MongoDB DateTime Format

Question

In mongodb adhoc query, before executing the query, how to format the date type element to dd\\mm\\yyyy format and then execute the query?

Answer 1

If you are using Java, you can create Date objects from strings using the parse method of the DateFormat class.

The Java documentation on the DateFormat Class may be found here: http://docs.oracle.com/javase/1.4.2/docs/api/java/text/DateFormat.html

The specific section on the parse method is here: http://docs.oracle.com/javase/1.4.2/docs/api/java/text/DateFormat.html#parse%28java.lang.String%29

The Java documentation on the Date object may be found here: http://docs.oracle.com/javase/1.4.2/docs/api/java/util/Date.html As per the "Constructor Summary" section, the ability to pass a string into the constructor is "Deprecated. As of JDK version 1.1, replaced by DateFormat.parse(String s)."

While I was researching the above, I also came across the Calendar class, which may be used for converting a Date object and a set of integers. It may not be necessary for this application, but I thought it might be useful to include a link to the documentation: http://docs.oracle.com/javase/1.4.2/docs/api/java/util/Calendar.html

Integers for year, month, day, hour, etcetera may be passed in via the set method: http://docs.oracle.com/javase/1.4.2/docs/api/java/util/Calendar.html#set%28int,%20int,%20int,%20int,%20int%29

By way of example, here is a short Java Program that creates a number of Date objects, stores them in a Mongo collection, and then executes a query similar to what you have described. Hopefully it will help you to accomplish your goal. NOTE: This program drops a collection named "dates", so be sure to change the collection name if you already have such a collection in your database!

public static void main(String[] args) throws UnknownHostException, MongoException {
    Mongo m = new Mongo( "localhost:27017" );
    DB db = m.getDB("test");

    DBCollection coll = db.getCollection("dates");
    coll.drop();

    DateFormat df = DateFormat.getInstance();
    String dateString = new String();
    Date myDate = new Date();
    // Save some test documents
    for(int i=1; i<11; i++){
        dateString = "04/" + String.valueOf(i) + "/12 11:00 AM, EST";
        BasicDBObject myObj = new BasicDBObject("_id", i);
        try {
            myDate = df.parse(dateString);
        } catch (ParseException e) {
            e.printStackTrace();
        }
        myObj.put("date", myDate);
        System.out.println(myDate);
        coll.save(myObj);
    }

    // Build the query 
    Date startDate = new Date();
    Date endDate = new Date();
    try {
        startDate = df.parse("04/4/12 11:00 AM, EST");
        endDate = df.parse("04/6/12 11:00 AM, EST");
    } catch (ParseException e) {
        e.printStackTrace();
    }
    BasicDBObject dateQuery = new BasicDBObject();
    dateQuery.put("$gte", startDate);
    dateQuery.put("$lte", endDate);

    System.out.println("---------------");
    //Execute the query
    DBCursor myCursor  = coll.find(new BasicDBObject("date", dateQuery));

    //Print the results
    while(myCursor.hasNext()){
        System.out.println(myCursor.next().toString());
    }
}