dataStore.startTransaction( )

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4D v19.8


	dataStore.startTransaction ()

	Does not require any parameters

Description

The dataStore.startTransaction( ) method starts a transaction in the current process on the database matching the datastore to which it applies. Any changes made to the datastore's entities in the transaction's process are temporarily stored until the transaction is either validated or cancelled.

Note: If this method is called on the main datastore (i.e. the datastore returned by the ds command), the transaction is applied to all operations performed on the main datastore and on the underlying database, thus including ORDA and classic languages.

You can nest several transactions (sub-transactions). Each transaction or sub-transaction must eventually be cancelled or validated. Note that if the main transaction is cancelled, all of its sub-transactions are also cancelled even if they were validated individually using the dataStore.validateTransaction( ) method.

Example

 C_OBJECT($connect;$ds;$person;$status)

 C_TEXT($choice)

 C_BOOLEAN($error)

 

 Case of

    :($choice="local")

       $ds:=ds

    :($choice="remote")

       $connect:=New object("hostname";"111.222.3.4:8044")

       $ds:=Open datastore($connect;"myRemoteDS")

 End case

 

 $ds.startTransaction()

 $person:=$ds.Persons.query("lastname=:1";"Peters").first()

 

 If($person#Null)

    $person.lastname:="Smith"

    $status:=$person.save()

 End if

 ...

 ...

 If($error)

    $ds.cancelTransaction()

 Else

    $ds.validateTransaction()

 End if