mongoDB: find by embedded value

Question

I have some problems with mongoDB, i looked for an answer but i couldn't find anything that solves my problem....

db.coders.save( {
'name': 'John', 
'languages' : { 'php':'bad','java':'good','brainfuck':'very bad'} 
});

db.coders.save( {
'name': 'Sarah', 
'languages' : { 'php':'good','java':'bad','brainfuck':'very bad'} 
});

db.coders.save( {
'name': 'Tom', 
'languages' : { 'php':'very good','java':'good','brainfuck':'bad'} 
});

now i want to find any coder that knows any language 'very good'...how?

Salvador Dali · Accepted Answer · 2012-11-10 02:37:36Z

5

You could not find it because it is impossible. None of the search operators works on the schema you provided.

The easiest workaround is to change schema a little bit:

db.coders.save( {
'name': 'John', 
'languages' : [ { n: 'php', v: 'bad'},{n:'java', v: 'good'},{n : 'brainfuck', v: 'very bad'}] 
});

In such a case you can query the data using the following query:

db.coders.find({'languages.v' : 'good'})

answered Nov 10, 2012 at 2:37

Salvador Dali

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Everton Yoshitani · Accepted Answer · 2012-11-10 06:18:40Z

2

I agree with Salvador, that changing the schema is better.

But I found that you can search using the $where operator.

db.coders.find({ $where : function() { for(lang in this.languages) { if (this.languages[lang] == 'very good') { return true; }  } return false;  }});

It might be a bit slowly as pointed in the docs.

http://www.mongodb.org/display/DOCS/Advanced+Queries#AdvancedQueries-JavascriptExpressionsand%7B%7B%24where%7D%7D

answered Nov 10, 2012 at 6:18

Everton Yoshitani

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