First, let me say that I am a novice so may not ask this question as clearly as it could have been asked. here goes
From java I am calling a function FindName(int,string) (snippet below), I am getting the JSONParser errors on the DBObject ref statement. The code works fine if I hardcode the value pairs, but the goal is for the calling routine to pass different values and get the correct result.
The values being passed are valid, I even println to verify the values.
The issue seems to be that even though the values are valid int and string that mongodb does not seem to allow you to specify the names of the values that are passed to this function in the key-value pairs.
Therefore I am guessing that you need to transform the date, name values that are passed in, to a format that is acceptable to the key-value pair. The question is how to do that.
static String FindName(int date, String name)
MongoClient mongoClient;
try {
mongoClient = new MongoClient("xxx.xx.xx.xxx",27017);
}
catch (UnknownHostException e)
{
e.printStackTrace();
return name;
}
DB db = mongoClient.getDB("tpfdf");
DBCollection PNR = db.getCollection("PNR");
DBObject ref = (DBObject) JSON.parse("{PnrByDateFlightCustom: {date: date), pname: name'}}");
at com.mongodb.util.JSONParser.parse(JSON.java:208)
at com.mongodb.util.JSONParser.parseObject(JSON.java:241)
at com.mongodb.util.JSONParser.parse(JSON.java:205)
at com.mongodb.util.JSONParser.parseObject(JSON.java:241)
at com.mongodb.util.JSONParser.parse(JSON.java:205)
at com.mongodb.util.JSONParser.parse(JSON.java:155)
at com.mongodb.util.JSON.parse(JSON.java:93)
at com.mongodb.util.JSON.parse(JSON.java:74)
at MongoDB5.locatePassengerName(MongoDB5.java:38)
at MongoDB5.main(MongoDB5.java:11)
Update. After many trial and errors, I found that if you dynamically build the string and then execute the ref with the dynamic string, it works.
This worked. I do not know if this is the correct way to code this, but this works so will go with it for now.
String mdbStr = "{PnrByDateCustom: {date:" + value + "}}";
System.out.println("mdbStr = " + mdbStr);
DB db = mongoClient.getDB("tpfdf");
DBCollection PNR = db.getCollection("PNR");
DBObject ref = (DBObject) JSON.parse("{}");
// ref = (DBObject) JSON.parse("{PnrByDateCustom: {date: value} }" );
ref = (DBObject) JSON.parse(mdbStr);
Related
Here is my query that attempts to sort an array of MongoDB documents based on a derived field called expiresAt. expiresAt is a Date object that represents the date string stored in doc.expirationDate.
It fails with an error TypeError: ... .sort({}) is not a function (shell):5
db.tokens.find().map(function(doc) {
var expiryDate = new Date(doc.credentialsMap.linkedin.expirationDate);
doc.expiresAt = expiryDate;
return doc;
}).sort({'expiresAt': -1});
What am I doing wrong? It's unclear to me exactly what return type map provides. If it's a cursor then why isn't sort supported? It's clearly available in the docs.
cursor.map() returns a Java script array.
The way you're calling sort() assumes that the return value is a MongoDB cursor, that's why it fails.
You'd have to use the regular Array.sort syntax.
For example, to have your map results sorted in descending order, use the following:
db.tokens.find().map(function(doc) {
var expiryDate = new Date(doc.credentialsMap.linkedin.expirationDate);
doc.expiresAt = expiryDate;
return doc;
}).sort(function(a,b) { return b.expiresAt - a.expiresAt});
Im trying to learn how to make sql like queries in Mongo and found this aggregation framework, when i run the code the average always turns out "0" all though the 'columns' have numbers in them, if i understand it right mongoDB saves all values as a strings( the number where integers at first in my sql server database which i transferred to mongoDB) so i dont have to care about types really when working with MongoDB? Can someone see why my average function dont work? The ordered quantity has number between 1.000000 - 7.000000.
DBCollection order = db.getCollection("Orderstatus");
DBObject match = new BasicDBObject("$match", new BasicDBObject("Company", "100") );
DBObject fields = new BasicDBObject("Facility", 1);
fields.put("Ordered quantity", 1);
fields.put("_id", 0);
DBObject project = new BasicDBObject("$project", fields );
DBObject groupFields = new BasicDBObject( "_id", "$Facility");
groupFields.put("average", new BasicDBObject( "$avg", "$Ordered quantity"));
DBObject group = new BasicDBObject("$group", groupFields);
AggregationOutput output = order.aggregate( match, project,group );
System.out.println(output);
The thing is that i thought that the numbers would be as integers since i got them from my sql server database where they are stored as integers using the code below. I see now that i use getString() when getting the values, is that why the numbers are strings in mongodb? how can i get them as integers?? i really want to be able to manipulate them as numbers!
