MongoDB - add nested arrays using Java

Question

I'm trying to add an array of "discountList" inside of an array of "simulatedProducts" using Java to populate a MongoDB collection. However, they are being added separetely, and I'm not sure how I can write this so that discountList is populated inside the simulatedProducts.

Can someone please help me with this?

This is the code (inside a for each):

DBCollection collection = database1.getCollection("wallet");

document.put("ID", id);

BasicDBObject document = new BasicDBObject();

collection.insert(document);

DBObject listItem = new BasicDBObject();
BasicDBObject pushOnProduct = new BasicDBObject();
for (Product produto : wallet.getSimulation().getFutureProductList()){
   listItem = new BasicDBObject("simulatedProduct", new BasicDBObject
                               ("name",produto.getName()).append("minimum",produto.getMinumum()).append[...]);

pushOnProduct.put("$push", listItem);
collection.update(document, pushOnProduct,true,true);

for(Discount discount: produto.getDiscountList()){
    listItem = new BasicDBObject("discountList", new BasicDBObject
                ("nameDiscount",discount.getNameDiscount()).append("percentage",discount.getPercentage()));

    pushOnProduct.put("$push", listItem);
    collection.update(document, pushOnProduct,true,true);
 }

Returned result that is added on the collection:

{
    "simulatedProduct": [{
            "name": "X",
            "minimum": 1000
        }, {
            "name": "Test",
            "minimum": 2380
        }, "discountList": [{
            "nameDiscount": "Tax",
            "percentage": 3
        }, {
            "nameDiscount": "Something",
            "percentage": 3
        }]
    }
}

Expected result:

{
    "simulatedProduct": [{
            "name": "X",
            "minimum": 1000,
            "discountList": [{
                "nameDiscount": "Tax",
                "percentage": 3
            }, {
                "nameDiscount": "Something",
                "percentage": 3
            }]
        }, {
            "name": "Test",
            "minimum": 2380
        }, "discountList"
    }
}

Can you add little bit more code ? What is the value for document field ? Why not just do one update ? — s7vr
– s7vr, Commented Jun 10, 2017 at 21:55
Added more code. I do a second update because I want to push another list into the product of the first list, so I need it to be there before the push. — Gabriel Missel Gonçalves
– Gabriel Missel Gonçalves, Commented Jun 10, 2017 at 22:38

s7vr · Accepted Answer · 2017-06-11 21:42:40Z

1

You can refactor the code.

The below code will iterate one product at a time, create an update document with setting name, minimum and push discountList and add the update document to the productList.

You can run the update query with the productList to push the entire simulatedProduct array.

Something like

 BasicDBList productList = new BasicDBList();
 for (Product produto : wallet.getSimulation().getFutureProductList()) {
    BasicDBList discountList = new BasicDBList();
    for (Discount discount : produto.getDiscountList()) {
       discountList.add(new BasicDBObject("nameDiscount", discount.getNameDiscount()).append("percentage", discount.getPercentage()));
    }
    productList.add(new BasicDBObject("name", produto.getName()).append("minimum", produto.getMinimun()).append("discountList", discountList));
 }
 DBObject update = new BasicDBObject("$push", new BasicDBObject("simulatedProduct", productList));
 collection.update(document, update, true,true);

edited Jun 11, 2017 at 21:42

answered Jun 10, 2017 at 23:31

s7vr

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2 Comments

Gabriel Missel Gonçalves Over a year ago

Looks like it doesn't recognize "$push", it's giving me "Invalid BSON field name $push" at this line: DBObject update = new BasicDBObject("simulatedProduct", new BasicDBObject("$push", productList));

s7vr Over a year ago

Updated to include the document instead of key value pairs and change the order of the key and push modifier.

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