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App and UI Extension parameters

WARNING: Parameters can be read by anybody who belongs to a space where your app or UI extension is installed. It's not secure to use parameters to inject access tokens with access level permitting data manipulation. Read-only tokens can be used but keep in mind their value is not hidden.

Understanding parameters

It's important to achieve separation of the code that forms your custom App or UI extension and the configuration that is used by it. This way it can be shared, reused and reconfigured without any code changes. Good examples are:

  • default values
  • project, category or entity identifiers when loading data from external APIs
  • Slack channel name to post messages to
  • content types to process (e.g. for publishing content trees)
  • kinds of validation to apply
  • and many more...

There are two types of configuration parameters that can be set up:

  • Installation parameters that are set during installation in a space environment and which can be modified in subsequent configuration updates. Their values are available across all usages of the app or UI extension in the space environment.
  • Instance parameters that are set when a space member with access to the Content Model assigns an app or UI extension to a location. Values provided are available only in the specific location and content type where they were entered.

Parameter definition

Parameter definition is an object constructed as described in the table below.

Property Type and value Is required? Remarks
id String yes Can contain only letters, numbers and underscores
name String yes Human readable name of the parameter
description String no Further explanation of the purpose of the parameter
type String, one of Symbol, Enum, Number, Boolean yes Enum parameters hold a predefined list of Symbols
required Boolean no, defaults to false Whether the parameter value needs to be provided
default Should match type no Default value to use for the parameter. For Enums it has to be defined on the options list
options
  • list of allowed values: ["one", "two"]
  • can be a list of {"value": "Label"} pairs to provide labels for values
yes
  • applicable only to Enums
  • ["x", "y"] is equivalent to [{"x": "x"}, {"y": "y"}]
labels
  • for Enums: {"empty": "Choose a value"}
  • for Booleans: {"true": "sí", "false": "no"}
no Used for rendering a form. All labels are optional and have sensible defaults in English

Parameter definition for Apps

For Apps, installation parameters are a free-form object, with a limit of 16kB, and don't have to be defined.

Up to 8 instance paramters can be defined as a part the AppDefinition entity:

{
    "name": "My parametrized editor app",
    "src": "https://myeditor.contentful.com",
    "locations": [{"location": "entry-editor"}],
    "parameters": {
      "instance": [
        {
          "id": "helpText",
          "type": "Symbol",
          "name": "Help text",
          "description": "Help text for a user to help them understand the editor"
        },
        {
          "id": "theme",
          "type": "Enum",
          "name": "Theme",
          "options": [{"light": "Solarized light"}, {"dark": "Solarized dark"}],
          "default": "light",
          "required": true
        }
      ]
    }
}

You can define instance parameters for your app when editing the AppDefinition in the Web App:

instance parameters UI

Parameter definition for UI Extensions

Up to 8 instance and 8 installation parameters can be defined as a part of the Extension entity:

{
  "extension": {
    "name": "My parametrized object editor",
    "fieldTypes": [{type: "Object"}],
    "srcdoc": "<!DOCTYPE html>...",
    "parameters": {
      "installation": [
        {
          "id": "devMode",
          "type": "Boolean",
          "name": "Run in development mode"
        },
        {
          "id": "retries",
          "type": "Number",
          "name": "Number of retries for API calls",
          "required": true,
          "default": 3
        }
      ],
      "instance": [
        {
          "id": "helpText",
          "type": "Symbol",
          "name": "Help text",
          "description": "Help text for a user to help them understand the editor"
        },
        {
          "id": "theme",
          "type": "Enum",
          "name": "Theme",
          "options": [{"light": "Solarized light"}, {"dark": "Solarized dark"}],
          "default": "light",
          "required": true
        }
      ]
    }
  }
}

Setting and reading parameter values

Instance parameters are set in the Editor Interface entity. Installation parameters are provided as a top-level parameters property of the AppInstallation or Extension entities:

{
  "parameters": {
    "devMode": true,
    "retries": 10
  }
}

Values, for both instance and installation parameters, can be read with the SDK:

init(sdk => {
  console.log(sdk.parameters.instance)
  console.log(sdk.parameters.installation)
})

Note that both instance and installation are guaranteed to be an empty object if values were not provided.