Actor input schema specification

Learn how to define and validate a schema for your Actor's input with code examples. Provide an autogenerated input UI for your Actor's users.

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The input schema serves two primary purposes for an Actor:

• It defines the structure and validation rules for the input data the Actor accepts.
• It determines the user interface components rendered in the Apify Console for configuring the Actor's input.

By defining an input schema, you can provide a user-friendly interface for configuring your Actor while ensuring that the input data supplied by users adheres to the specified requirements and constraints.

You can specify input schema for an Actor in multiple ways:

• One approach embeds it as an object within the .actor/actor.json file under the input field or provide a path to a JSON file containing the input schema in the same input field.
• If you omit the input field in the .actor/actor.json file, the system will look for an INPUT_SCHEMA.json file in the .actor directory.
• In the absence of that file, it will search for an INPUT_SCHEMA.json file in the Actor's root directory.

The max allowed size for the input schema file is 500 kB. When you provide an input schema, the system will validate the input data passed to the Actor during execution (via the API or the Apify Console) against the specified schema to ensure compliance before starting the Actor.

Validation aid

You can also use our visual input schema editor to guide you through the creation of the INPUT_SCHEMA.json file. If you need to validate your input schemas, you can use the apify validate-schema command in the Apify CLI.

Example

Imagine a simple web crawler that accepts an array of start URLs and a JavaScript function to execute on each visited page. The input schema for such a crawler could be defined as follows:

{
    "title": "Cheerio Crawler input",
    "description": "To update crawler to another site, you need to change startUrls and pageFunction options!",
    "type": "object",
    "schemaVersion": 1,
    "properties": {
        "startUrls": {
            "title": "Start URLs",
            "type": "array",
            "description": "URLs to start with",
            "prefill": [
                { "url": "http://example.com" },
                { "url": "http://example.com/some-path" }
            ],
            "editor": "requestListSources"
        },
        "pageFunction": {
            "title": "Page function",
            "type": "string",
            "description": "Function executed for each request",
            "prefill": "async () => { return $('title').text(); }",
            "editor": "javascript"
        }
    },
    "required": ["startUrls", "pageFunction"]
}

The generated input UI will be:

If you switch the input to the JSON display using the toggle, then you will see the entered input stringified to JSON, as it will be passed to the Actor:

{
    "startUrls": [
    {
        "url": "http://example.com"
    },
    {
        "url": "http://example.com/some-path"
    }
    ],
    "pageFunction": "async () => { return $('title').text(); }"
}

Structure

{
    "title": "Cheerio Crawler input",
    "type": "object",
    "schemaVersion": 1,
    "properties": { /* define input fields here */ },
    "required": []
}

Property	Type	Required	Description
title	String	Yes	Any text describing your input schema.
description	String	No	Help text for the input that will be displayed above the UI fields.
type	String	Yes	This is fixed and must be set to string object.
schemaVersion	Integer	Yes	The version of the input schema specification against which your schema is written. Currently, only version 1 is out.
properties	Object	Yes	This is an object mapping each field key to its specification.
required	String	No	An array of field keys that are required.

Input schema differences

Even though the structure of the Actor input schema is similar to JSON schema, there are some differences. We cannot guarantee that JSON schema tooling will work on input schema documents. For a more precise technical understanding of the matter, feel free to browse the code of the @apify/input_schema package.

Fields

Each field of your input is described under its key in the inputSchema.properties object. The field might have integer, string, array, object, or boolean type, and its specification contains the following properties:

Property	Value	Required	Description
type	One of string array object boolean integer	Yes	Allowed type for the input value. Cannot be mixed.
title	String	Yes	Title of the field in UI.
description	String	Yes	Description of the field that will be displayed as help text in Actor input UI.
default	Must match type property.	No	Default value that will be used when no value is provided.
prefill	Must match type property.	No	Value that will be prefilled in the Actor input interface. Only the boolean type doesn't support prefill property.
example	Must match type property.	No	Sample value of this field for the Actor to be displayed when Actor is published in Apify Store.
sectionCaption	String	No	If this property is set, then all fields following this field (this field included) will be separated into a collapsible section with the value set as its caption. The section ends at the last field or the next field which has the sectionCaption property set.
sectionDescription	String	No	If the sectionCaption property is set, then you can use this property to provide additional description to the section. The description will be visible right under the caption when the section is open.

