Support variables in written/coded workflows

[jwillmer]

Real world problem:

As a developer I write the following example(!) workflow for a customer (not via UI):

The customer likes to query the last 10 sold items in his store and lookup his purchase price for the items in a document. Then he likes to know how much he have earned.

I implemented it and all are happy.

...

• After 2 weeks the customer asks me if I can change the query to lookup the last 30 items he sold.
• A week later he would like to revert his decision and only get the last 10 items.
• Two months ahead and he has changed the name of the document with all the purchase prices and likes me to update the workflow.
• And so on

Proposed solution

As a developer I would like to define properties in my workflow that the user can set via the UI. I would then implement the example workflow like this:

The customer likes to query the last {{ ItemCount = 10 }} sold items in his store and lookup his purchase price for the items in a {{ DocumentName = "purchase_prices.xml" }}. Then he likes to know how much he have earned.

This way my customer can make simple changes by his own without my intervention. There should be an option menu in the workflow UI there the customer sees all available properties and there he can change the values of it.

[jwillmer]

This could be done quiet simple with the env variables:

• Add a new section called env variables to the start btn of a workflow with a env list like in VisualStudio

• If I create a workflow in the UI I can create new env variables / If the workflow was coded I see a list of defined variables and only can change the value

• The env variables are actually used as env variables and will be set before the workflow starts

• All activities have access to the variables and they are read only

In the code it could be queried like this: var count = int.Parse(Environment.GetEnvironmentVariable("ItemCount") ?? "10", 10)

and set like this: Environment.SetEnvironmentVariable("ItemCount", 10, "Description of the env variable")

[sfmskywalker]

@Axeleron007 implemented the foundation upon which this feature can be implemented further.

The Elsa.WorkflowSettings project implements the necessary models and services that allows us to associate user-defined settings with workflow blueprints.

Currently, this feature is used to allow the user to disable workflow blueprints by setting the "disabled" setting (which can be regarded as a system-level setting).

What we need to do to implement this task is as follows:

• [ ] Add a new tab to the Workflow Definition Editor screen called Properties.
• [ ] From this tab, the user should be able to add new setting entries (as per @jwillmer 's wireframe) with default values. NOTE: These settings will be part of the Workflow Definition model, NOT created as WorkflowSetting records. They basically act as a blueprint for configurable settings.
• [x] For activities to be able to reference these settings, we need to extend the JavaScript and Liquid vocabulary. E.g. for JS: settings.MySetting.
• [x] Liquid: {{ Settings.MySetting }}.
• [ ] We also need to extend the Workflow Builder API to allow the developer to define settable settings with default values.
• [ ] The user should be able to provide custom values from the Workflow Blueprint Viewer screen. Workflow blueprints are derived from both designed workflows as well as C# workflows. This is the main reason we let the user provide customized workflow setting values from this screen (we can't let the user change C# source code to customize workflow settings). To provide custom values for the predefined settings, the Workflow Blueprint Viewer's panel should also get a new tab called Settings. This will look similar to the Settings tab in the Workflow Definition Editor, but here the user will not be able to define new settings; instead, they can override the values for the predefined settings. When saving the settings, the system will have to upsert WorkflowSetting records (using the already implemented workflow-settings API endpoint in the Elsa.WorkflowSettings.Api project.