db_transaction (public)

 db_transaction [ -dbn dbn ] transaction_code [ args... ]

Defined in packages/acs-tcl/tcl/01-database-procs.tcl

Usage: db_transaction transaction_code [ on_error { error_code_block } ] Executes transaction_code with transactional semantics. This means that either all of the database commands within transaction_code are committed to the database or none of them are. Multiple db_transactions may be nested (end transaction is transparently ns_db dml'ed when the outermost transaction completes).

To handle errors, use db_transaction {transaction_code} on_error {error_code_block}. Any error generated in transaction_code will be caught automatically and process control will transfer to error_code_block with a variable errmsg set. The error_code block can then clean up after the error, such as presenting a usable error message to the user. Following the execution of error_code_block the transaction will be aborted. If you want to explicitly abort the transaction, call db_abort_transaction from within the transaction_code block or the error_code block.

Example 1:
In this example, db_dml triggers an error, so control passes to the on_error block which prints a readable error.

    db_transaction {
        db_dml test "nonsense"
    } on_error {
        ad_return_error "Error in blah/foo/bar" "The error was: $errmsg"
    }
    

Example 2:
In this example, the second command, "nonsense" triggers an error. There is no on_error block, so the transaction is immediately halted and aborted.

    db_transaction {
        db_dml test {insert into footest values(1)}
        nonsense
        db_dml test {insert into footest values(2)}
    }
    

Switches:

-dbn (optional)

The database name to use. If empty_string, uses the default database.

Parameters:

transaction_code (required)

Partial Call Graph (max 5 caller/called nodes):

Testcases:

db__transaction, db__transaction_bug_3440