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I'm trying to query my database for prices greater than/less than a user specified number. In my database, prices are stored like so:
{price: "300.00"} According to the docs, this should work:
db.products.find({price: {$gt:30.00}}).pretty() But I get no results returned. I've also tried {price: {$gt:30}}.
What am I missing here?
It it because the prices are stored as a string rather than a number in the DB? Is there a way around this?
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Comparison Operators Matches if values are greater than the given value. $lt. Matches if values are less than the given value. $gte. Matches if values are greater or equal to the given value.
Definition. $gt selects those documents where the value of the field is greater than (i.e. > ) the specified value . For most data types, comparison operators only perform comparisons on fields where the BSON type matches the query value's type. MongoDB supports limited cross-BSON comparison through Type Bracketing.
As for the logical condition, there are String Aggregation Operators that you can use $strLenCP operator to check the length of the string. If the length is $gt a specified value, then this is a true match and the document is "kept".
For comparison of different BSON type values, see the specified BSON comparison order. If the field holds an array, then the $in operator selects the documents whose field holds an array that contains at least one element that matches a value in the specified array (for example, <value1> , <value2> , and so on).
If you intend to use $gt with strings, you will have to use regex, which is not great in terms of performance. It is easier to just create a new field which holds the number value of price or change this field type to int/double. A javascript version should also work, like so:
db.products.find("this.price > 30.00") as js will convert it to number before use. However, indexes won't work on this query.
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