[milo] Add BuildSummary and common models.

milo/appengine/common/model/manifest_link.go

Index: milo/appengine/common/model/manifest_link.go
diff --git a/milo/appengine/common/model/manifest_link.go b/milo/appengine/common/model/manifest_link.go
new file mode 100644
index 0000000000000000000000000000000000000000..6123dba088529c3c5467faa04847ec1bd18f0bb3
--- /dev/null
+++ b/milo/appengine/common/model/manifest_link.go
@@ -0,0 +1,45 @@
+// Copyright 2017 The LUCI Authors. All rights reserved.
+// Use of this source code is governed under the Apache License, Version 2.0
+// that can be found in the LICENSE file.
+
+package model
+
+import (
+	"bytes"
+
+	ds "github.com/luci/gae/service/datastore"
+	"github.com/luci/luci-go/common/data/cmpbin"
+)
+
+// ManifestLink is an in-MILO link to a named source manifest.
+type ManifestLink struct {
+	// The name of the manifest as the build annotated it.
+	Name string
+
+	// The manifest ID (sha256).
+	ID []byte
+}
+
+var _ ds.PropertyConverter = (*ManifestLink)(nil)
+
+// FromProperty implements ds.PropertyConverter
+func (m *ManifestLink) FromProperty(p ds.Property) (err error) {
+	val, err := p.Project(ds.PTBytes)
+	if err != nil {
+		return err
+	}
+	buf := bytes.NewReader(val.([]byte))
+	if m.Name, _, err = cmpbin.ReadString(buf); err != nil {
+		return
+	}
+	m.ID, _, err = cmpbin.ReadBytes(buf)
+	return
+}
+
+// ToProperty implements ds.PropertyConverter
+func (m *ManifestLink) ToProperty() (ds.Property, error) {
+	buf := bytes.NewBuffer(nil)
+	cmpbin.WriteString(buf, m.Name)

[Ryan Tseng, 2017/06/17 00:44:29]

These functions return errors, should probably propagate them

[iannucci, 2017/06/17 01:30:04]

They only return errors if the write returns an error. bytes.Buffer writes can't
return errors :)

+	cmpbin.WriteBytes(buf, m.ID)
+	return ds.MkProperty(buf.Bytes()), nil
+}