Introduction
In this article, I am going to explain how multiple validations can be applied to a slot in a dialog model of Alexa skill. Slot validation lets you create validation rules for your slot values. Alexa can then check the user's response against these rules and prompt the user if the user provides an unacceptable value.
Slot validation
Slot validation provides an additional dialog model component to help you manage the conversation between your skill and the user. You can configure a set of validation rules for a slot, along with prompts to use for slot values that fail validation.
When the user fills the slot with an utterance and you delegate the dialog to Alexa, Alexa checks the provided value against your rules. If the value fails the validation, Alexa uses your prompts to ask the user for a correct value.
For example, in this dialog, the user is filling a custom Planet slot that only accepts values that match the names of planets in our solar system,
- User - What is the weather like on the sun? (The value the sun is not an acceptable Planet slot value, so Alexa prompts for a new value.)
- Alexa - The Sun is not a planet within our solar system. Please tell me a planet instead.
- User - OK, Mars (The value mars is an acceptable value for a Planet slot.)
- Alexa - On Mars, high of 70 and low of minus 195 fahrenheit. Sunny with a chance of sandstorms later in the day.
To use slot validation,
- Define validation rules and prompts for your slots where needed. These become part of the dialog model for the skill. There are several possible rules for the different types of slots.
- Set up your skill to delegate the dialog to Alexa
Use multiple validation rules for a slot
You can create multiple validation rules for a slot. The rules are checked in the order in which they are shown in the developer console or listed in the JSON. If a value fails a rule, Alexa stops checking and responds with the prompt to correct the value. In a set of multiple rules, a later rule is checked only when all preceding rules have passed.
This means that you can define rules to provide smarter responses depending on the user's mistake. For example, suppose your skill provides facts about planets and uses a custom slot type with the planets of the solar system. You could use a single validation (Accept only Slot type's values and synonyms) to only accept the planet names and provide a generic prompt like "{Planet} is not a planet. Please tell me a planet in our solar system."
However, you know that users might ask about other objects in the solar system that are not planets. Rather than using this generic prompt, you could set up an additional validation to reject these specific values (Reject only a set of values) with a more specific prompt before applying the more generic validation.
For example, you could define these rules for the Planet slot,
Reject only a set of values with the values "the sun", "sun", and "our sun". Prompts,
- "While the sun is part of our solar system, I can only answer this question for planets. Please tell me a planet."
- "We don't think of the sun as having weather, exactly, so please tell me a planet instead."
- (similar prompts showing that Alexa understands the value provided)
Accept only Slot type's values and synonyms. Prompts,
- {Planet} is not a planet. Please tell me a planet in our solar system.
- (similar generic prompts that repeat back the incorrect value).
JSON code for Validation Rules
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