MongoDB: query within document - mongodb

Question

I have my mongodb document like this...
{
"semantics" : [
{
"text": "abc gave payment to xyz",
"action": "gave"
},
{
"text": "abc wanted quicker solution",
"action": "want"
}
],
"keyword" : [
{
"word":"payment",
"imp":0.91
},
{
"word":"solution",
"imp":0.7
}
]
}
The requirement is to find action values for those words whose importance is more than 0.9.
In the above case, payment has importance more than 0.9 and, hence, should be considered. payment exists in one of the array and the action value in it is gave.
I am requesting help in constructing mongodb query for the same.

Answer 1

You can first use mapReduce:
db.collection.mapReduce(
function() {
for (var i = 0; i < this.keyword.length; i++) {
if (this.keyword[i].imp >= 0.9) {
emit(this.keyword[i].word, this.semantics)
}
}
},
function(key, values) { },
{
out: {merge: 'result'},
finalize: function(key, semantics) {
var result;
for (var i = 0; i < semantics.length; i++) {
if (semantics[i].text.indexOf(key) != -1) {
result = {key: semantics[i].action};
}
}
return result;
}
)
We don't care about the reduce function here since map will return {word with imp >= 0.9: the whole semantics}.
Later, before storing the result into result collection, finialize function is called and it goes through all semantics associated with a word and fetches all actions related to texts that contain the key word.
After this, you can db.result.find() to see the result, you will see some null result because not all key has a matched text and action, you need to clean up a bit.