CODEWITHSUNDEEP
node.jsmongodbmongoose
iDev247
iDev247

Reputation: 1901

Mongodb (or mongoose) get documents with a current date less than its own interval

Document structure (fields unrelated to this question removed):

{
    _id: ObjectId,
    lastDate: Date,
    interval: Integer, // in seconds
    mode: String
}

What I'm looking for is a query similar to:

{
    lastDate: {
        $lt: new Date() - $interval
    },
    mode: {
        $in: ['collect', 'debug']
    }
}

Therefore the query would get all documents with a lastDate that's less than the current date/time minus its own interval. Also only get documents with mode set to collect or debug.

Can this be done with a basic query or do I need to use aggregate or mapReduce?

Upvotes: 0

Views: 440

Answers (2)

wdberkeley
wdberkeley

Reputation: 11671

Mathematically, your condition is

lastDate < current_time - interval

which is equivalent to

lastDate + interval < current_time

Therefore, instead of (or in addition to) storing lastDate and interval, store their sum. The sum can be stored as seconds since epoch or as a date - you can pick what's most convenient for you in your client code.

Upvotes: 1

iDev247
iDev247

Reputation: 1901

I found a solution but I'm not sure if it's the best one performance-wise.

The query that works:

{
    $where: "this.lastDate < new Date() - this.interval",
    mode: {
        $in: ['collect', 'debug']
    }
}

Uses the $where operation:

Use the $where operator to pass either a string containing a JavaScript expression or a full JavaScript function to the query system. The $where provides greater flexibility, but requires that the database processes the JavaScript expression or function for each document in the collection. Reference the document in the JavaScript expression or function using either this or obj.

Upvotes: 0

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