CODEWITHSUNDEEP
c#.netmongodbmongodb-querymongodb-.net-driver
Waxren
Waxren

Reputation: 2172

Create multiple indexes in a transaction using C# Mongodb strongly typed driver

I am using the official C# MongoDb strongly typed driver version 2.7.0-beta0001 to interact with MongoDB.

What I am trying to do is to create multiple indexes in a single transaction but I always get "Message "Object reference not set to an instance of an object".

Even if I didn't use the transactions by removing the session variable, I also get the same exception.

Here is my code:

var client = new MongoClient(ConnectionString);

var database = client.GetDatabase(DatabaseName);

var Coupons = database.GetCollection<Coupon>("Coupons");

var Books = database.GetCollection<Book>("Books");

var session = await database.Client.StartSessionAsync();
session.StartTransaction();

try {

     var options = new CreateIndexOptions() { Unique = true };

     var couponIndex = new IndexKeysDefinitionBuilder<Coupon>().Ascending(c => c.CouponNumber);
     var couponIndexModel = new CreateIndexModel<Coupon>(couponIndex, options);
     await Coupons.Indexes.CreateOneAsync(session, couponIndexModel);//Exception happens at this line

     var bookIndex = new IndexKeysDefinitionBuilder<Book>().Ascending(c => c.BookNumber);
     var bookIndexModel = new CreateIndexModel<Book>(bookIndex, options);
     await Books.Indexes.CreateOneAsync(session, bookIndexModel);

     await session.CommitTransactionAsync();
} catch (Exception ex) {
     await session.AbortTransactionAsync();

     Console.WriteLine(ex.StackTrace);
}

Here are the exception details:-

Message "Object reference not set to an instance of an object."

Source  "MongoDB.Driver"

StackTrace  "at MongoDB.Driver.MongoIndexManagerBase`1.ToCreateManyIndexesOptions(CreateOneIndexOptions options)
at MongoDB.Driver.MongoIndexManagerBase`1.CreateOneAsync(IClientSessionHandle session, CreateIndexModel`1 model, CreateOneIndexOptions options, CancellationToken cancellationToken)

TargetSite  {MongoDB.Driver.CreateManyIndexesOptions ToCreateManyIndexesOptions(MongoDB.Driver.CreateOneIndexOptions)}  System.Reflection.MethodBase {System.Reflection.RuntimeMethodInfo}

{System.NullReferenceException: Object reference not set to an instance of an object.
at MongoDB.Driver.MongoIndexManagerBase`1.ToCreateManyIndexesOptions(CreateOneIndexOptions options)
at MongoDB.Driver.MongoIndexManagerBase`1.CreateOneAsync(IClientSessionHandle session, CreateIndexModel`1 model, CreateOneIndexOptions options, CancellationToken cancellationToken)

Upvotes: 0

Views: 1801

Answers (1)

Wan B.
Wan B.

Reputation: 18835

What I am trying to do is to create multiple indexes in a single transaction

Operations that affect the database catalog, such as creating or dropping a collection or an index, are not allowed in multi-document transactions.

See also MongoDB Transactions and CRUD Operations for more information.

MongoDB commands supported in transactions are:

Upvotes: 2

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