Service Catalog variable attributes

  • Release version: Yokohama
  • Updated January 30, 2025
  • 3 minutes to read
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    Summary of Service Catalog variable attributes

    ServiceNow’s Service Catalog variables support specific attributes that define their behavior and restrictions. These attributes are configured in theVariable attributesfield on the Type Specifications tab of the Catalog variable form. Multiple attributes can be added by separating them with commas, and multiple values for an attribute are separated by semicolons. If this field is not visible, customers must enable the related UI policyShow attributes when Type is One of Certain Values.

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    Note that pre-selected values on variables using attributes or reference qualifiers do not clear automatically when dependent variable values change; customers should create client scripts to handle clearing values based on their needs.

    Key Attributes and Their Use Cases

    • allowedextensions: Restricts allowed file types on Attachment variables (e.g., txt, pdf).
    • barcode: Enables barcode scanning via mobile camera for Single Line Text variables.
    • maxfilesize: Defines the maximum file size in MB for Attachment variables.
    • glidelist: Changes the List collector interface from slushbucket to glide list.
    • issearchablechoice: For Lookup select box and Select box variables, enables searching and selecting choices; note this is not supported in Service Portal.
    • maxlength: Limits the maximum number of characters for Single-line text and Wide single-line text variables.
    • maxunit: Sets the maximum unit for Duration variables (days, hours, minutes, seconds), affecting display format.
    • nofilter: Hides filter fields above List collector variables.
    • refaccolumns: Specifies columns displayed in auto-completion lists for Reference variables, enhancing search context.
    • refacorderby: Defines sorting column for auto-completion lists in Reference variables.
    • refautocompleter: Determines the JavaScript class used for client-side auto-completion behavior in Reference variables, with options like AJAXReferenceCompleter and AJAXTableCompleter.
    • refqualelements: Lists fields sent to the server to update references dynamically, applicable to Lookup multiple choice, Lookup select box, and List Collector variables.

    Practical Importance for ServiceNow Customers

    By leveraging these variable attributes, customers can tailor catalog items to enforce data input restrictions, improve user experience with searchable and filtered selections, and customize file and duration inputs. These attributes enable finer control over catalog variable behavior, ensuring data quality and streamlining request fulfillment.

    When configuring catalog variables, customers should also consider creating client scripts to manage dependent variable behaviors not handled automatically by attributes.

    There are a few Service Catalog variables support specific attributes to define the behavior and restrictions for variables.

    In the Catalog variable form, under the Type Specifications tab, you can specify the variable attributes in the Variable attributes field.

    Note:
    • You can enter multiple attributes for a variable type by separating each with a comma.
    • You can enter multiple values for an attribute by separating each with a semicolon.
    • If you don't see the Variable attributes field, enable the Show attributes when Type is One of Certain Values UI policy.
    • Pre-selected values are not cleared automatically when the dependent variable value changes when using an attribute or reference qualifier. Create a client script to clear the values based on your needs and the needs of your customer.

    Variable attributes

    allowed_extensions

    Specifies a list of allowed file types. For example, allowed_extensions=txt;pdf.

    Applicable variables: Attachment
    barcode

    Specifies if the barcode can be scanned using the mobile camera for identifying a variable value of a catalog item. For example, barcode=true.

    Applicable variables: Single Line Text
    max_file_size

    Specifies the maximum file size in MB. For example, max_file_size=2.

    Applicable variables: Attachment
    glide_list

    Changes the list collector interface from slushbucket to glide list.

    Applicable variables: List collector
    Figure 1. Collapsed glide_list
    Screenshot for the glide_list attribute when collapsed
    Figure 2. Expanded glide_list
    Screenshot for the glide_list attribute when expanded
    is_searchable_choice

    If set to true, enables you to search for and select the required value for the variable. For example, is_searchable_choice=true.

    Note:
    • For Lookup select box, a default value is available at the page load itself.
    • This attribute is not applicable in Service Portal.
    Applicable variables: Lookup select box, Select box
    Figure 3. is_searchable_choice
    Screenshot for the is_searchable_choice attribute
    max_length

    Sets the maximum number of characters allowed in the field. By default, the field accepts long strings of text, several thousand characters. Set the max_length attribute as appropriate for the information that the variable is collecting. For example, to allow for entry of an address, set max_length=200, or other appropriate length.

    Applicable variables: Single-line text, Wide single-line text
    max_unit

    Sets the maximum unit of time for the duration. Possible values are max_unit=days,max_unit=hours,max_unit=minutes, and max_unit=seconds.

    For example, if max_unit=minutes, the duration is displayed in minutes and seconds. In this case, a duration of 2 days 3 hours 5 minutes 15 seconds is displayed as 3065 minutes 15 seconds.

    Applicable variables: Duration
    no_filter

    Hides the filter fields that appear above a list collector.

    Applicable variables: List collector
    Figure 4. no_filter
    Screenshot for the no_filter attribute
    ref_ac_columns
    Specifies the columns with display values that appear in an auto-completion list in addition to the name. Separate column names with a semicolon. For example, ref_ac_columns=user_name;email;sys_created_on allows auto-complete to match text from the user_name, email, and sys_created_on columns.

    Applicable variables: Reference, Requested For.

    ref_ac_order_by

    Specifies the column that is used to sort the auto-completion list. For example, ref_ac_order_by=name sorts the auto-completion choices alphabetically by name.

    Applicable variables: Reference
    ref_auto_completer

    Specifies the name of a JavaScript class (client-side) that creates the list for auto-completion choices. Valid class values include:

    • AJAXReferenceCompleter: Displays matching auto-complete choices as a drop-down list. The list only displays the display value column of the reference table. If there is no other auto-completion class specified, reference fields automatically use this class.
    • AJAXTableCompleter: Displays matching auto-complete choices as rows in a table. The table displays the display value column of the reference table and any columns listed in the ref_ac_columns attribute.
    • AJAXReferenceChoice: Displays matching auto-complete choices as a drop-down list. The list only displays the display value column of the reference table. The list only displays up to 25 matching choices. If there are more than 25 auto-complete choices, the reference field instead displays the choices with the AJAXTableCompleter class.
    Applicable variables: Reference
    ref_qual_elements

    A list of fields to be sent back to the server to get an updated reference.

    Applicable variables: Lookup multiple choice, Lookup select box, List Collector.
    Important:
    Attribute behavior is specific to the service catalog desktop.