Prefill vs. default vs. required

Here is a rule of thumb for whether an input field should have a prefill, default, or be required:

• Prefill - Use for fields that don't have a reasonable default. The provided value is prefilled for the user to show them an example of using the field and to make it easy to test the Actor (e.g., search keyword, start URLs). In other words, this field is only used in the user interface but does not affect the Actor functionality and API.
• Required - Use for fields that don't have a reasonable default and MUST be entered by the user (e.g., API token, password).
• Default - Use for fields that MUST be set for the Actor run to some value, but where you don't need the user to change the default behavior (e.g., max pages to crawl, proxy settings). If the user omits the value when starting the Actor via any means (API, CLI, scheduler, or user interface), the platform automatically passes the Actor this default value.
• No particular setting - Use for purely optional fields where it makes no sense to prefill any value (e.g., flags like debug mode or download files).

In summary, you can use each option independently or use a combination of Prefill + Required, but the combinations Prefill + Default or Default + Required don't make sense to use.

Additional properties

Most types also support additional properties defining, for example, the UI input editor.

String

Example of a code input:

{
    "title": "Page function",
    "type": "string",
    "description": "Function executed for each request",
    "editor": "javascript",
    "prefill": "async () => { return $('title').text(); }"
}

Rendered input:

Example of country selection using a select input:

{
    "title": "Country",
    "type": "string",
    "description": "Select your country",
    "editor": "select",
    "default": "us",
    "enum": ["us", "de", "fr"],
    "enumTitles": ["USA", "Germany", "France"]
}

Rendered input:

Properties:

Property	Value	Required	Description
editor	One of textfield textarea javascript python select datepicker hidden	Yes	Visual editor used for the input field.
pattern	String	No	Regular expression that will be used to validate the input. If validation fails, the Actor will not run.
minLength	Integer	No	Minimum length of the string.
maxLength	Integer	No	Maximum length of the string.
enum	[String]	Required if editor is select	Using this field, you can limit values to the given array of strings. Input will be displayed as select box.
enumTitles	[String]	No	Titles for the enum keys described.
nullable	Boolean	No	Specifies whether null is an allowed value.
isSecret	Boolean	No	Specifies whether the input field will be stored encrypted. Only available with textfield and textarea editors.

Regex escape

When using escape characters \ for the regular expression in the pattern field, be sure to escape them to avoid invalid JSON issues. For example, the regular expression https:\/\/(www\.)?apify\.com\/.+ would become https:\\/\\/(www\\.)?apify\\.com\\/.+.

Boolean

Example options with group caption:

{
    "verboseLog": {
        "title": "Verbose log",
        "type": "boolean",
        "description": "Debug messages will be included in the log.",
        "default": true,
        "groupCaption": "Options",
        "groupDescription": "Various options for this Actor"
    },
    "lightspeed": {
        "title": "Lightspeed",
        "type": "boolean",
        "description": "If checked then actors runs at the
            speed of light.",
        "prefill": true
    }
}

Rendered input:

Properties:

Property	Value	Required	Description
editor	One of checkbox hidden	No	Visual editor used for the input field.
groupCaption	String	No	If you want to group multiple checkboxes together, add this option to the first of the group.
groupDescription	String	No	Description displayed as help text displayed of group title.
nullable	Boolean	No	Specifies whether null is an allowed value.

Integer

Example:

{
    "title": "Memory",
    "type": "integer",
    "description": "Select memory in megabytes",
    "default": 64,
    "maximum": 1024,
    "unit": "MB"
}

Rendered input:

Properties:

Property	Value	Required	Description
editor	One of: number hidden	No	Visual editor used for input field.
maximum	Integer	No	Maximum allowed value.
minimum	Integer	No	Minimum allowed value.
unit	String	No	Unit displayed next to the field in UI, for example second, MB, etc.
nullable	Boolean	No	Specifies whether null is an allowed value.

