Node.JS + MongoDB aggregation Find array in array from DataBase in MongoDB - arrays

Question

I have a Model in MongoDB which include an array(category) which has an array(picture) inside it.
Shirt Model looks like this:
{ _id: 100, category: [ { name: 'CatName', _id: 101, picture: [Object] } ] }
And my Picture Array looks like this:
[ { path: 'p1', _id: 102 },
{ path: 'p2', _id: 103 } ] }
I Pass 3 variables
main array id which is 100 (var1)
category name which is CatName (var2)
picture id which is 102 (var3)
I want to GET an array which looks like:
{ _id: 100, category: [ { name: 'CatName', _id: 101,
picture: [ { path: 'p1', _id: 102 }]
} ]
}
What I have tried is this:
Shirt.find( {_id: var1} ,
{category: { $and:[ { name: var2 } , { picture: {$elemMatch: {_id: var3}}} ] }} )
.exec(function(err, product) {
console.log('Result ' + product );
res.jsonp(product);
});
But the Result I receive is Undefined for First Code
Second Code That I tried:
Shirt.find( {_id: var1} ,
{category: {$elemMatch: { name: var2,picture: {$elemMatch: {_id: var3} }}} } )
And Result from second code filter the array for var1 and var2
But it contain the whole picture array which means it does not filter var3
What is the correct code to find what I want?
Is this a correct approach for a Shopping Website database Or you have a better suggestion?
Am I applying Parent and Child Database Correctly?
Thanks!

Answer 1

Following mongo query will give you expected result:
db.collection.find({
"category": {
$elemMatch: {
"name": "CatName",
"picture": {
$elemMatch: {
"_id": 102
}
}
}
}
})
You need to convert it in node.js format.
Following format may help you. Not Tested
collection.find({
_id: "" // add your match Id here} ,
{
category: {
"$elemMatch": {
"name": "CatName",
"picture": {
$elemMatch: {
"_id": 102
}
}
}
}
}
})
.exec(function(err, product) {
console.log('Result ' + product);
res.jsonp(product);
});
AFTER EDIT QUESTION
You should use mongo aggregation to get required values. Query will be like following -
db.collection.aggregate({
$unwind: '$category'
}, {
$unwind: '$category.picture'
}, {
$match: {
_id: 100, // add here your var1 variable instead of 100
'category.name': 'CatName', // add here your var2 variable instead of 'CatName'
'category._id': 102, //add your match id here if any otherwise remove this condition
'category.picture._id': 102 //add your var3 instead of 102
}
}, {
$group: {
_id: '$category.name',
'name': {
$first: '$category.name'
},
'picture': {
'$push': '$category.picture'
}
}
})