Custom Url Picker

Overview

The picker that allows you to select a list of values retrieved from an external Microservice.

Configuration

The following configuration must be set in order to start using the CustomUrlPicker:

tags:
  title: Tags
  type: array
  description: a field implementing Custom URL picker
  ui:field: CustomUrlPicker
  ui:options:
    maxNumberToSelect: 3
    allowArbitraryValues: true
    selectedField: value
  ui:fieldsToSave:
    - id
    - value
    - description
  ui:displayFields:
    - value
  ui:apiSpec:
    retrieval:
      microserviceId: 'mocked-microservice-id'
      baseUrl: http://url.com // OPTIONAL
      path: /some/path // OPTIONAL
      method: POST // OPTIONAL
      params:
        limit: 5
        areaType: 'marketing'
    validation:
      microserviceId: 'mocked-microservice-id'
      baseUrl: http://url.com // OPTIONAL
      path: /some/path // OPTIONAL
      method: POST // OPTIONAL

The ui:options property can contain three possible values: maxNumberToSelect, allowArbitraryValues and selectedField. The first one is optional, this means that if not provided the Custom URL Picker enables users to select how many values they want, otherwise it limit the number of item that a user can select to the maxNumberToSelect number. The second one is optional and has a default value to false. If true, it enables users to type arbitrary strings inside the picker and press Enter to confirm the value. The third one is used to select the selected object's field to visualize inside the picker (as showed below).

warning

If allowArbitraryValues is true and the maxNumberToSelect is defined, the user can add as many values it wants until the maxNumberToSelect value is reached.

warning

If allowArbitraryValues is true, the Custom URL Picker will not perform any validation on the selected values.

The ui:fieldsToSave property is used to select the value's attributes that we want to save in the catalog-info.yaml file. It is an optional field and in case it is missing, the value's attributes to save are considered the ones under ui:displayFields (see the section below).

warning

The only mandatory field to insert under ui:fieldsToSave is the id otherwise the Custom URL Picker cannot render correctly the option selected and, also, it cannot perform correctly the validation.

The ui:displayFields property is used to select the returned object fields to visualize in the drop-down list of the picker (as showed below).

The ui:displayFields property must be a sub-set of the ui:fieldsToSave property. For example, if there are id, value and description under ui:fieldsToSave and name under ui:displayFields, the following error will be shown:

warning

The ui:options.selectedField property should also be included in the ui:displayFields property.

The ui:apiSpec property is an object that contains the API specifications to which the Picker will send the requests for the two phases of the Custom URL Picker: retrieval and validation. The first one is executed only when the creation wizard is opened, while the second one is executed when the edit wizard is opened or before deploying a data product descriptor in order to see if the picker contains the right data. The object for retrieval and validation is composed by the following fields:

• microserviceId: an identifier that will be used to take the API key that will be set in the Witboost configuration file
• baseUrl: an optional field defining the URL used to perform an HTTP call
• path: an optional field defining the path used to perform the HTTP request
• method: an optional field defining the method used to perform the HTTP request
• params: an optional object that will be put in the body of the request. It can contain static fields like the one showed in the above example or dynamic fields (see the Dynamic Field section). The params field can contain also the limit parameter that defines the number of values that the Custom URL Picker will receive for each request to the Microservice. It is an optional field and the default (and minimum) value is 5. This parameter will also be passed to the body of the validation API as queryParameters property. This is because the validation API needs the same body of the retrieval in order to perform its operation.

warning

The baseUrl, path and method parameters are optional, i.e. when a user defines them, they will overwrites the one that are inside the Witboost configurations.

warning

The params parameter should contain also the "limit" that cannot be less than 5. In case you do not put anything in there, the limit will have default value 5.

warning

Do not put a value less than 5 for limit parameter.

Infinite scrolling mechanism

The CustomURLPicker incorporates a feature that enables pagination of microservice results through an infinite scrolling mechanism. This mechanism utilizes a query parameter named "offset," which represents a numeric value. For instance, suppose a user is browsing a list of items retrieved from the microservice. As they reach the end of the current list, the "offset" parameter is incremented by one.

Let's consider an example:

Initially, the user loads the page and the offset parameter is set to 0. The microservice returns the first batch of items, say 10 elements (set by the limit value), based on this offset value. As the user scrolls down and reaches the end of the drop-down list, the offset parameter is incremented to 1. Subsequently, the microservice retrieves the next 10 elements starting from the index specified by the updated offset value (in this case, 10).

