Custom datastore properties

[matthew...@workiva.com]

I am trying to understand the recommended way to make custom datastore properties via the PropertyLoadSaver interface.  From what I can tell from reading the source for newStructPLS, you have to provide Load() and Save() on the upper level model struct, not on the property itself.  I've made a little go package that provides a JsonProperty map[string]interface{} which is saved into the datastore as a string and it works ok, but the usage is a little more verbose than I would like especially compared to Python.

https://github.com/matthewbelisle-wf/jsonproperty

My question for the go/datastore experts is - does that seem like a good way in general to make a custom property?  Or is there an easier/cleaner way to do it?

[Matthew Zimmerman]

Generally I think the interface was provided to give a way to
save/load data that doesn't conform to the standard types given. It
also helps on types that compute data on load, like in their example.

func (x *CustomPropsExample) Load(c <-chan Property) error {
// Load I and J as usual.
if err := datastore.LoadStruct(x, c); err != nil {
return err
}
// Derive the Sum field.
x.Sum = x.I + x.J
return nil
}

I don't understand the use case from what you've provided and why you
wouldn't just make the json an embedded struct.

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[matthew...@workiva.com]

The use case is that this one can store arbitrary data, whereas embedded structs have to have their fields/types known before hand.

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