @@ func hasResponseType(types []string, typ string) bool {
 var structTemplate = template.Must(template.New("").Funcs(
 	template.FuncMap{
 		"hasResponseType": hasResponseType,
+		"stringsjoin":     strings.Join,
 	},
 ).Parse(
 	fmt.Sprint(`// Code generated by "make api"; DO NOT EDIT.
@@ -595,7 +599,7 @@ import (
 )
 
 type {{ .Name }} struct { {{ range .Fields }}
-{{ .Name }}  {{ .FieldType }} `, "`json:\"{{ .ProtoName }},omitempty\"`", `{{ end }}
+{{ .Name }}  {{ .FieldType }} `, "`json:\"{{ .ProtoName }}{{ if ( ne ( len ( .JsonTags ) ) 0 ) }},{{ stringsjoin .JsonTags \",\" }}{{ end }},omitempty\"`", `{{ end }}
 {{ if ( not ( eq ( len ( .CreateResponseTypes ) ) 0 ) )}}
 	response *api.Response
 {{ else if ( eq .Name "Error" ) }}