I am using the below mentioned MongoDB query in Java to find the maximun value of field price:
DBCursor cursor = coll.find(query,fields).sort(new BasicDBObject("price",1)).limit(1);
fields argument passing to coll.find function here is having the price field only.
So I am getting the output in the form:
{"price" : value}
Is there any way to get value only in the output without the field name and braces etc, so that it can be assigned to a variable or returned to the calling function etc.
Or if there is any other query or mechanism available that I can use for the same purpose.
Pls suggest..
Thanks & Regards
You can get value of price from the DBCursor object as follows.
while (cursor.hasNext()) {
Double price = (Double) cursor.next().get("price");
}
On the mongo shell you can do it as follows :
db.priceObj.find({},{_id:0, price:1}).sort({price:-1}).limit(1)[0].price
You cannot do this due to the fact that MongoDB communicates using BSON.
A single value like you want would be invalid BSON. It is easy enough to filter it out your side.
Related
I went through the documentation of Java api to query Grakn database.
Grakn.Transaction readTransaction = session.transaction(GraknTxType.READ);
GetQuery query = Graql.match(var("p").isa("person")).limit(10).get();
Stream<ConceptMap> answers = query.withTx(readTransaction).stream();
answers.forEach(answer -> System.out.println(answer.get("p").id()));
It's printing id, but I want to see the data, the name associated with the person. I want to see the content inside the result. It's simply showing id.
The answers provided as the result of a Graql query, is a collection of the variables (and their values) as you have specified them in the query itself.
In this case, to get the name of instances of person, you'd include it in the query like so:
GetQuery query = Graql.match(var("p").isa("person").has("name", var("n"))).limit(10).get();
The Graql equivalent being match $p isa person, has name $n; get;.
Now you can use the methods available in the Concept API to retrieve information available on each variable.
In this case, variable n holds an attribute and you'd want to retrieve its value(), like so:
answers.forEach(answer -> System.out.println(answer.get("n").asAttribute().value()))
I am using latest version of GreenDAO... I am missing something on using the data from the DB.
I need to prevent the creation of records that have the same PROFILE_NUMBER. Currently during testing I have inserted 1 record with the PROFILE_NUMBER of 1.
I need someone to show me an example of how to obtain the actual value of the field from the db.
I am using this
SvecPoleDao svecPoleDao = daoSession.getSvecPoleDao();
List poles = svecPoleDao.queryBuilder().where(SvecPoleDao.Properties.Profile_number.eq(1)).list();
and it obtains something... this.
[com.example.bobby.poleattachmenttest2_workingdatabase.db.SvecPole#bfe830c3.2]
Is this serialized? The actual value I am looking for here is 1.
Here is the solution.You'll need to use listlazy() instead of list().
List<SvecPole> poles = svecPoleDao.queryBuilder().where(SvecPoleDao.Properties.Profile_number.eq(1)).listLazy();
I have mongodb aggregation query and it works perfectly in shell.
How can i rewrite this query to use with morphia ?
org.mongodb.morphia.aggregation.Group.addToSet(String field) accepts only one field name but i need to add object to the set.
Query:
......aggregate([
{$group:
{"_id":"$subjectHash",
"authors":{$addToSet:"$fromAddress.address"},
---->> "messageDataSet":{$addToSet:{"sentDate":"$sentDate","messageId":"$_id"}},
"messageCount":{$sum:1}}},
{$sort:{....}},
{$limit:10},
{$skip:0}
])
Java code:
AggregationPipeline aggregationPipeline = myDatastore.createAggregation(Message.class)
.group("subjectHash",
grouping("authors", addToSet("fromAddress.address")),
--------??????------>> grouping("messageDataSet", ???????),
grouping("messageCount", new Accumulator("$sum", 1))
).sort(...)).limit(...).skip(...);
That's currently not supported but if you'll file an issue I'd be happy to include that in an upcoming release.
Thanks for your answer, I can guess that according to source code. :(
I don't want to use spring-data or java-driver directly (for this project) so I changed my document representation.
Added messageDataSet object which contains sentDate and messageId (and some other nested objects) (these values become duplicated in a document which is a bad design).
Aggregation becomes : "messageDataSet":{$addToSet:"$messageDataSet"},
and Java code is: grouping("messageDataSet", addToSet("messageDataSet")),
This works with moprhia. Thanks.
I have been trying to retrieve information from querying a specific Asset(Story/Defect) on V1 using the VersionOne.SDK.Java.APIClient. I have been able to retrieve information like ID.Number, Status.Name but not Requests.Custom_SFDCChangeReqID2 under a Story or a Defect.
I check the metadata for:
https://.../Story?xsl=api.xsl
https://.../meta.V1/Defect?xsl=api.xsl
https://.../meta.V1/Request?xsl=api.xsl
And the naming and information looks right.
Here is my code:
IAssetType type = metaModel.getAssetType("Story");
IAttributeDefinition requestCRIDAttribute = type.getAttributeDefinition("Requests.Custom_SFDCChangeReqID2");
IAttributeDefinition idNumberAttribute = type.getAttributeDefinition("ID.Number")
Query query = new Query(type);
query.getSelection().add(requestCRIDAttribute);
query.getSelection().add(idNumberAttribute);
Asset[] results = v1Api.retrieve(query).getAssets();
String RequestCRID= result.getAttribute(requestCRIDAttribute).getValue().toString();
String IdNumber= result.getAttribute(idNumberAttribute).getValue().toString();
At this point, I can get some values for ID.Number but I am not able to retrieving any information for the value Custom_SFDCChangeReqID2.
When I run the restful query to retrieve information using a browser from a server standpoint it works and it does retrieve the information I am looking for. I used this syntax:
https://.../rest-1.v1/Data/Story?sel=Number,ID,Story.Requests.Custom_SFDCChangeReqID2,Story.
Alex: Remember that Results is an array of Asset´s, so I guess you should be accessing the information using something like
String RequestCRID= results[0].getAttribute(requestCRIDAttribute).getValue().toString();
String IdNumber= results[0].getAttribute(idNumberAttribute).getValue().toString();
or Iterate through the array.
Also notice that you have defined:
Asset[] results and not result
Hi thanks for your answer! I completely forgot about representing the loop, I was too focus on the retriving information part, yes I was actually using a loop and yes I created a temporary variable to check what I was getting from the query in the form
Because I was getting the variables one by one so I was only using the first record. My code works after all. It was just that What I was querying didn't contain any information of my use, that's why I was not finding any. Anyway thanks for your comment and observations
I've been struggling with queries with Google's datastore and wanted to get some help.
I have a form that saves a double to the datastore. Here is a snippet from the servlet:
String temp = req.getParameter("temp");
message.setProperty("temp", temp);
temp is a string but containes a number with decimal places.
In my JSP code I'm trying to run the query:
query.addFilter("temp",Query.FilterOperator.GREATER_THAN, -0.9);
But it only seems to work if the value (-0.9) is an integer (-1). Also, when I try to use a variable I get an invalid constant error:
query.addFilter("temp",Query.FilterOperator.GREATER_THAN, request.getParameter('mintemp'));
Any help would be appreciated!
Thanks!
Chance are you are setting your property as a String, you should store the property as a Float instead see the documentation for setProperty.
Convert your String to a Float before setting the Entity property:
message.setProperty("temp", Float.parseFloat(temp));