A powerful part of Sitecore is the business rules engine. Many say it is an underutilized part of the platform. I think part of this is because it is not very well documented. I agree it is a very powerful part of Sitecore so I wanted to spend some time digging in and documenting more about how it works and how to utilize it.
First, let's level set at a high level on what this is. I don't want to rehash the intro stuff as Sitecore documentation does a good job at explaining it at a high level. The documentation that is slim is breaking down how it is configured and how to extend it.
There are a few blogs out there that show quick and dirty examples of how to create custom rules. Before we go there though I want to break down the anatomy of a rule that currently exists. I think this helps level set how a rule comes together. Once we understand its parts it is easier to create our own, and then the power is really unleashed.
In this section is where all the configuration for rules are. If we open "Elements" and then "Device Detection" you will see a conditional rule called "Query string".
In the "Text" field you can see the sentence we saw before when we set up the rule to use. This time though the "value" area has some special syntax around it.
Then in the "Type" field the assembly and class that process this rule is called out.
We know this rule is a conditional rule via two methods. 1) If you look at the "template" field in the top it says it is using the "condition" template. Also, all conditional rules have a diamond icon. Actions will have a rectangle icon.
First, let's level set at a high level on what this is. I don't want to rehash the intro stuff as Sitecore documentation does a good job at explaining it at a high level. The documentation that is slim is breaking down how it is configured and how to extend it.
There are a few blogs out there that show quick and dirty examples of how to create custom rules. Before we go there though I want to break down the anatomy of a rule that currently exists. I think this helps level set how a rule comes together. Once we understand its parts it is easier to create our own, and then the power is really unleashed.
Using a rule
There are many places where a business rule can be created, I will take just one example to work through.
Here we are first, clicking on the default device. Then clicking on the "edit rule" link. This then brings up the "create rule" dialogue with a list of rules (both conditions and actions) we can configure to run. Again, there are a number of places you can access the "create rule" dialogue, this is just one example. For this post, we will be focusing on the "When query string matches value" rule.
In the "edit rule" area you will notice I have selected it and set a value of "my test". You will notice in the choose condition area the word "value" is underlined. This means that field will be replaced with a value (in this case a string) and the condition will execute based on that value.
Where is the rule defined in Sitecore
To start understanding how this rule works we need to dig into how it is set up in Sitecore. To find the above rule we navigate to /sitecore/system/Settings/Rules/Definitions.In this section is where all the configuration for rules are. If we open "Elements" and then "Device Detection" you will see a conditional rule called "Query string".
In the "Text" field you can see the sentence we saw before when we set up the rule to use. This time though the "value" area has some special syntax around it.
Then in the "Type" field the assembly and class that process this rule is called out.
How are they categorized
If you move up the tree just a little you will notice there is an "ElementGroup" node. Under this node is all the groups we can organize our rules into. You can, of course, create a new grouping. Below you will see the rule we have been working with was configured to be in the "Device" group (bottom image). This, in turn, means when you open up the "Create rule" dialogue the rule shows up grouped under "Device".
So now we have seen how these show up in the rules editor based on how they are grouped. But how do we get the grouping we want to show up? This comes down to what you specify in the item template. Below the field "Rule" has a source defined as the Rule Group you want to have show up in the editor.
With the rule source now in place the editor will open up and contain any rules that are part of that rule group. So let's look at the rule groups a bit more now.
This all comes down to what the rule group and the rule is tagged to. You point to the rule field to a rule group. The rule group is linked to certain tags. Those tags are used to find all the rule elements that also have the same tags.
In the image below you can see the tags configured for the group on the top left. Then each rule elements configured tags. If you remember from the first screenshot the rules that show up there. Here is a quick list of them (I left devices off because there is a long list and it is muddy up a little because of secondary tag groups).
Predefined Rules
- where predefined rule is true
Context
- where the current database name compares to value
- where the current device compares to value
- where the current web site name compares to value
Hopefully that helps breakdown and explain some of the organizational and anatomy aspects of Sitecore Business Rules.
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