Since I’ve been given the opportunity to play with K2
smartforms, I’ve constructed quite a few scenarios, each of which aimed at a
specific area (or component) within the product.
This week I decided to target the Expression builder, in
order to test whether the component could handle complex functions, and if they
passed, if it made a noticeable impact on performance.
For this implementation, I built a tax calculator,
incorporating the various tax brackets we have in South Africa. The different
brackets, and their respective tax calculations, are represented by the below
spread sheet:
|
0
< 160000 Tax
= (Salary * 0.18) - Rebate
|
|
160000 < 250000 Tax = (28000 + 0.25*(Salary - 160000)) -
Rebate
|
|
250000 < 346000 Tax = (51300 + 0.3*(Salary - 250000)) -
Rebate
|
|
346000 < 484000 Tax = (80100 + 0.35*(Salary - 346000)) -
Rebate
|
|
484000 < 617000 Tax = (128400 + 0.38*(Salary - 484000))
- Rebate
|
|
617000 >= Tax = (178940 + 0.4*(Salary - 617000)) -
Rebate
|
This can be calculated by means of the following console
app:
using System;
public class TaxCalc
{
static void Main()
{
Console.Write("Enter your yearly salary: ");
string
input = Console.ReadLine();
decimal
mySalary = Convert.ToDecimal(input);
decimal
myTax = 0.0m;
if
((mySalary > 0) & (mySalary <= 160000))
{
myTax = (0.18m * mySalary) - 11440;
}
else if ((mySalary > 160000) & (mySalary <=
250000))
{
myTax = (28000 + 0.25m * (mySalary
- 160000)) - 11440;
}
else if ((mySalary > 250000) & (mySalary <=
346000))
{
myTax = (51300 + 0.3m * (mySalary -
250000)) - 11440;
}
else if ((mySalary > 346000) & (mySalary <=
484000))
{
myTax = (80100 + 0.35m * (mySalary
- 346000)) - 11440;
}
else if ((mySalary > 484000) & (mySalary <=
617000))
{
myTax = (128400 + 0.38m * (mySalary
- 484000)) - 11440;
}
else
{
myTax = (178940 + 0.4m * (mySalary
- 617000)) - 11440;
}
Console.WriteLine("Your yearly tax is: {0}", myTax);
Console.ReadKey();
}
}
Using K2 smartforms, I created a Form which looked as
follows:
The Forms consists of:
·
An Item View – which is used to enter and
capture new salary line items
·
A List View – which is used to display all
previously captured items
·
Various Form-level [Label] and [DataLabel]
controls, used to do the various calculations
I started with a basic Rule to transfer the data from the
Item- to the List View. The List View contains a [Sum] aggregation on the
“Value” column, which is hidden in this instance. From here I simply transfer
the value of this hidden aggregation, to the “Monthly Income [DataLabel]” from
there the actual calculations start. The value of the “Monthly Income
[DataLabel]” is multiplied by twelve and transferred to the “Yearly Income
[DataLabel]”.
Once I have this value, I execute a rather complex nested
“IF” inline function, in order to determine the appropriate bracket, and the
yearly tax thereof. A simple example of the expression would look something
like this:
IF ((mySalary > 0) &
(mySalary <=160000), 0.18*mySalary, (IF ((mySalary > 160000) &
(mySalary <= 250000), 28000 + 0.25*(mySalary - 160000), IF ((mySalary >
250000) & (mySalary <= 346000), 51300 + 0.3*(mySalary – 250000), etc…
Here’s a screenshot of the actual Expression:
I used various other simple expressions in order to
calculate the monthly tax, and both Nett Income amounts (including null checks,
validation etc.)
In my test I found that the runtime execution of the
Expression via K2 smartforms was both accurate and immediate from the user
perspective.
Here is a comparison between the results from K2
smartforms and the console application:
[Console]
[K2 smartforms]
On a side note, I initially created this Expression on
two controls in an Item View just in order to test the functionality. Only
afterwards, I decided that I wanted to try this in the above pictured scenario.
The problem was though, that the Expression now resided on a View which I did
not want to use in my scenario.
As a workaround, I created the above Form, complete with everything except this complex Expression. I then used ‘Firebug’ to determine the GUID of the control to which I wanted to point the Expression (as the Expression only uses a single ‘source’ control in order to execute). The next step was to query the K2 smartforms DB’s, and extract my expression which was saved in XML format in the [Form].[View_Design].
Once I had the extracted XML, I could replace the old
GUID’s with the GUID of the new control. I then simply ran an update script
against my Form in the [Forms].[Form_Design] table to inject my Expression into
the new Form, bound the Expression to a new ‘destination’ control, and presto!
