Actor input schema specification

Learn how to define and easily 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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An Actor's input schema defines the input that the Actor accepts and the UI components used for input in Apify Console. Using input schema, you can provide an easy-to-use UI for your Actor's users and also ensure that the input provided is valid.

Input schema can be embedded as an object in the .actor/actor.json file under the input field. Alternatively, you can store a path to a JSON file in that field. If the input field or .actor/actor.json are omitted, the input schema from .actor/INPUT_SCHEMA.json is used. In the absence of that file, the INPUT_SCHEMA.json file stored in the Actor's root directory is used. The file's maximum size is 100 kB. If the input schema is provided, then input is always validated to fulfill the schema when an Actor is being started (via API or from Apify Console).

You can also use our visual input schema editor to guide you through creation of the INPUT_SCHEMA.json file.

If you need to validate your input schemas, you can use the apify vis command in the Apify CLI.

Example

Imagine you are building a simple crawler whose inputs are an array of start URLs and a JavaScript function that will be executed at each page the crawler visits. Its input schema will look like this:

{
    "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"]
}

And generated the 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

The input schema is a JSON file named INPUT_SCHEMA.json, placed in the root directory of an Actor with the following 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.

Even though the structure of the Actor input schema is similar to JSON schema, there are a few important differences. Therefore, we cannot guarantee that JSON schema tooling will work correctly on input schema documents. For 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 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 separately or use a combination of Prefill + Required, but the combinations Prefill + Default or Default + Required don't make sense to use.

Additional properties

In addition to the properties listed above, most of the types support also 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.

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

Beware that the boolean input type doesn't support the prefill property, since there is no way to display the pre-filled value in the user interface.

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.",
        "default": 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": "http://example.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 of 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.