Question

I have a document collection like this:

{
    "_id" : ObjectId("4fb21439f31dfd122ce39c4a"),
    "Name" : "Freelander 2",
    "Manufacture" : "Landrover"
}

I am using the C# driver, and want to check whether the “Name” field exists; if it does not, I need to update it from the code. Can someone help on this? Please share sample code because I am a newbie to mongoDB.

Answer 1

You can use the exists operator:

db.myCollection.find( { Name: { $exists: true } } );

Using the C# driver, the equivalent would be something like this:

IMongoQuery query = Query.Exists("Name", true)
var results = myCollection.Find(query);

To set a value if it doesn’t exist, you can use an Update statement like this:

IMongoQuery query = Query.Exists("name", true);
IMongoUpdate update = Update.Set("Name", "newvalue");
myCollection.Update(query, update);