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So I have an embedded document that tracks group memberships. Each embedded document has an ID pointing to the group in another collection, a start date, and an optional expire date.
I want to query for current members of a group. "Current" means the start time is less than the current time, and the expire time is greater than the current time OR null.
This conditional query is totally blocking me up. I could do it by running two queries and merging the results, but that seems ugly and requires loading in all results at once. Or I could default the expire time to some arbitrary date in the far future, but that seems even uglier and potentially brittle. In SQL I'd just express it with "(expires >= Now()) OR (expires IS NULL)" -- but I don't know how to do that in Mongo.
Any ideas? Thanks very much in advance.
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In MongoDB, we can apply the multiple conditions using the and operator. By applying the and operation we will select all the documents that satisfy all the condition expressions. We can use this operator in methods like find(), update() , etc as per the requirement.
Find Multiple Conditions Using the $or Operator The or operator in MongoDB is used to select or retrieve only documents that match at least one of the provided phrases. You can also use this operator in a method like a find() , update() , etc., as per the requirements.
MongoDB provides the find() that is used to find multiple values or documents from the collection. The find() method returns a cursor of the result set and prints all the documents. To find the multiple values, we can use the aggregation operations that are provided by MongoDB itself.
MongoDB provides different types of logical query operators and $and operator is one of them. This operator is used to perform logical AND operation on the array of one or more expressions and select or retrieve only those documents that match all the given expression in the array.
Just thought I'd update in-case anyone stumbles across this page in the future. As of 1.5.3, mongo now supports a real $or operator: http://www.mongodb.org/display/DOCS/Advanced+Queries#AdvancedQueries-%24or
Your query of "(expires >= Now()) OR (expires IS NULL)" can now be rendered as:
{$or: [{expires: {$gte: new Date()}}, {expires: null}]} If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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