Declarative UI Description

Overview

The Declarative UI Description is an optional feature that allows plugins to provide a declarative description of the UI components for their configuration. This feature enables the EMQX Dashboard to dynamically generate configuration forms, making it easier to configure and manage plugins.

Configuration Item Descriptions

• component
  Required. Specifies the component type for displaying and configuring data of different values and types. Supported components include:

  Component Name	Description
  input	Text input box for short texts or strings
  input-password	Password input box that conceals input
  input-number	Numeric input box allowing only numeric input
  input-textarea	Text area for longer text entries
  input-array	Array input box for comma-separated values, supporting string and numeric arrays
  switch	Toggle switch for boolean values
  select	Dropdown selection box for enumerated types
  code-editor	Code editor for specific formats (e.g., SQL, JSON)
  key-value-editor	Editor for editing key-value pairs in Avro maps
  maps-editor	Editor for editing object arrays in Avro objects

• label
  Required. Defines the field's label or name, supports $msgid for internationalization. If i18n is not configured, the original text will be displayed directly.

• description
  Optional. Provides a detailed description of the field, supports $msgid for internationalization. If i18n is not configured, the original text will be displayed directly.

• flex
  Required. Defines the proportion of the field in the grid layout; a full grid (24) spans an entire row, while a half grid (12) covers half a row.

• required
  Optional. Indicates whether the field is mandatory.

• format (Applicable only for code-editor component)
  Optional. Specifies the supported data formats, such as sql or json.

• options (Applicable only for select component)
  Optional. Lists the selectable options, aligned with the symbols in the Avro Schema. Example:

  [
    {
      "label": "$mysql",
      "value": "MySQL"
    },
    {
      "label": "$pgsql",
      "value": "postgreSQL"
    }
  ]
  

• items (Applicable only for maps-editor component)
  Optional. When using the maps-editor component, specify the field name and description of the items in the form. For example:

  {
    "items": {
      "optionName": {
        "label": "$optionNameLabel",
        "description": "$optionDesc",
        "type": "string"
      },
      "optionValue": {
        "label": "$optionValueLabel",
        "description": "$optionValueDesc",
        "type": "string"
      }
    }
  }
  

• rules
  Optional. Defines validation rules for the field, where multiple rules can be configured. Supported types include:

  • pattern: Requires a regular expression for validation.
  • range: Validates numeric input within a specified range. This validation can be configured with both a minimum value (min) and a maximum value (max), which can be set either together or independently.
  • length: Validates the character count of input, ensuring it falls within a specified range. This validation rule allows for the configuration of both a minimum length (minLength) and a maximum length (maxLength), which can be set either together or individually.
  • message: Specifies an error message to display when validation fails. This supports internationalization using $msgid to accommodate multiple languages.

Example Validation Rules

The following are several example snippets. For more detailed examples, refer to priv/config_schema.avsc.example:

{
    "rules": [
    {
      "type": "pattern",
      "pattern": "^([a-zA-Z0-9]|[a-zA-Z0-9][a-zA-Z0-9\\-]{0,61}[a-zA-Z0-9])(\\.([a-zA-Z0-9]|[a-zA-Z0-9][a-zA-Z0-9\\-]{0,61}[a-zA-Z0-9]))*$",
      "message": "$hostname_validate"
    }
  ]
}

{
    "rules": [
    {
      "type": "range",
      "min": 1,
      "max": 65535,
      "message": "$port_range_validate"
    }
  ]
}

{
    "rules": [
    {
      "type": "length",
      "minLength": 8,
      "maxLength": 128,
      "message": "$password_length_validate"
    },
    {
      "type": "pattern",
      "pattern": "^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)[a-zA-Z\d]*$",
      "message": "$password_validate"
    }
  ]
}

Localization

There is also an optional internationalization (i18n) config file, located at priv/config_i18n.json. This file is structured as key-value pairs, for example: { "$msgid": { "zh": "消息", "en": "Message" } }. To support multiple languages in field names, descriptions, validation rule messages, and other UI elements in the $ui configuration, use $msgid prefixed with $ in the relevant UI configurations.