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Regex Slots are user-defined Slots, which apply regular expressions (regex) to match and extract specific patterns from user inputs. Unlike Lexicon Slots, which rely on Keyphrases, Regex Slots are ideal for structured data that follows a predictable format, such as:
  • Phone numbers ((123) 456-7890)
  • Email addresses (user@example.com)
  • Product codes (ABC-123-XYZ)
You can use this type of Regex Slots only as Slot Fillers.

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Recommendations

  • Regex Slots require careful crafting to avoid overly broad or restrictive patterns.
  • Complex regular expressions can be error-prone; test them thoroughly to avoid missing matches or capturing incorrect data.
  • Avoid conflicts with Lexicon Slots and System Slots by ensuring unique Slot names.

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Working with Regex Slots

To start working with Regex Slots, you can use one of the following options:
To define a regex pattern that runs on all user inputs in the Flow, follow these steps:
  1. In the Flow editor, go to NLU > Slot Fillers.
  2. In the upper-left corner, click + New Slot Filler.
  3. In the New Slot Filler window, fill in the following fields:
    • Name – enter a unique name for the Slot Filler. For example, phone_number.
    • Type – select Regular Expression.
    • Regular Expression – enter a regex pattern. Patterns must start and end with /. Flags like g for global matching aren’t supported.
    • Context Key – enter a Slot name to store the matched data in the Context object. For example, phone_number.

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Example

These examples show how regex patterns fill Slots in the Context object.
User Input: My phone number is 555-123-4567
Regex Pattern: /\d{3}-\d{3}-\d{4}/
Slot Name: phone_number
Result: The context.phone_number Slot is filled with 555-123-4567. The AI Agent responds Thanks for providing your phone number: {{context.slots.phone_number}}!
When the user input contains multiple values that match the pattern, only the first match is stored.User Input: The booking codes are 123456 and 789123
Regex Pattern: /\b\d{6}\b/
Slot Name: booking_codes
Result: The context.booking_codes Slot is filled with 123456.

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Use Cases

  • Extracting a booking code: /^[A-Z]{3}-\d{4}$/ to capture XYZ-1234.
  • Capturing email addresses with the @company domain: /^[a-zA-Z0-9._%+-]+@company\.com$/.
  • Identifying dates in specific formats: /^\d{2}\/\d{2}\/\d{4}$/ for 04/22/2025.

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More Information