go-ipld-prime-proto

This Go module is deprecated. Use go-codec-dagpb instead.

An implementation of the DAG Protobuf for the go-ipld-prime library

Background
Install
Usage
Contribute
License

Background

The package adds Dag Protobuf support to go-ipld-prime. It is designed primarily as an adjunct to go-ipld-prime to enable using selectors and Graphsync, features which are unique to go-ipld-prime, with UnixFS v1 files encoded in protobuf.

go-ipld-prime-proto is primarily used to run selectors against Dag Protobuf encoded IPLD Graphs. It does not include robust facilities to support actual creation of DAG protobuf nodes, and none of the actual features for working with files contained in UnixFS. However, it can read, traverse and copy UnixFS data, which is what you need to run selectors and graphsync against existing UnixFS data.

Install

go-ipld-prime-proto requires Go >= 1.13 and can be installed using Go modules

Usage

To run a selector traversal against a graph encoded in Dag-Protobuf, you need to configure it with a custom NodeBuilderChooser. The simplest way to create such a node builder chooser is to take an existing function and pass it to AddDagPBSupportToChooser. This will add support for Dag Protobuf and Raw node encodings, the two types required by UnixFS.

Example:

var existing traversal.NodeBuilderChooser = func(ipld.Link, ipld.LinkContext) ipld.NodeBuilder {
	return ipldfree.NodeBuilder()
}
  
var pbChooser traversal.NodeBuilderChooser = 
dagpb.AddDagPBSupportToChooser(existing)

var selector selector.Selector
var loader ipld.Loader
var unixfsCid cid.Cid

// Load the first node
unixFSRootNode, err := cidlink.Link{Cid: unixfsCid}.Load(ipld.LinkContext{}, dagpb.PBNode__NodeBuilder(), loader)

// execute the traversal
err = traversal.Progress{
  Cfg: &traversal.Config{
    LinkLoader:             loader,
    LinkNodeBuilderChooser: pbChooser,
  },
}.WalkAdv(unixFSRootNode, allSelector, func(pg traversal.Progress, nd ipld.Node, r traversal.VisitReason) error {
  // do something with your traversed nodes here
}