Dynamic Package Configurations (Part 2)


This article continue discussion about a method of dynamically assigning variable values at runtime Apply the Record Set to Applicable Variables

Initial State

The initial states of the string variables are set to C:\ with variables being used for the record set container.

The code in the Show Values script tasks is simple and only there to demonstrate a variable values. This is the same code for all three ‘Show Value’ scripts. Note that the variables are passed to the script via the default ReadOnlyVaraibles inputs for the script task.

Assign the Record Sets to the variables (Object Container)

The Execute SQL tasks (‘Get Params (1)’ and ‘Get Params (2)’) are used to pass the query to a container. The queries are not complicated (below) and the standard methods for assigning a record set to a variable apply. These are to ensure that the result set is set to ‘Full Result Set’

Query for Each Result Set

Assign Result Set to Variable

There are two requirements to assign the result set to a variable. Firstly ensure that the result set is set to ‘Full Result Set’ and secondly, that the variable is mapped to the result set.

The two script tasks (‘Assign Params (1)’ and ‘Assign Params (2)’) both contain the same code and only expose the record set variable. One of the main benefits of this technique is that the assignment script does not need to know ahead of time what variables are going to be assigned. This is deemed by the field ‘variable_name’ in the record set result.

There are two main pieces of code in this script task. Firstly, we assign the record set variable (variables) to a data table (in order to iterate over it) and secondly, we iterate over the table and assign variable a value.

Assign the Record Set to a Data Table

The code to assign the record set to the data table is below.

Assigning the Dataset To Variables

The code to assign the data table to variables is below. The iteration of data table (rows) shouldn’t be too much of an issue here or should the checking for package variable name but the key takeaways are that we

  1. Check to see that the variable exists (using VariableDespenser.Contains)
  2. Lock the variable (VariableDespenser.LockForOneWrite)
  3. and then write the value.

Benefits

There are other methods of variable assignment that can be used to change the value of variables at run time, for example, we could assign values in a execute SQL task based on a single row. However, I think that limitation with an approach like this is that task has to be configured ahead of time and the variable names must be known. This method allows variable assignment based solely on the passed record set and as such is very reusable.

I should also point out that this example assumes a sting data type. The code can be extended to permits user defined data types so the record set specifies the data type however this was not included for brevity.

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