如何使用Go语言在Google App Engine中通过键获取实体

now I add some entity in datastore using Go language, I can query all entity, but I want get a entity by key, how to get entity'key and query by key like this: select * from Blog where key=?

c := appengine.NewContext(r)
g := Blog{
Title: r.FormValue("title"),
    Content: r.FormValue("content"),
}
_, err := datastore.Put(c, datastore.NewIncompleteKey(c, "Blog", nil), &g)

Thanks

See the Datastore documentation for the Go Runtime:

var b Blog
err := datastore.Get(c, key, &b)