转SSIS 2012 pass values from child package to parent with project deployment model

http://stackoverflow.com/questions/20288766/ssis-2012-pass-values-from-child-package-to-parent-with-project-deployment-model

Parameter binding on the execute package task is currently a ONE way street Parent --> Child.

Here is a way to pass a value from a child package variable to a parent package variable.

Script Task: (in child package)

// Populate collection of variables.
// This will include parent package variables.
Variables vars = null;
Dts.VariableDispenser.GetVariables(ref vars);

// Lock the to and from variables.
Dts.VariableDispenser.LockForWrite("User::MyParentPackageVar");
Dts.VariableDispenser.LockForRead("User::MyChildPackageVar");

// Apparently need to call GetVariables again after locking them.
// Not sure why - perhaps to get a clean post-lock set of values.
Dts.VariableDispenser.GetVariables(ref vars);
vars["User::MyParentPackageVar"].Value = vars["User::MyChildPackageVar"].Value;

vars.Unlock();

This code was actually from a pre-2012 SSIS Package that I just finished upgrading to SSIS for SQL Server 2012 (in Visual Studio 2012), and converted to project deployment model.

Initially, the execution died (after a lengthy delay) on the variable assignment line. But then I added the "User::" prefix, which apparently was necessary for at least one, but not all of the variables I was assigning this way. The prefix was not necessary in SSIS for SQL Server 2008.