Hello all,
I'm trying to use the new implementation of the Mongo Aggregation framework by Spring Data team I'm using the spring-data version 1.3.0.RC1 ! and for reference I'm looking at https://jira.springsource.org/browse/DATAMONGO-586
Here is my problem:
Let's say we have collections with article items:
How I can make an aggregation query like this:
db.articles.aggregate( {$project:{author:1, comments:1}} , {$unwind:"$comments"} , {$sort:{"comments.createdAt":-1}} , {$group: {_id:null,comments:{$push:"$comments"}}} );
I try with the following code snippet but every time exceptions are thrown:
I want to transform articles collection to be displayed only with comments ordered by "createdAt" field.
I don't know if my approach is wrong or the aggregation framework is not yet fully implemented.
Thanks in advance
I'm trying to use the new implementation of the Mongo Aggregation framework by Spring Data team I'm using the spring-data version 1.3.0.RC1 ! and for reference I'm looking at https://jira.springsource.org/browse/DATAMONGO-586
Here is my problem:
Let's say we have collections with article items:
Code:
{
"_id": {
"$oid": "5214b5d529ee12460939e2ba"
},
"title": "this is my title",
"author": "bob",
"pageViews": 5,
"tags": [
"fun",
"sport"
],
"comments": [
{
"author": "alex",
"text": "this is cool",
"createdAt": 1
},
{
"author": "sam",
"text": "this is bad",
"createdAt": 2
},
{
"author": "jenny",
"text": "this is bad",
"createdAt": 3
}
],
"other": {
"foo": 5
}
}
.....db.articles.aggregate( {$project:{author:1, comments:1}} , {$unwind:"$comments"} , {$sort:{"comments.createdAt":-1}} , {$group: {_id:null,comments:{$push:"$comments"}}} );
I try with the following code snippet but every time exceptions are thrown:
Code:
Aggregation agg = newAggregation( //
project().andInclude("author").andInclude("comments"), //this should make the project part : {$project:{author:1, comments:1}} - actual result: { "comments" : "$comments" , "author" : "$author"}
unwind("comments"),//second part : {$unwind:"$comments"} - this is correct
group("_id","comments").push("comments").as("comments") - throws invalid reference "_id"...
//sort(Direction.ASC,"comments.createdAt") - this didn't work with nested array properties
);I don't know if my approach is wrong or the aggregation framework is not yet fully implemented.
Thanks in advance