我的资料储存库PropertyLoadSaver无法在golang中运作

Question

The documentation I used (https://developers.google.com/appengine/docs/go/datastore/reference#hdr-The_PropertyLoadSaver_Interface)

Just using this struct without using the propertyLoadSaver everything works.

type Trick struct {
    Name string `json:"name" datastore:"-"`
    Difficulty int `json:"difficulty"`
}

When only using a load property it also works.

func (s *Trick) Load(c <-chan datastore.Property) error {
    return datastore.LoadStruct(s, c)
}

The save property results into a appengine panic at the return line?

func (s *Trick) Save(c chan<- datastore.Property) error {
    defer close(c)
    return datastore.SaveStruct(s, c)
}

When I try this instead it will not result into a panic but does not save anything?

func (s *Trick) Save(c chan<- datastore.Property) error {
    defer close(c)
    c <- datastore.Property{
        Name:  "Difficulty",
        Value: s.Difficulty,
    }
    return nil
}

(Using sdk v1.9.8)

Answer 1

Here defer close(c) will cause a panic

func (s *Trick) Save(c chan<- datastore.Property) error {
    defer close(c)
    return datastore.SaveStruct(s, c)
}

The following is ok

func (s *Trick) Save(c chan<- datastore.Property) error {
    return datastore.SaveStruct(s, c)
}

This is also ok

func (s *Trick) Save(c chan<- datastore.Property) error {
    defer close(c)
    c <- datastore.Property{
        Name:  "Difficulty",
        Value: int64(s.Difficulty),
    }
    return nil
}

(please edit the documentation to make this more clear https://developers.google.com/appengine/docs/go/datastore/reference#hdr-The_PropertyLoadSaver_Interface)