This process continues as the user scrolls further, with the offset parameter incrementing by one each time and the microservice fetching the subsequent batch of items accordingly. The Custom URL Picker seamlessly appends these newly retrieved elements to the existing ones, providing a continuous and uninterrupted browsing experience for the user.

tip

The Custom URL Picker does not know anything regarding how many values the external microservice will return. It will just increase the offset number and append the microservice results to the existing ones. The microservice will compute the values to return to the Custom URL Picker by considering the offset mechanism described above.

Dynamic fields

The Custom Url Picker enables users to put under ui:apiSpec.retrieval.params property, some fields that have some special value chars: ${{ fieldName }}. This means that a user can put the value for that field to the one that is inside the "fieldName" field in the same template. For example, the following template.yaml file contains two fields email and tags. The user has defined an emailValue property under params with the special characters described above. The Custom URL Picker will take the value that the builder user will put in the email field of the template and put that value in the emailValue field.

email:
  title: Contact email
  type: string
  format: email
  description: Point of contact, it could be the owner or a distribution list, but must be reliable and responsive
tags:
  title: Tags
  type: array
  description: a field implementing Custom URL picker
  ui:field: CustomUrlPicker
  ui:options:
    allowArbitraryValues: true
    selectedField: name
  ui:displayFields:
    - id
    - name
  ui:apiSpec:
    retrieval:
      microserviceId: 'mocked-microservice-id'
      params:
        limit: 5
        areaType: 'marketing'
        emailValue: ${{ email }}
    validation:
      microserviceId: 'mocked-microservice-id'

The user can use dynamic fields in multiple ways:

• In a nested object property:

params:
  limit: 5
  areaType: 'marketing'
  emailValue:
    name: ${{ email }}
    domain: agilelab.it

• In an array:

params:
  limit: 5
  areaType: 'marketing'
  emailValue: ['${{ email }}', 'name.surname@company.it']

• In both of them:

params:
  limit: 5
  areaType: 'marketing'
  emailValue:
    values: ['${{ email }}', name.surname@company.it]
    domain: agilelab.it

warning

It is possibile to put in the special characters only the field names that are in the same step of the Custom URL picker.

warning

When a dependent field changes, the custom URL picker will be reset.

warning

If the dynamic field cannot be resolved, a warning will be displayed: The dynamic field "${fieldName}" is empty or wrong. It will be skipped from the request body.. So make sure to reference the correct field name.

warning

Avoid to put another Custom URL Picker which depends from yours as dynamic field (cyclic dependency) in order to avoid unexpected results.

warning

Avoid to put the Custom URL Picker itself as a dynamic field in order to avoid unexpected results.

Witboost configuration

In order to use the Custom URL Picker we need to define some configuration properties inside Witboost app-config.yaml file under mesh.builder.scaffolder section.

mesh:
  builder:
    scaffolder:
      microserviceConfiguration:
        - microserviceId: microservice-id
          baseUrl: https://someuri.com
          retrievalPath: /some/retrieval/path // OPTIONAL
          validationPath: /some/validation/path // OPTIONAL
          retrievalMethod: POST // OPTIONAL
          validationMethod: POST // OPTIONAL
          apiKey: api_key_value // OPTIONAL

The fields microserviceId and baseUrl are mandatory while apiKey, retrievalPath, validationPath, retrievalMethod, validationMethod are optional and can be put in there only the Microservice wants to expose API with different paths and methods. For what concern the apiKey configuration, this will be set only if the Microservice requires some authenticated requests (in this case the value of apiKey will be set in the header parameter X-API-Key).

warning

The baseUrl, retrievalPath, validationPath, retrievalMethod, validationMethod fields can be overwritten by putting the same parameters in the template.yaml file, under ui:apiSpec.retrieval or ui:apiSpec.validation.

warning

The retrievalPath and validationPath configurations must start with '/' to avoid unexpected behaviours.

Microservice APIs

In order to make the microservice compatible with the Custom URL Picker specifications, it must implement two APIs: POST v1/resources and POST v1/resources/validate. These APIs must be compliant to the corresponding Open API specification.

tip

The API paths (v1/resources and v1/resources/validate) can be changed as you want. If you do that, remember to change their references under mesh.builder.scaffodler.microserviceConfiguration.retrievalPath and mesh.builder.scaffolder.microserviceConfiguration.validationPath if you are defining the API in the configuration, or under ui:apiSpec.retrieval.path and ui:apiSpec.validation.path if you are defining the API in the templates.