MongoDB C++ Update array and add element

Question

I want to update the "user"-array of the following JSON-document which is saved in a MongoDB Database (programming language C++)

{
        "_id" : ObjectId("5ac4beacc0e2a512e6377d43"),
        "document" : "test",
        "user" : [
            {
                "email" : "[email protected]",
                "username" : "Anton Held",
                "job" : "",
            },
            {
                "email" : "[email protected]",
                "username" : "Benny Bill",
                "job" : "IT-Officer",
            },
            {
                "email" : "[email protected]",
                "username" : "Conny Cenn",
                "job" : "",
            },
        ]
    }

Therefore I am using this command to get this specific document:

collection.update_one(document{} << "document" << "test"
                                     << finalize,
                      document{} << "$set" << open_document <<
                                 (HOW TO DEAL?!) close_document << finalize);

I know that it is possible to update a document with the "update_one"-method (or similar methods like "replace_one", "find_one_and_replace").

But I don't know how to deal with this methods to update as example the username of the existing user with the "email"-element="[email protected]" or how I could add a user to the existing array "user".

Please help me :-)

Okay that works with this command, but i am not able to convert this to C++: db.getCollection('testcollection').update({"document":"test", "user.email":"[email protected]"}, {"$set": {"user.$.username":"New Username"}}) Please take a look at my last example :collection.update_one(document{} << "document" << "test" << finalize, document{} << "$set" << open_document << (HOW TO DEAL?!) close_document << finalize); — Fabi Held
– Fabi Held, Commented Apr 8, 2018 at 10:26

rustyx · Accepted Answer · 2018-04-08 11:46:31Z

2

So you question boils down to how to convert this mongo command to C++ code:

db.getCollection("testcollection").update(
   {"document":"test", "user.email":"[email protected]"},
   {"$set": {"user.$.username":"New Username"}}
)

Here's how it can look like. Notice the pattern:

Output keys and values in pairs
Use open_document and close_document for nested { and }

Sample result:

collection.update_one(
  document{} << "document" << "test"
             << "user.email" << "[email protected]"
             << finalize,
  document{} << "$set"
             << open_document
                 << "user.$.username" << "New Username"
             << close_document << finalize
);

answered Apr 8, 2018 at 11:46

rustyx

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Comments

Coral Kashri · Accepted Answer · 2020-12-19 15:29:25Z

As the documentation says, you can do as follow to add a new user:

db.getCollection("testcollection").update(
   { "document": "test"},
   { "$push": {
         "user": {
             "username":"A new user in town ;)",
             "email": "[email protected]"
             "job": "A cool job for a cool user"
         }
     }
   }
)

In mongodbcxx:

As @rustyx mentioned you can simply change {} to open/close document and to get:

collection.update_one(
  document{}
      << "document" << "test"
      << finalize,

  document{}
      << "$push" << open_document
          << "user" << open_document
              << "username" << "A new user in town ;)"
              << "email"    << "[email protected]"
              << "job"      << "A cool job for a cool user"
          << close_document
      << close_document
      << finalize
);

BTW, I would recommend to replace "user" array name to "users", because it's users array and not a user array.

Fabi Held · Accepted Answer · 2018-04-08 10:59:27Z

-1

Okay that works with this command, but i am not able to convert this to C++:

db.getCollection('testcollection').update({"document":"test", "user.email":"[email protected]"}, {"$set": {"user.$.username":"New Username"}})

Please take a look at my last example where I try to figure out how to update this special element "username" of the user with email="[email protected]":

collection.update_one(document{} << "document" << "test" << finalize, 
                      document{} << "$set" << open_document << 
                      (HOW TO DEAL?!) close_document << finalize);

edited Apr 8, 2018 at 10:59

answered Apr 8, 2018 at 10:32

Fabi Held

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1 Comment

rustyx Over a year ago

This is not an answer. Use the edit button on the question and add it to the question itself. Then delete this answer.

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