Business Rule Property previous value

[fundez]

I have a rule that needs to know the previous value of the property it's validating. Is there a way to know the previous value within a business rule?

Thanks,

Mike

[StefanOssendorf]

Hi. Currently not as far as I know.

[Chicagoan2016]

I am not sure if @JasonBock website is still live but he had written about comparing a Property's current value with the previous.

[JasonBock]

My site is back up, but all the old articles are not there (and I don't know if I'll ever get around to doing that). Maybe it's in archive.is somewhere....

[fundez]

It sounds like I need to store the old value and pass it in to the rule. Can I pass public variables to a business rule or only properties?

[Chicagoan2016]

It sounds like I need to store the old value and pass it in to the rule. Can I pass public variables to a business rule or only properties?

I just realized that I have business rule that uses the previous values of the property.
In our case, we just have two properties say CustomerID, PreviousCustomerID and I pass both values to the business rule, with CustomerID being the primary property of the rule.

[Bowman74]

The "cheap" and easy way is to just create a business rule that whenever a property is set it stores the new value into a private property info for the last value. Then you can create a rule to compare the two property infos with the new value and the last value.

You will have to ensure those happen in the correct order so the rule to do the compare logic is called before the rule to set the last value property info with the new value.

[rockfordlhotka]

The "cheap" and easy way is to just create a business rule that whenever a property is set it stores the new value into a private property info for the last value. Then you can create a rule to compare the two property infos with the new value and the last value.

You will have to ensure those happen in the correct order so the rule to do the compare logic is called before the rule to set the last value property info with the new value.

The "expensive" way to do this is to create your own implementation of IFieldData to hold the previous (and maybe original?) value of the field so you can compare those to determine if the field is changed.

There are other types you need to customize to hook this in - which I don't remember off the top of my head. It is fairly complex, because this is a very low-level capability of CSLA.

[fundez]

Sounds like my best bet is to store value in an OldValue Property. Is it possible to have OldValue not trip the dirty flag?

[Chicagoan2016]

I would use one of the property declarations that uses LoadProperty instead of SetProperty. Off the top of my head, read-only property uses LoadProperty

[fundez]

Do you think this will do the trick to store old property not fire validation and not trip dirty flag

public long OldControlNumber
{
get { return GetProperty(OldControlNumberProperty); }
set
{
using (BypassPropertyChecks)
{
LoadProperty(OldControlNumberProperty, value);
}

}

}

[StefanOssendorf]

You don't need (BypassPropertyChecks) with load.

[StefanOssendorf]

And yes this should be sufficient for that. You only need to correctly set the property with the old value

[fundez]

Thank You!