Explanation of the usage of dynamic catalogs provided by the Web-API Gateway as editable pick-up lists in metadata forms.

Introduction

In some metadata fields, you may want to provide a selection list of possible values from which the users have to choose. Those lists are configured via so-called catalogs. By setting or not setting the property readonly in their schema definition, they can be configured to be editable directly in your client  for users with the proper authorization. A change in the schema definition is not required in order to modify the so-called dynamic catalogs.

Dynamic catalogs are introduced with version 2021 Summer at the latest. Beginning with 2021 Summer Alpha2, the Web-API Gateway offers the endpoints for maintaining such catalogs.

Notes:

• We use the term catalog from a technical perspective and the term list from the user's perspective.
• The catalog elements can't be localized.
• The elements of a list can't be manipulated by client form scripting.

Dynamic Catalogs used by one specific Tenant

If only one specific tenant will use a dynamic catalog, it is recommended to configure this catalog with the attibute classification for the field that should contain one of its values. In the following code block, an example schema definition of the example string property contract is displayed. The property is classified by line 6 to be a a dynamic catalog that is displayed as a pick-list with the technical name contracts in your client. Initially, the list of values offered to users will be empty.

	<propertyStringDefinition>
		<id>contract</id>
		<propertyType>string</propertyType>
		<cardinality>single</cardinality>
		<required>false</required>
        <classification>dynamic:catalog[tenMytenant:contracts]</classification>
	</propertyStringDefinition>

If the example schema is uploaded as a tenant schema via the endpoint POST /api/admin/schema by a user of the example tenant Mytenant, the property contract will be available only in the specific tenant Mytenant. After restarting your client, the users will get an empty pick-list for the field called tenMytenant:contracts.

Set a Catalog to read-only

If a catalog should be stable after setting it up, the parameter readonly can be set into the classification attribute, e.g.:

<classification>dynamic:catalog[tenMytenant:contracts,readonly]</classification>

Thus, the pick-list will not be editable in the client or via the admin-contoller of the Web-API gateway.

Editing via Client

Users with the role YUUVIS_MANAGE_SETTINGS can maintain this list. The following actions are supported:

• Create a new list element.
• Remove a list element. A warning is given if this element is used by an object.
• Disable a list element. Such elements are offered for search but not during creating or editing an object.

The edit dialog can be opened by clicking the pencil symbol at the field. The screenshot below shows the edit dialog for the example pick-list contracts where the four values Employment contract, Rental agreement, User contract and Purchase contract were already added.

The client uses the Web-API Gateway dms-controller endpoints: 

• The list elements from the catalog are read with the GET endpoint https://<domain>/api-web/dms/catalogs/tenMytenant:contracts.
  
• If the catalog does not exist it is created with the POST endpoint https://<domain>/api-web/dms/catalogs/tenMytenant:contracts.
• If the catalog does exist changes of its list elements are saved with the PATCH endpoint https://<domain>/api-web/dms/catalogs/tenMytenant:contracts.

Editing via admin-controller of Web-API Gateway

Users with the role YUUVIS_TENANT_ADMIN are offered the same maintenance actions via the Web-API Gateway GET, POST and PATCH endpoints: https://<domain>/api-web/admin/catalogs/tenMytenant:contracts of the admin-controller.

The catalog data is saved in the config server beside the tenant schema configuration.

The format of the catalogs is JSON. The following example shows a list of four elements stored for the tenant Mytenant:

{
  "tenant": "Mytenant",
  "entries": [
    {
      "name": "Employment contract",
      "disabled": false
    },
    {
      "name": "Rental agreement",
      "disabled": false
    },
    {
      "name": "User contract",
      "disabled": false
    },
    {
      "name": "Purchase contract",
      "disabled": false
    }
  ]
}

There is a Swagger-UI that supports you in using the mentioned endpoints: https://<domain>/api-web/swagger-ui.html. The screenshot below displays a part of the Web-API Gateway Swagger-UI showing the first endpoints of the admin-controller.

Global Dynamic Catalogs used by all Tenants

Read-only Global Catalogs

In this case, your tenants should use object types that are configured in a system or app schema and should use only standard values. Users with the role YUUVIS_SYSTEM_INTEGRATOR can set up global catalogs with initial standard elements and set the catalogs readonly. 

Recommendation: In an app schema, use the prefix of the application for your catalog name as given here:

	<propertyStringDefinition>
		<id>contract</id>
		<propertyType>string</propertyType>
		<cardinality>single</cardinality>
		<required>false</required>
        <classification>dynamic:catalog[appMyapplication:contracts,readonly]</classification>
	</propertyStringDefinition>

Recommendation: In the system schema, use no prefix for your catalog name as given here:

	<propertyStringDefinition>
		<id>contract</id>
		<propertyType>string</propertyType>
		<cardinality>single</cardinality>
		<required>false</required>
        <classification>dynamic:catalog[contracts,readonly]</classification>
	</propertyStringDefinition>

In this case the Web-API Gateway system-controller endpoints GET and POST are used.

• For the catalog contracts in the system schema: https://<domain>/api-web/system/catalogs/contracts
• For the catalog contracts in the app schema businesspartner: https://<domain>/api-web/system/catalogs/appMyapplication:contracts?appschemaname=appMyapplication

Global catalogs without an appschemaname are saved in the config-service beside the system schema configuration. Otherwise, the catalogs are saved besides the app schema configurations.

The Web-API Gateway GET endpoint that the client calls checks first whether a tenant-specific copy of the global catalog does exist. If not the global catalog is read.

Editable Global Catalogs

If the catalog parameter readonly is not set users with the role YUUVIS_MANAGE_SETTINGS can change the list elements. With the first update of such a catalog, a new catalog with the same technical name is saved for that tenant.

Note: From now on changes made in the global catalog are not affecting the copy. Only new tenants will get the new list elements of the global catalog.