Question

It seems mongo does not allow insertion of keys with a dot (.) or dollar sign ($) however when I imported a JSON file that contained a dot in it using the mongoimport tool it worked fine. The driver is complaining about trying to insert that element.

This is what the document looks like in the database:

{
    "_id": {
        "$oid": "..."
    },
    "make": "saab",
    "models": {
        "9.7x": [
            2007,
            2008,
            2009,
            2010
        ]
    }
}

Am I doing this all wrong and should not be using hash maps like that with external data (i.e. the models) or can I escape the dot somehow? Maybe I am thinking too much Javascript-like.

Answer 1

MongoDB doesn’t support keys with a dot in them so you’re going to have to preprocess your JSON file to remove/replace them before importing it or you’ll be setting yourself up for all sorts of problems.

There isn’t a standard workaround to this issue, the best approach is too dependent upon the specifics of the situation. But I’d avoid any key encoder/decoder approach if possible as you’ll continue to pay the inconvenience of that in perpetuity, where a JSON restructure would presumably be a one-time cost.