Search within list of objects in mongodb using morphia

Question

I am very new to Java. I am very new to mongoDB.

I have a collection that looks something like this:

{
    "_id" : "1234",
    "name" : "bill",
    "products" : [ 
        {
            "fooType" : "bar",
            .....
        },
        {
            "fooType" : "oof",
            .....
        }        
    ],
    "status" : "Truncated"
},
{...}

I am trying to implement a search feature to search by fooType. I am able to create a working query using standard mongodb syntax, but cannot figure out how to implement using morphia.

A working mongodb query :

db.Clients.find({products: {$elemMatch: {fooType: "bar"}}})

Some (truncated) code that I've tried without any success:

DatastoreImpl ds;
q = ds.createQuery(Clients.class).field("products").hasThisElement("fooType");

Obviously this doesn't work because it expects an object. I can't seem to wrap my head around how to use hasThisElement, and I'm not even sure if that's the best way to go about this anymore.

Answer 1

hasThisElement expects an object in the parameter, so you couldn't use a String "fooType" or “bar”.

Assume that you have the following classes for this collection:

class Clients {
String id;
String name;
List<Product> products = new ArrayList<Product>();
String status;
}

class Product {
String fooType;
....
}

To use $elemMatch, you would need to create an object for the filter on products as below, and use this filter object in hasThisElement():

Product filterProduct = new Product();
filterProduct.fooType = "bar";
Query q = ds.createQuery(Clients.class).field("products").hasThisElement(filterProduct);