Uncaught Error: compare on non-nil objects of different types

[scttnlsn]

I'm getting this error occasionally when calling transact!. The only pattern I could find possibly has something to do with the underscores in the following example...

This always throws an error:

(d/transact! conn [{:db/id -1 :test/foo "foo" :test/_bar {:baz "qux"}}])

But these always work fine:

(d/transact! conn [{:db/id -1 :test/foo "foo" :test/bar {:baz "qux"}}])
(d/transact! conn [{:db/id -1 :test/_bar {:baz "qux"}}])
(d/transact! conn [{:db/id -1 :test/foo "foo" :test/_bar 123}])

Here's the JavaScript stack trace:

compare (core.cljs:1521)
cmp (core.cljs:44)
cmp_datoms_eavt (core.cljs:48)
binary_search_l (btset.cljs:33)
_seek (btset.cljs:382)
_slice (btset.cljs:404)
datascript.btset.slice.slice__3 (btset.cljs:414)
datascript.btset.slice.slice (btset.cljs:412)
datascript.btset.slice.slice__2 (btset.cljs:411)
datascript.btset.slice.slice (btset.cljs:412)
datascript.core.DB.datascript$core$ISearch$_search$arity$2 (core.cljs:80)
_search (core.cljs:31)
transact_add (core.cljs:192)
transact_tx_data (core.cljs:249)
with$ (datascript.cljs:37)
(anonymous function) (datascript.cljs:45)
cljs.core.swap_BANG_.swap_BANG___2 (core.cljs:3348)
cljs.core.swap_BANG_.swap_BANG_ (core.cljs:3358)
_transact_BANG_ (datascript.cljs:44)
transact_BANG_ (datascript.cljs:51)

Any ideas?

[tonsky]

Underscores sure are a problem. When you write [:db/add X :test/_bar Y] it reads backwards, meaning “put a reference from Y to X via :test/bar property”. So it expects both X and Y to be integers. In your case, you put hashmap at Y pos, and that wouldn’t work as an entity id.

So two problems for me to fix here:

1. Error message should be improved (sorry about that)

2. Error should be thrown in second case (you don’t get it here by pure luck):

   (d/transact! conn [{:db/id -1 :test/_bar {:baz "qux"}}])

[scttnlsn]

@tonsky Okay, thanks. I'll have to read the Datomic docs about this. I don't get any error when there's only a single attribute (like no. 2 above).

[tonsky]

datomic allows to specify maps when creating nested relation, but ds does not support this feature yet. what about backward relation, I'm no sure that even datomic supports that=