StringBuilder orderstatus = new StringBuilder();
orderstatus.append("SELECT * FROM dbo.fact_orderstatus");
PreparedStatement t = connect.prepareStatement(orderstatus.toString());
DBCollection orderstat = db.getCollection("Orderstatus");
ResultSet v = t.executeQuery();
ResultSetMetaData rsm = t.getMetaData();
int column = rsm.getColumnCount();
while (v.next()) {
BasicDBObject orderObj = new BasicDBObject();
for(int x=1; x<column +1; x++){
String namn= rsm.getColumnName(x);
String custNum = (v.getString(x));
if (custNum != null && !custNum.trim().isEmpty()
&& custNum.length() != 0)
orderObj.append(namn, custNum);
}
orderstat.insert(orderObj)
The reason this is happening is that MongoDB does care about types of values you save.
If you want to store numbers, make sure they are not quoted otherwise they become stored as strings and you lose ability to manipulate them as numbers.
Javascript also differentiates between numbers and string, but MongoDB supports more number types than simple JavaScript. You can read more here.
I need to use findAndModify in my application with grails and mongoDB.
I used this code :
public static String getNextId(DB db, String seq_name) {
String sequence_collection = "seq"; // the name of the sequence collection
String sequence_field = "seq"; // the name of the field which holds the sequence
DBCollection seq = db.getCollection(sequence_collection); // get the collection (this will create it if needed)
// this object represents your "query", its analogous to a WHERE clause in SQL
DBObject query = new BasicDBObject();
query.put("_id", seq_name); // where _id = the input sequence name
// this object represents the "update" or the SET blah=blah in SQL
DBObject change = new BasicDBObject(sequence_field, 1);
DBObject update = new BasicDBObject("$inc", change); // the $inc here is a mongodb command for increment
// Atomically updates the sequence field and returns the value for you
DBObject res = seq.findAndModify(query, new BasicDBObject(), new BasicDBObject(), false, update, true, true);
return res.get(sequence_field).toString();
}
and it work successful. But now I want use findAndModify without native mongodb object, and with using GORM.
Is there any solution for this work?
There is not way to accomplish this without native API, you can however write your code a bit more compact like this:
def collection = Seq.collection
collection.findAndModify([_id: seq_name ], [ "\$inc": [seq:1] ])
Config your DataSource.groovy with db configurations.
Then define a Domain class:
Class Seq{
int seq
}
And use dynamic finder in a sevice:
Class SeqService {
String findAndModify(String seq_name) {
def seqInstance = Seq.get(seq_name)
if(seqInstance){
seqInstance.seq ++
seqInstance.save()
return seqInstance.seq.toString()
}
return '' //instance not found
}
}
Then make a call when you need that action:
def seqService
def id
.......
def result = seqService.findAndModify(id)
....
i have this code for removing an item froma a mongofb collation
private MongoCollection<T> GetCollection()
{
connectionString = "mongodb://localhost/?safe=true";
server = MongoServer.Create(connectionString);
database = server.GetDatabase("CSCatalog");
return database.GetCollection<T>("myCollectionName");
}
public bool Delete(T entity)
{
var id = typeof(T).GetProperty("Id").GetValue(entity,null).ToString();
var query = Query.EQ("_id",id);
var finded = GetCollection().Find(query); // return null
var result= GetCollection().Remove(query, MongoDB.Driver.RemoveFlags.Single); // no errors, but don't remove
return esito.Ok; //return true but donn't remove.
}
the GetCollection() method retrive the right collection, i have tested it width debug.
In the collection there is the item that i want remove, it have the same id that i have retrived in first line.
the entity have some fields and a Objectid filed called "Id"
the type of _id you created is ObjectId class and you are trying to equate with string so its not able to remove. use
var queryId = new ObjectId(id);
Your finded variable should not be null if the .find() has returned something from your database. That it is null means that you have not found anything, and therefore nothing is to be removed.
What it looks like is happening here is that you are querying on _id for the ObjectId, while you are storing that ObjectId in the database as Id.
