wishlist: Support an encoding/* style "decode into a struct / encode a struct" api

[tv42]

I wish I had an OGDL library that looked like everything else under encoding/*.

Yes, it'll lose information, and can't round-trip all OGDL data. But it's way more convenient to use than needing to run "queries" on a thing on every access, or writing a function that runs all those queries and returns a struct with the results..

Think of it as ogdl.Graph being the moral equivalent of decoding JSON to interface{}. Used when you know you need to round-trip, but otherwise painful.

It could use struct tags in a way vary similar to encoding/xml, and allow the user to put ogdl paths in them. Something like

network
  eth0
    ip   192.168.0.10
    mask 255.255.255.0
    gw   192.168.0.1

hostname crispin
nameserver 8.8.8.8
nameserver 8.8.4.4

type Config struct {
    Hostname string
    // decoding to a map type knows that the subgraph should be >=2
    // levels deep, first level becomes the keys
    Network map[string]*Interface
    // decoding to a slice value appends every matching subgraph
    Nameserver []net.IP
}

type Interface struct {
    IP      net.IP `ogdl:"ip"`
    Netmask net.IP `ogdl:"mask"`
    Gateway net.IP `ogdl:"gw"`
}

And naturally each field would use encoding/text to actually parse the string. And if the value isn't a string but a subgraph, you could see if the field has a UnmarshalOGDL / MarshalOGDL method, just like JSON; the input to such unmarshal would be a Graph, not []byte.

Even more ideally, this would tie into a streaming parser and avoid holding the graph in memory all at once. And the above UnmarshalOGDL could tie into EventHandler or Parser somehow, too.

[tv42]

And an example of OGDL paths in struct tag would be something like

noise
  goodstuff 42

type T struct {
    Value int `ogdl:"noise.goodstuff"`
}

[rveen]

Your wish is totally justified. Hǎiliàng Wang has started working in that direction.