Rethinkdbdash and client side backtraces posted on 15 August 2015

A bit of context

I released rethinkdbdash 2.1.3 (and 2.1.4) a bit earlier today. This release besides adding a few missing syntaxes for 2.1 (r.union and condition.branch(...)), fixed an issue with the client-side backtraces, though to be honest, the client-side backtraces were not really working before.

If a RethinkDB query throws an error, the server will provide a backtrace and the driver will reconstruct the query and underline the broken part. For example if a table is missing you will see this error:

ReqlOpFailedError: Table `test.users` does not exist in:
r.db("test").table("users").filter(function(var_1) {
    return var_1("age").gt(18)

The query is printed back and the broken parts are highlighted. These backtraces are in my opinion of the little one of the little things that makes RethinkDB enjoyable to use. However a few queries cannot be sent to the server and therefore no backtraces are available. Because RethinkDB stores JSON document, some JavaScript values are forbidden, typically NaN and Infinity. When the driver finds a forbidden value, it used to just throw an error saying NaN cannot be converted to JSON. This is painful for two reasons:

  • The presence of NaN is an operational error and the driver should just reject the query, not throw.
  • NaN can easily propages and you basically have to inspect all possible variables. The bigger your query, the harder debugging it is.

What’s new

Since 2.1.3, Rethinkdbdash now builds backtraces for these errors and will point exactly where the problem is.

var r = require('rethinkdbdash')();

var ADULT_AGE = 18;
var ADULT_AGE_US = NaN; // oops

r.db('test').table('users').merge(function(user) {
  return r.branch(
    { canDrink: user('age').gt(ADULT_AGE_US) },
    { canDrink: user('age').gt(ADULT_AGE) }
}).run().then(console.log).error(function(error) {

What will be printed is:

ReqlRuntimeError: Cannot convert `NaN` to JSON in:
r.db("test").table("users").merge(function(var_1) {
    return r.branch(var_1("location").eq("US"), {
        canDrink: var_1("age").gt(NaN)
    }, {
        canDrink: var_1("age").gt(18)

Pretty cool uh? You can pin exactly where the NaN value is.

Feedback/suggestions? Ping me on Twitter via @neumino or shoot me an email at [email protected].