Java best way to parse MongoDB file

Question

So, I read my MongoDB this way:

        mongo = new MongoClient("localhost", 27017);
        // Accessing the database
        MongoDatabase database = mongo.getDatabase("myDb");
        MongoCollection<Document> collection = database.getCollection("searchresults");

        // Getting the iterable object
        FindIterable<Document> iterDoc = collection.find();
        int i = 1;

        // Getting the iterator
        Iterator it = iterDoc.iterator();

        while (it.hasNext()) {
            System.out.println(it.next());
            i++;
        }
    }

As you can see, each line has several columns: Title, etc. So, when I iterate over myDB, i want to parse each line by its value instead of get all in one line.

Any suggestions?

So the question is how to read a result rather than actually parsing a file? A hint: You're already looping over your results in your while loop. Put your it.next() call into a Document variable and see what kind of getters you can call on it. You can use that to investigate how to retrieve the data you need. — Stefan
– Stefan, Commented Sep 18, 2018 at 11:41
If you declare your iterator with generics by using Iterator<Document>, Java will see that a Document instance is expected when it.next() is called. — Stefan
– Stefan, Commented Sep 18, 2018 at 12:41

mdewit · Accepted Answer · 2018-09-18 11:59:58Z

2

You can try reading into a Document structure, then run another loop across each of the entries. This will give each value on its own line.

FindIterable<Document> iterDoc = database.getCollection("").find();
for(Document doc : iterDoc) {
    for(Map.Entry<String, Object> entry : doc.entrySet()) {
        System.out.println("Key: " + entry.getKey() + " Value: " + entry.getValue());
    }
}

If you only want certain keys, use a projection in your find query

edited Sep 18, 2018 at 11:59

answered Sep 18, 2018 at 11:51

mdewit

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Comments

Steffen · Accepted Answer · 2018-09-18 11:48:56Z

0

This is not a fitting answer to your question, but i would look in to a concept thats called Object-Document-Mapping (ODM). It simplifies some boilerplate code that you have to care about. A common library for MongoDB-ODM is called Morphia :)

answered Sep 18, 2018 at 11:48

Steffen

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2 Comments

danny kob Over a year ago

So i did not understand what i have to do

Steffen Over a year ago

You can use it.next() to iterate to the document entrySet. But i would use morphia :) just an advice

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