JSON Schema for Schema Plugins

You define the schema plugin fields that appear in extendedFields with a subset of JSON schema. The plugin schema has some restrictions and additions set by Wix, but the general syntax, supported types, and keywords are mostly the same as JSON schema. Wix supports JSON schema version 2019-09 or higher.

General restrictions

As with a normal JSON schema, to define your plugin fields, you’ll add them as property keys to the properties object. Keep in mind the following restrictions on the schema:

• Plugin schemas can't contain more than 256 properties.

• The maximum length of a property key is 64 characters.

• Property keys must start with a letter and can contain only letters, numbers, and underscores.

• A schema plugin can store a maximum of 10 KB of data per object. This means that each site that installs your app can store up to 10 KB of data for each object that your app extends.

  For example, if your app extends both the booking and checkout objects, it has a total of 20 KB of database storage. It can use up to 10 KB for the Booking object schema, and up to 10 KB for the Checkout object schema.

  A schema’s maximum size is calculated based on the field types defined in the schema, including the maximum lengths of all strings and the maximum items of all arrays.

Schema properties

Root-level properties

The properties object

Supported types

The schema plugin supports all the basic JSON schema types, with some restrictions. These restrictions (if any) are detailed below for each type.

string

Size: Varies. Each character is 1 byte.

Restrictions:

• Length: Strings must be between 1 and 10,000 characters long.
• The maximum length of a string field must be defined using the maxLength keyword.

Supported formats:

The JSON schema supports the following format values:

• color-hex

• currency

• date-time

• date

• guid

• hostname

• language

• time

• uri

• email: A custom Wix value indicating a valid email address. The maximum length of an email address is 254 characters.

• phone: A custom Wix value indicating a valid phone number.

• single-line: The value single-line indicates a field that can only contain a single line of text. The string must end with a newline character (\n).

  Note: By default, a string field is considered multi-line text. If it is defined as single-line, the format can be removed later. However, if a string is created as multi-line text, the format can't be changed later to single-line, because this is a breaking change.

number

Size: 8 bytes

Restrictions:

• Minimum value: -2⁵³ + 1.
• Maximum value: 2⁵³ + 1.

integer

Size: 4 bytes

Restrictions:

• Minimum value: -2⁵³ + 1.
• Maximum value: 2⁵³ + 1.

object

Size: Varies

Restrictions:

• An object must contain a properties field that defines its properties.
• The object’s properties must follow the restrictions of the other types listed here.
• There is a maximum of 10 nesting levels for an object.

array

Size: An array’s size is determined by the type it contains and its max length. For example, given the following property:

1

The array contains a maximum of 20 integers. Therefore its total size is:

4 bytes/integer × 20 integers = 80 bytes.

Now consider an array of strings:

1

The array contains a maximum of 10 strings, each of which can have a maximum length of 10 characters. Since 1 character = 1 byte, we can calculate the array’s total size like this:

(10 characters × 1 byte/character) × 10 = 100 bytes.

Restrictions:

• An array must contain an items key that defines the type of items in the array.
• The items in the array must follow all the restrictions of the other types listed here.
• An array can contain a maximum of 100 items. The maximum number of items must be defined using the maxItems keyword.
• All the items in an array must be the same type.
• Arrays support items of type string, number, integer, boolean, and object.

boolean

Size: 1 byte

Restrictions: None

Supported keywords

The following global JSON schema keywords are supported:

• Annotations.
• Enumerated values.

The following global keywords are not supported:

• required
• $defs
• $ref
• readOnly
• writeOnly

Defining field permissions

For each field you add to the plugin schema, you need to define permissions. These permissions tell your app who can read and write to the field.

The permissions you define in the schema assume that the extended entity allows apps to read and write it. If an entity does not allow apps read and write permission, then no group will be able to read and write to the entity, no matter what permissions are defined.

There are four supported permission values:

• owning-app: The app that defines the extended field.
• apps: Other apps installed on the same site as the owning app.
• users: Collaborators of sites that have the owning app installed.
• users-of-users: Visitors of sites that have the owning app installed.

To add permissions to a field, include the Wix-specific x-wix-permissions keyword in the field object. In the value, include two arrays: one specifying the read permissions, and the second specifying the write permissions.

For example:

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When you create a schema plugin in the Dev center, owning-app read and write permissions are added by default. Therefore, you don’t need to explicitly define them in x-wix-permissions.

Editing the schema

Once you’ve saved the schema, there are limits on how you can edit it. You can only make non-breaking changes to the schema. Examples of non-breaking changes include:

• Adding a new field.
• Adding or removing permissions in an existing field.
• Increasing a field’s max limit (for example, the maxLength value in a string field).
• Decreasing a field’s min limit (for example, the value of minimum in a number or integer field).
• Removing a field’s min or max limit entirely.
• Changing settings like title, description and placeholder.

Examples of breaking changes are:

• Removing a field.
• Decreasing a field’s max limit.
• Increasing a field’s min limit.
• Adding a max or min limit to a field that didn’t have one before.

Archiving schema fields

You can’t delete fields from your schema, but you can archive them using the x-wix-archived keyword. As with permissions, add x-wix-archived to the field that you want to archive, and set it to true.

For example:

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The archived field remains in the database, so you cannot reuse its key for another field. During read operations, it is filtered out, and during write operations the field is ignored. A field that is archived still takes up the same amount of space in memory and therefore counts towards the 10 KB total your schema plugin can take up.

All the schema types support archiving. If the archived field has nested fields, the nested fields are also archived. To restore an archived extended field, change the value of x-wix-archived to false or remove it from the schema.

JSON validation errors

If your JSON schema doesn't align with the restrictions detailed above, you'll receive a validation error. Here are a few common errors and what they mean:

Example schema plugin

Here is an example of a schema plugin that defines firstName, lastName, and age fields. This is what the final schema looks like in the JSON Editor:

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