// Wrap wraps a given datastore with a key-prefix.
func Wrap(child ds.Datastore, prefix ds.Key) ktds.Datastore {
	if child == nil {
		panic("child (ds.Datastore) is nil")
	}

	d := ktds.Wrap(child, PrefixTransform(prefix))
	return &datastore{Datastore: d, raw: child, prefix: prefix}
}
Example #2
0
func (d *Datastore) Query(q query.Query) (query.Results, error) {
	if len(q.Filters) > 0 ||
		len(q.Orders) > 0 ||
		q.Limit > 0 ||
		q.Offset > 0 {
		// TODO this is overly simplistic, but the only caller is
		// `ipfs refs local` for now, and this gets us moving.
		return nil, errors.New("mount only supports listing all prefixed keys in random order")
	}
	key := datastore.NewKey(q.Prefix)
	ds, mount, k := d.lookup(key)
	if ds == nil {
		return nil, errors.New("mount only supports listing a mount point")
	}
	// TODO support listing cross mount points too

	// delegate the query to the mounted datastore, while adjusting
	// keys in and out
	q2 := q
	q2.Prefix = k.String()
	wrapDS := keytransform.Wrap(ds, &keytransform.Pair{
		Convert: func(datastore.Key) datastore.Key {
			panic("this should never be called")
		},
		Invert: func(k datastore.Key) datastore.Key {
			return mount.Child(k)
		},
	})

	r, err := wrapDS.Query(q2)
	if err != nil {
		return nil, err
	}
	r = query.ResultsReplaceQuery(r, q)
	return r, nil
}
func (ks *DSSuite) TestBasic(c *C) {

	pair := &kt.Pair{
		Convert: func(k ds.Key) ds.Key {
			return ds.NewKey("/abc").Child(k)
		},
		Invert: func(k ds.Key) ds.Key {
			// remove abc prefix
			l := k.List()
			if l[0] != "abc" {
				panic("key does not have prefix. convert failed?")
			}
			return ds.KeyWithNamespaces(l[1:])
		},
	}

	mpds := ds.NewMapDatastore()
	ktds := kt.Wrap(mpds, pair)

	keys := strsToKeys([]string{
		"foo",
		"foo/bar",
		"foo/bar/baz",
		"foo/barb",
		"foo/bar/bazb",
		"foo/bar/baz/barb",
	})

	for _, k := range keys {
		err := ktds.Put(k, []byte(k.String()))
		c.Check(err, Equals, nil)
	}

	for _, k := range keys {
		v1, err := ktds.Get(k)
		c.Check(err, Equals, nil)
		c.Check(bytes.Equal(v1.([]byte), []byte(k.String())), Equals, true)

		v2, err := mpds.Get(ds.NewKey("abc").Child(k))
		c.Check(err, Equals, nil)
		c.Check(bytes.Equal(v2.([]byte), []byte(k.String())), Equals, true)
	}

	run := func(d ds.Datastore, q dsq.Query) []ds.Key {
		r, err := d.Query(q)
		c.Check(err, Equals, nil)

		e, err := r.Rest()
		c.Check(err, Equals, nil)

		return ds.EntryKeys(e)
	}

	listA := run(mpds, dsq.Query{})
	listB := run(ktds, dsq.Query{})
	c.Check(len(listA), Equals, len(listB))

	// sort them cause yeah.
	sort.Sort(ds.KeySlice(listA))
	sort.Sort(ds.KeySlice(listB))

	for i, kA := range listA {
		kB := listB[i]
		c.Check(pair.Invert(kA), Equals, kB)
		c.Check(kA, Equals, pair.Convert(kB))
	}

	c.Log("listA: ", listA)
	c.Log("listB: ", listB)
}