CODEWITHSUNDEEP
rubymongodbmongoid
Martin
Martin

Reputation: 121

how to query the key exists in mongoid or mongo(ruby)

{"_id":{"$oid":"5ee9e17e88adc3a1d6c2a39f"},"title":"test","products":{"car":"yes hello"}}

how can I query the documents which have the key car use mongo _id or mongo? I tried

    irb(main):042:0> x = client[:materials].find({"products.car":{$exists=>true}})
=> #<Mongo::Collection::View:0x47269370736460 namespace='db.materials' @filter={"products.car"=>{nil=>true}} @options={}>
irb(main):043:0> x.count
Traceback (most recent call last):
        1: from (irb):43
BSON::InvalidKey (NilClass instances are not allowed as keys in a BSON document.)

and I don't know how to do it with mongo _id or mongo. and puzzled about the error message

Upvotes: 0

Views: 1556

Answers (2)

Andrew
Andrew

Reputation: 77

You do need to quote the $exists, but you also are not using the right search method. The method .find expects a document id, but you are passing it a query string.

If you only want the first record that matches your query, use:

.find_by("products.car":{"$exists"=>true})

If you want all records that match your query, use:

.where("products.car":{"$exists"=>true})

Upvotes: 1

D. SM
D. SM

Reputation: 14520

{$exists=>true}

This references the global variable $exists. Try:

{"$exists"=>true}

Upvotes: 0

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