A container used by Alexa, capable of holding useful piece of information provided by user like Date, Time, City, Country, Fictional Character, Author, Movies, etc.
Source : https://developer.amazon.com/docs/custom-skills/slot-type-reference.html#list-slot-types
Alexa Skills kit supports slot, which are basically containers which are helpful in obtaining specific data which the user has provided in any format to the skill. This input data is useful for the developer to return the necessary response.
For example : Consider you're making a skill which tells you the day of a particular date. More precisely, you give Alexa a date and it returns you the day of the week.
Slots would be useful to obtain the input data Date which the user has specified, and using some logic we can figure out the day for that date.
Consider this conversation:
User: "Alexa launch days of our life"
Alexa: "Welcome to the days of our life". // "days of our life" is the invocation name of this hypothetical skill.
User: "What was the day on {1st May, 1996}" // {1st May, 1996} is the value received by slot
{Date}
Alexa: "It was a Wednesday".
Slots Type
The Alexa Skills Kit supports several slot types that define how data in the slot is recognized and handled. There are built-in slot (list of slot types), as well as the developer can specify their own custom slot. When creating their custom slots they are required to give some slot values, in the Alexa skill builder's build section. When the Alexa skill comes across such values, it would know these are the slot values of the custom build slot.
Since the skill can be published in several languages (see languages supported by Alexa), the build-in slots are also supported in several languages.
Defining slots
Slots may be defined in the Build section of new Alexa skill builder or using the JSON Editor to edit the Intent Schema.
This is how the slots Query and CityList are defined in the intent schema.
{
"intents": [
{
"name": "SearchIntent",
"slots": [
{
"name": "Query",
"type": "AMAZON.SearchQuery"
},
{
"name": "CityList",
"type": "AMAZON.US_CITY"
}
],
"samples": [
"search for {Query} near me",
"find out {Query}",
"search for {Query}",
"give me details about {CityList}"
]
}
]
}
Synonyms for slot values
The slot values defined in Alexa skill builder can have synonyms too. For example, if you're working with a skill which asks for the city in which the user lives, then places like Mumbai and Banglore could have synonyms Bombay and Bengaluru, respectively.
Slot Filling
For filling slots there are two cases which the developer must understand.
- Slot value is always required.
- Slot value is sometimes required, i.e. the skill will still work if this slot is missing.
If the slot value is always required, then the Directive Dialog.Delegate may be used. To use this directive, prompts (i.e. what Alexa will say to ask for the value of this slot) and utterances (i.e. what user will speak in response to those prompts) should be defined in the Alexa skill builder.
Like this :
Here the prompts and utterances are given for the custom slot CITY which is required by Intent GetMoviesNowShowing. (It is a built-in slot of type AMAZON.City)
And if the slot is not always required, then the Directive Dialog.ElicitSlot may be used. For this directive no prompts and utterances are required, the developer has to provide explicit outputSpeech, which is used by Alexa as a prompt for the slot filling.
Accessing slot values
The slot values may be accessed in the lambda function. When an intent is invoked, a JSON input is given to the lambda function. Developer can access this JSON input to retrieve the slot value input given by the user. It looks something like this:
"intent": {
"name": "GetAntonymsIntent",
"confirmationStatus": "NONE",
"slots": {
"LANGUAGE": {
"name": "LANGUAGE",
"confirmationStatus": "NONE",
"value" : "english"
},
"WORD": {
"name": "WORD",
"value": "ace",
"resolutions": {
"resolutionsPerAuthority": [
{
"authority": "amzn1.er-authority.echo-sdk.amzn1.ask.skill.c4a5d570-8455-4496-825b-07864b4acfec.WORD",
"status": {
"code": "ER_SUCCESS_MATCH"
},
"values": [
{
"value": {
"name": "ace",
"id": "360e2ece07507675dced80ba867d6dcd"
}
}
]
}
]
},
"confirmationStatus": "NONE"
}
}
}
This is just a concerned part of JSON input. This is not the complete input. The complete input / event looks something like this.
Here the slots LANGUAGE and WORD have values "english" and "ace", respectively.
There can be as many slots as the developer desire, but having a lot of them increases the complexity of the skill.
Questions related to any topic discussed above should have this tag, along with tags like Alexa and Alexa-skills-kit.