I'm trying to execute a query from java against a Map/Reduce view I have created on the CouchDB.
My map function looks like the following:
function(doc) {
if(doc.type == 'SPECIFIC_DOC_TYPE_NAME' && doc.userID){
for(var g in doc.groupList){
emit([doc.userID,doc.groupList[g].name],1);
}
}
}
and Reduce function:
function (key, values, rereduce) {
return sum(values);
}
The view seems to be working when executed from the Futon interface (without keys specified though).
What I'm trying to do is to count number of some doc types belonging to a single group. I want to query that view using 'userID' and name of the group as a keys.
I'm using Ektorp library for managing CouchDB data, if I execute this query without keys it returns the scalar value, otherwise it just prints an error saying that for reduce query group=true must be specified.
I have tried the following:
ViewQuery query = createQuery("some_doc_name");
List<String> keys = new ArrayList<String>();
keys.add(grupaName);
keys.add(uzytkownikID);
query.group(true);
query.groupLevel(2);
query.dbPath(db.path());
query.designDocId(stdDesignDocumentId);
query.keys(keys);
ViewResult r = db.queryView(query);
return r.getRows().get(0).getValueAsInt();
above example works without 'keys' specified.
I have other queries working with ComplexKey like eg:
ComplexKey key = ComplexKey.of(userID);
return queryView("list_by_userID",key);
but this returns only a list of type T (List) - using CouchDbRepositorySupport of course - and cannot be used with reduce type queries (from what I know).
Is there any way to execute the query with reduce function specified and a complex key with 2 or more values using Ektorp library? Any examples highly appreciated.
Ok, I've found the solution using trial and error approach:
public int getNumberOfDocsAssigned(String userID, String groupName) {
ViewQuery query = createQuery("list_by_userID")
.group(true)
.dbPath(db.path())
.designDocId(stdDesignDocumentId)
.key(new String[]{userID,groupName});
ViewResult r = db.queryView(query);
return r.getRows().get(0).getValueAsInt();
}
So, the point is to send the complex key (not keys) actually as a single (but complex) key containing the String array, for some reason method '.keys(...)' didn't work for me (it takes a Collection as an argument). (for explanation on difference between .key() and .keys() see Hendy's answer)
This method counts all documents assigned to the specific user (specified by 'userID') and specific group (specified by 'groupName').
Hope that helps anybody executing map/reduce queries for retrieving scalar values from CouchDB using Ektorp query.
Addition to Kris's answer:
Note that ViewQuery.keys() is used when you want to query for documents matching a set of keys, not for finding document(s) with a complex key.
Like Kris's answer, the following samples will get document(s) matching the specified key (not "keys")
viewQuery.key("hello"); // simple key
viewQuery.key(documentSlug); // simple key
viewQuery.key(new String[] { userID, groupName }); // complex key, using array
viewQuery.key(ComplexKey.of(userID, groupName)); // complex key, using ComplexKey
The following samples, on the other hand, will get document(s) matching the specified keys, where each key may be either a simple key or a complex key:
// simple key: in essence, same as using .key()
viewQuery.keys(ImmutableSet.of("hello"));
viewQuery.keys(ImmutableSet.of(documentSlug1));
// simple keys
viewQuery.keys(ImmutableSet.of("hello", "world"));
viewQuery.keys(ImmutableSet.of(documentSlug1, documentSlug2));
// complex key: in essence, same as using .key()
viewQuery.keys(ImmutableSet.of(
new String[] { "hello", "world" } ));
viewQuery.keys(ImmutableSet.of(
new String[] { userID1, groupName1 } ));
// complex keys
viewQuery.keys(ImmutableSet.of(
new String[] { "hello", "world" },
new String[] { "Mary", "Jane" } ));
viewQuery.keys(ImmutableSet.of(
new String[] { userID1, groupName1 },
new String[] { userID2, groupName2 } ));
// a simple key and a complex key. while technically possible,
// I don't think anybody actually does this
viewQuery.keys(ImmutableSet.of(
"hello",
new String[] { "Mary", "Jane" } ));
Note: ImmutableSet.of() is from guava library.
new Object[] { ... } seems to have same behavior as ComplexKey.of( ... )
Also, there are startKey() and endKey() for querying using partial key.
To send an empty object {}, use ComplexKey.emptyObject(). (only useful for partial key querying)