How to update particular array element in MongoDB - mongodb

Question

I am newbie in MongoDB. I have stored data inside mongoDB in below format
"_id" : ObjectId("51d5725c7be2c20819ac8a22"),
"chrom" : "chr22",
"pos" : 17060409,
"information" : [
{
"name" : "Category",
"value" : "3"
},
{
"name" : "INDEL",
"value" : "INDEL"
},
{
"name" : "DP",
"value" : "31"
},
{
"name" : "FORMAT",
"value" : "GT:PL:GQ"
},
{
"name" : "PV4",
"value" : "1,0.21,0.00096,1"
}
],
"sampleID" : "Job1373964150558382243283"
I want to update the value to 11 which has the name as Category.
I have tried below query:
db.VariantEntries.update({$and:[ { "pos" : 117199533} , { "sampleID" : "Job1373964150558382243283"},{"information.name":"Category"}]},{$set:{'information.value':'11'}})
but Mongo replies
can't append to array using string field name [value]
How one can form a query which will update the particular value?

Answer 1

You can use the $ positional operator to identify the first array element to match the query in the update like this:
db.VariantEntries.update({
"pos": 17060409,
"sampleID": "Job1373964150558382243283",
"information.name":"Category"
},{
$set:{'information.$.value':'11'}
})

Answer 2

In MongoDB you can't adress array values this way. So you should change your schema design to:
"information" : {
'category' : 3,
'INDEL' : INDEL
...
}
Then you can adress the single fields in your query:
db.VariantEntries.update(
{
{"pos" : 117199533} ,
{"sampleID" : "Job1373964150558382243283"},
{"information.category":3}
},
{
$set:{'information.category':'11'}
}
)