ipld.md

Given this Data

{
  "a": "b",
  "c": [
    {},
    {
      "d": 111,
      "e": {"/": "/ipld/QmAAA..."}
    },
  ]
}
// QmBBB...


{
  "f": "g",
  "h": [0, 10, 20, 30]
}
// QmAAA...

Can use these structs to read it:

type Foo struct {
  a string
  c []FooChild
}

type FooChild struct {
  d int
  e ipld.Link
}

type Bar struct {
  f string
  h []int
}

// one interface
dag := mkDag(kvStore)
var val int
ipld.Resolve(dag, "QmBBB.../c/1/e/h/2", &val)
assert(val == 20)

// another interface
dag := mkDag(kvStore)
var val Bar
ipld.Resolve(dag, "QmBBB.../c/1/e/", &val)
assert(val.h[2] == 20)

// another interface
dag := mkDag(kvStore)
data := dag.Get("QmBBB...") // raw bytes (could be json, or cbor, or whatever)
var val int
ipld.Resolve(dag, data, "c/1/e/h/2", &val)
assert(val == 20)

Where dag is a thing that implements or uses something like this:

type Data interface { // or DAG or DagPatch or IPLDCodec or ...
  // Resolve populates value val with the value at path.
  // if path traverses beyond the confines of the available data,
  // the last value reached is used, and a pathRest is the path remaining
  // to be resolved.
  Resolve(path string, val interface{}) (pathRest string, err error)

  // Tree lists all paths starting from path, rooted at this object.
  // Effectively:
  //  > find $objhash/<path>
  Tree(path string) (paths []string, err error)
}

jbenet/ipld.md

Given this Data