How to catch constraint errors?

I need to catch only database constraint errors emitted by table.unique(["foo", "bar"]); entry in the schema.

I can do that now with a really hacky Promise#catch(…) predicate:

function isUniqueConstraintError(err){
    if (!err) return false;
    var re = /^duplicate key value violates unique constraint/;  
    return re.test(err.message);                                 
}

MyModel.forge({ foo: "fuz", bar: "fiz" })
.save()
.catch(isUniqueConstraintError, function(err) {
    // Handle the error
});

but this is obviously very brittle.

Is there a more robust way to catch this?

[vishchiv]

Error object has code property, so I would better try to match errors by error code. e.g. for postgres https://www.postgresql.org/docs/9.6/errcodes-appendix.html

[hasahmed]

Did anything ever come of this? It would be really nice to have errors be consistent across database engines.