Create a rule

How to access it? 

"Channels" tab > select a channel > "settings"

Use conditions/rules to optimize your catalogue values at every step of your products setting in Lengow and before sending them to a channel :

  • At the Categories mapping step
  • At the Attributes mapping step
  • At the Exclusions step

The process detailed below is the same for all these steps. 

How to add a new rule

Select the attribute on which you want to apply a rule > clic on the cog icon (see image) to open the rules settings page.

If you are setting up the "Category mapping", click on "I need to split my category" and then, "Add a new condition". More info here.


There is a technical limitation at 50 attributes containing at least one active rule.
Best practice: remember to delete or deactivate your unused rules.

Setting your rule parameters

The setting of a rule in Lengow always follows the same format. Meaning that, to set up a new rule, simply follow the steps below: 

1. Define an action - "I want to"
2. Select the affected products - "For...All my products/Some of my products"
3. Define a time period to apply
4. Rename your rule

Every time you map one of your field with a channel attribute, Lengow considers it as a "Default rule".


Step 1: Define an action

Tell the system what you want to do with this rule.

Several blocks are available to help you define what action to take with this rule. 

I want to...


1.1: Define a value

You can create your own value if you don't have a specific field that works!
  • Use the dollar ($) symbol to call a field from your product catalogue.
  • Directly write the value you want to set.
  • Use a function.

Lengow Tip: Add another action to have an impact on multiple attributes and save time on your settings!


1.2: or Empty values

This action will simply empty the attribute from any catalogue value. You can use this option on a selection of products for example.

It will not erase any value from your catalogue and you can still use them in other attributes.


1.3: or Convert values

It is possible to map the values of a field from your catalog to the expected values requested by a channel.
  • Select the field of your catalog whose values are to be modified
  • The list of values in this field will appear on the left listing
  • All that remains is to link your values with those proposed by the channel OR to enter hard-coded values if no value is proposed by the channel


The conversion list is limited to 500 values. If you need to convert more values, create several rules. 
Example if you have 800 brands to convert: create one rule if the brand contains less than 7 characters, and another one if the brand contains 7 or more characters (to adapt depending on your values).
You can add several actions for the same rule.
This can be used for example to create a rule for your promotions or to empty some fields for parent products only.

Step 2: Select the affected products

Select the products that will be affected by the rule. Two options are possible:

  • All my products: in this case, you just need to click on this option to impact all of your products. 
  • Some of my products: here we invite you to define precisely which products will be affected by creating a condition (When...).


The condition is based on the values of your product catalogue. There are three items to select:

  • The field in your product catalogue where the desired value is located
  • The operator. Two types are available:
    • numeric operators: to be used for your fields containing only numbers (like the price). Your condition can be set by comparing numerical data. Examples : =, >, etc.
    • string operators: for your fields containing text or other alphanumerical data (e.g. SKU). Your condition can be based on the characters present in a field. Examples : Is, Contains, Length=, etc.
  • The target value(s), several cases:
    • You need to refer to a specific value from your product catalogue: Specify this value and note that the case (upper or lower) and spelling must map exactly.
    • You want to target several specific values: Enter these values, one after the other, and separate them using the "pipe" character (|). Example : 3|2|1
    • You want to target all the values from a specific field: call up this field dynamically using the dollar ($) symbol.

By combining these three elements, you can select products from your catalogue.


I want to target the promotional products of my catalogue.
So I define the condition (based on my catalogue) as: When "$standard_price" < "$barred_price"

Then I can also add conditions with the "AND" or "OR" operator:
"AND when my category contains the term Clothes "
"OR when my title contains either Sweater, either Tee-Shirt, either Pants "

You can add several conditions, but keep an eye on the number of affected products!   
The "performance criteria" condition appears only if you have statistical data in Lengow. It will enable you to add a condition over performance such as "clicks > 100 AND revenue is not empty".

Step 3: Define rule during specific period

Choose the period of validity of your rule by checking one of the following options:

  • "all the time" 
  • "over a period" and select the period.
Once the last day has been reached, the rule is automatically deactivated


Step 4: Rename your rule

Automatically and depending on the choices you have made on your rule (the selection of blocks), a title will be added

Example:  Define values / Some of my products / Over a period

You can rename your rule manually, with a more meaningful title by clicking directly on the title or keep the default title.


Priority Order

Rules always take precedence over the default rule applied to all products. In fact, all new rules will be placed above one to another. 

0a850dd1-35f0-46db-8ad4-49e3800c1577.png=> If two or more rules impact the same products, the highest rule will take precedence over the others. Meaning that the last created rule will impact the product in case of a conflict between two or more rules.  

Lengow tip
Consider manually moving your rules in the list to ensure their impact and open the Preview page to check the impact on your feed.    

How does priority work?


1. The default rule is automatically created and saved in the Rules board when an attribute is maped with a value. 100% of the products are immediately impacted. 
- I completed attribute "quantity" with value "10". 
- I maped attribute "quantity" with my field "stock".

2. When a rule is created, it is automatically placed above the default rule. The rate of products covered is immediately re-calculated. 
Example: My rule #1 is impacting 75% of my products. Therefore, my default rule only impacts now 25% of my products.

3. Then, all new rules will be placed above one to another, and the system will re-calculate the rate of products covered.
Example: My rule #1 was impacting 75% of my products. Now that I have added a rule #2, the rate of product covered has been re-calculated. My default rule does not impact any products anymore as my other rules already are impacting 100% of my products.


IMPORTANT: The calculation of the impacted products works as a funnel all the way down to the default rule. The more rules you add, the fewer products may be impacted in the default rule.
Note that the option "Switch to advanced view" enables you to preview your rule without opening it.

Activating/deactivating a rule

On the page listing your rules, you can select one of the options offered on the right of the panel: 

  • Duplicate
  • Disable / Enable
  • Remove 
Duplication adds a new rule to the page, identical to the one selected. This option does not allow you to duplicate the rule to another channel.



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