Object

Example of proxy configuration:

{
    "title": "Proxy configuration",
    "type": "object",
    "description": "Select proxies to be used by your crawler.",
    "prefill": { "useApifyProxy": true },
    "editor": "proxy"
}

Rendered input:

The object where the proxy configuration is stored has the following structure:

{
    // Indicates whether Apify Proxy was selected.
    "useApifyProxy": Boolean,

    // Array of Apify Proxy groups. Is missing or null if
    // Apify Proxy's automatic mode was selected
    // or if proxies are not used.
    "apifyProxyGroups": String[],

    // Array of custom proxy URLs.
    // Is missing or null if custom proxies were not used.
    "proxyUrls": String[],
}

Example of a blackbox object:

{
    "title": "User object",
    "type": "object",
    "description": "Enter object representing user",
    "prefill": {
        "name": "John Doe",
        "email": "janedoe@gmail.com"
    },
    "editor": "json"
}

Rendered input:

Properties:

Property	Value	Required	Description
editor	One of json proxy hidden	Yes	UI editor used for input.
patternKey	String	No	Regular expression that will be used to validate the keys of the object.
patternValue	String	No	Regular expression that will be used to validate the values of object.
maxProperties	Integer	No	Maximum number of properties the object can have.
minProperties	Integer	No	Minimum number of properties the object can have.
nullable	Boolean	No	Specifies whether null is an allowed value.

Array

Example of request list sources configuration:

{
    "title": "Start URLs",
    "type": "array",
    "description": "URLs to start with",
    "prefill": [{ "url": "https://apify.com" }],
    "editor": "requestListSources"
}

Rendered input:

Example of an array:

{
    "title": "Colors",
    "type": "array",
    "description": "Enter colors you know",
    "prefill": ["Red", "White"],
    "editor": "json"
}

Rendered input:

Properties:

Property	Value	Required	Description
editor	One of json requestListSources pseudoUrls globs keyValue stringList select hidden	Yes	UI editor used for input.
placeholderKey	String	No	Placeholder displayed for key field when no value is specified. Works only with keyValue editor.
placeholderValue	String	No	Placeholder displayed in value field when no value is provided. Works only with keyValue and stringList editors.
patternKey	String	No	Regular expression that will be used to validate the keys of items in the array. Works only with keyValue editor.
patternValue	String	No	Regular expression that will be used to validate the values of items in the array. Works only with keyValue and stringList editors.
maxItems	Integer	No	Maximum number of items the array can contain.
minItems	Integer	No	Minimum number of items the array can contain.
uniqueItems	Boolean	No	Specifies whether the array should contain only unique values.
nullable	Boolean	No	Specifies whether null is an allowed value.
items	object	No	Specifies format of the items of the array, useful mainly for multiselect (see below)

Usage of this field is based on the selected editor:

• requestListSources - value from this field can be used as input for the RequestList class from Crawlee.
• pseudoUrls - is intended to be used with a combination of the PseudoUrl class and the enqueueLinks() function from Crawlee.

Editor type requestListSources supports input in formats defined by the sources property of RequestListOptions.

Editor type globs maps to the Crawlee's GlobInput used by the UrlPatterObject.

Editor type select allows the user to pick items from a select, providing multiple choices. Please check this example of how to define the multiselect field:

{
    "title": "Multiselect field",
    "description": "My multiselect field",
    "type": "array",
    "editor": "select",
    "items": {
        "type": "string",
        "enum": ["value1", "value2", "value3"],
        "enumTitles": ["Label of value1", "Label of value2", "Label of value3"]
    }
}

To correctly define options for multiselect, you need to define the items property and then provide values and (optionally) labels in enum and enumTitles properties.

Resource type

Resource type identifies what kind of Apify Platform object is referred to in the input field. For example, the Key-value store resource type can be referred to using a string ID. Currently, it supports storage resources only, allowing the reference of a Dataset, Key-Value Store or Request Queue.

For Actor developers, the resource input value is a string representing the storage ID. The type of the property is either string or array. In case of array (for multiple resources) the return value is an array of IDs. In the user interface, a picker is provided for easy selection, where users can search and choose from their own storages or those they have access to.

Example of a Dataset input:

{
    "title": "Dataset",
    "type": "string",
    "description": "Select a dataset",
    "resourceType": "dataset"
}

Rendered input:

The returned value is resource reference, in this example it's the dataset ID as can be seen in the JSON tab:

Example of multiple datasets input:

{
    "title": "Datasets",
    "type": "array",
    "description": "Select multiple datasets",
    "resourceType": "dataset"
}

Rendered input:

Properties:

Property	Value	Required	Description
type	One of string array	Yes	Specifies the type of input - string for single value or array for multiple values
editor	One of resourcePicker hidden	No	Visual editor used for the input field. Defaults to resourcePicker.
resourceType	One of dataset keyValueStore requestQueue	Yes	Type of Apify Platform resource
minItems	Integer	No	Minimum number of items the array can contain. Only for type: array
maxItems	Integer	No	Maximum number of items the array can contain. Only for type: array