Transactions and WithDatabase

[cskardon]

This is quite a big one:

• This allows Transactions in both the GraphClient and BoltGraphClient
• Transactions are started from the ITransactionalGraphClient interface, which is now easily accessible via the Tx property on an IGraphClient

using (var tx = client.Tx.BeginTransaction()){
  //Transaction stuff here

  await tx.CommitAsync();
  await tx.RollbackAsync();
}

NB if you're using a using and don't call CommitAsync it will RollbackAsync as part of the Dispose of the transaction.

• Transactions can be against a particular database:

using (var tx = client.Tx.BeginTransaction(TransactionScopeOption.Join, null, "my-db"))
{ 
  /* Stuff here */ 
}

Attempting to run a query inside the transaction against another database will throw an InvalidOperationException - transactions can only be against one database.

NB - I know this is a clunky way of doing this - we're still in pre-release, but expect this signature to change.

• DefaultDatabase has been added and is set on the client when instantiating. This is overridden by use of WithDatabase. This only affects connections to a 4.x database - it will do nothing on a 3.x one. If not set, this defaults to neo4j

//The 'case' of the DefaultDatabase will be 'ToLower'd as Neo4j only has lowercase database names
var client = new BoltGraphClient("neo4j://localhost:7687", "neo4j", "neo") {DefaultDatabase = "neo4jclient"};

• WithDatabase has been added to the ICypherFluentQuery interface

await client.Cypher
    //WithDatabase here overrides 'DefaultDatabase'
    .WithDatabase("my-db")
    .Match("(n)")
    .Return(n => n.Count())
    .ResultsAsync;

• All executions are now against the Transaction API for the GraphClient version