A String Constraint filter provides a way to filter data on the client using a set of predetermined String values. These String values are called Constraints and can be generated from unique values in the underlying data. This approach allows an end-user to see a dropdown of values that are known to be present in the data.

Create a String Constraint Filter

To create a String Constraint Filter, perform the following steps:

1. Log in to edgeCore as an administrator.
2. Open a Page in Edit Mode.
3. Above the Visualization in which you want to add the filter, click the gear button to show the options drop-down menu.
4. Select “Edit Filters”.
5. On the “Manage Client Filters” dialog, click + to add a new filter.
6. On the “Select Client Filter” dialog, click + Add to show the selection list.
7. Click to select “String Constraint Filter”.

Add and Edit a String Constraint Filter

String Constraint Filters can be reused across different datasets. The only thing required for a String Constraint Filter is a list of valid values that can be used as input. This is the same Constraint concept that is used with server variables. Since Constraints are defined globally, any constraint already defined for use with variables can be reused for client filters as well, and visa-versa. The example below shows a String Constraint that will provide a list of valid Company Names which will be presented as a dropdown.

An Unconstrained String Filter

If an administrator does not want to limit input, then they can use the system-provided Unbounded String option. This will result in a text field input instead of a dropdown and will allow end-users to type whatever they want, similar to the Search Field client filter.

Applying a String Constraint Client Filter

Applying a String Constraint Filter involves selecting an attribute. It is essentially a mapping exercise. The Attribute to Filter property should contain values that have some relationship to the Constraints defined in the String Constraint Filter. For example:

• Constraints are derived from an Attribute containing names of National Parks.
• The String Constraint Filter would be applied to a dataset that has an attribute with National Parks.

String Constraint Properties

Example String Filter

The default value for a String Filter is All, which shows all records.