CODEWITHSUNDEEP
mongodbupdatesmongodb-.net-driver
lotus_misser
lotus_misser

Reputation: 135

mongodb update with many embedd document

guys, I use official CSharp Driver of mongodb, I got these two classes:

public class A
{
    public A()
    {
        Bs = new List<B>();
    }

    [BsonId]
    public string Id { get; set; }
    public string Name { get; set; }
    public IList<B> Bs { get; set; }
}

public class B
{
    public string Name { get; set; }
}

in db, B is embedd in A document, entity is an object of A, then do the saving job like this:

collection.Save<A>(entity);

the Save method will perform either insert or update depends on the Id, my question is: when i do collection.Save(entity) the second time, that means entity document already exists in the A collection, does every fields in A and B document got updated? I dont know how the driver handler this kind of thing. supposed there ara a lot of B objects, let say 100 of them and not modified. what process going on?

Upvotes: 0

Views: 121

Answers (1)

Sergey Gavruk
Sergey Gavruk

Reputation: 3568

When you call Save, base on your [BsonId] field driver decides what to do with this document:

  • if document with Id does not exist in collection, it will insert this document
  • if document with Id exists in collection, it will update this document (based on your Id). Update means it will replace all fields with the new fields from your entity

Here is an example how save method works in pseudocode (the same as in C# driver):

   function save( doc ) {
      if( doc["_id"] ) {
         update( {_id: doc["_id"] }, doc, { upsert: true } );
      }
      else {
         insert(doc);
      }
   }

Upvotes: 1

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