Declarative Based Flow (declarative-based-flow)

Declarative-Based Flow is a powerful and intuitive npm package designed to simplify the construction of complex, structured workflows using a declarative and fluent syntax. This package provides a seamless way to define, orchestrate, and execute a series of operations or commands with ease.

Key Features:

Fluent Syntax: Create workflows by chaining commands together in a declarative style, similar to popular query builders, making your code more readable and maintainable.

Command Abstraction: Define individual commands or operations as separate modules, allowing for better code organization and reusability.

Customizable Commands: Easily extend the package to include custom command classes that suit your specific needs, whether it's data transformation, external integrations, or business logic.

Simplified Workflow: Focus on the high-level logic of your application, while the package handles the orchestration and execution of commands.

Installation

You can install this package using npm or yarn:

npm install declarative-based-flow
# or
yarn add declarative-based-flow

USAGE

Flow

Flow is a specialized widget that represents the starting point of a workflow. It allows you to connect other widgets and execute the workflow. Here's how to create a Flow:

import { Flow } from 'declarative-based-flow';

const myFlow = Flow.create('my_flow').start(yourFirstWidget).end();

SetVariable

SetVariable is a widget used to set variables in a workflow. It allows you to define variables and specify their values using whitelabel expressions. Here's how to create a SetVariable widget:

import { SetVariable } from 'declarative-based-flow';

const mySetVariable = SetVariable.create('my_set_variable');
mySetVariable.variable('myVar', '{{ payload.data.value }}');

Compare

Compare is a utility class that provides comparison operations for use in conditional statements within the workflow. You can create a Comparator instance using the Compare class:

import { Compare } from 'declarative-based-flow';

const myComparator = Compare.is(42);
myComparator.equal(42); // true 

Split

Split is a widget that allows you to branch the workflow based on a specified condition. It provides a case method to define the condition and separate paths for different outcomes. Here's how to create a Split widget:

import { Split } from 'declarative-based-flow';

const mySplit = Split.create('my_split');
mySplit.case((data) => Compare.is(data.payload.value).equal('some_value'));
mySplit.moveTo(anotherWidget).elseMoveTo(aDiferentWidget);

Extending

You can easily create custom command classes (as widgets) with CustomWidget to suit your specific needs. Whether it's data transformation, external integrations, or business logic, Declarative-Based Flow allows you to abstract and encapsulate these operations. Here's an example using CustomWidget:

import { CustomWidget } from 'declarative-based-flow';

export class MyWidget extends CustomWidget {
    private myActions = {
        do: {
            something: undefined
        }
    }

    myCustomStep(someAction: any) {
        this.myActions.do.something = someAction

        return this;
    }

    async process(a: any): Promise<void> {
        if (!Reflect.has(this.myActions.do, 'something')) {
            throw new Error('Some error message!');
        }

        // TODO: Your business logic comes here!

        super.register(`Info you want to log!`, 'info'); // Use super.register to log data on your process.

        super.process(a);
    }
}

To use this customized Widget you should move as standard:

import { MyWidget } from './my-custom-widget'

const myCustomWidget = MyWidget.create('my_custom_widget').myCustomStep(() => console.log("Easy to customize!"));

// ... 

Flow.create('unamed').start(myCustomWidget).end()(myDataToProcess);

Examples

The package includes examples of how to use these widgets to build and execute workflows. You can refer to the provided test file for detailed usage examples:

• Creating and connecting widgets
• Defining variables with SetVariable
• Using Compare for conditional checks (mostly inside Split)
• Branching the workflow with Split

These examples should help you get started with building complex workflows using this package.

A fully running code should be like this:

    const amazingSetVariableWidgetOne = SetVariable
        .create('amazing_set_variable_widget_one')
        .variable('myVarOne', '{{ payload.act.like.that }}');

    amazingSetVariableWidgetOne.moveTo(
        Split
            .create('amazing_split_widget')
            .case((data: any) => Compare
                .is(data.payload.act.like.that)
                .in(['this', 'those', 'that'])
            )
            .moveTo(
                SetVariable
                    .create('amazing_set_variable_widget_three')
                    .variable('myVarThree', '{{ payload.act.like.those }}')
            )
            .elseMoveTo(
                SetVariable
                .create('amazing_set_variable_widget_two')
                .variable('myVarTwo', '{{ payload.act.like.this.should.be.this }}')
            )
        )
    
    const flow = Flow.create('amazing_flow').start(amazingSetVariableWidgetOne).end();

    const payload = flow({
        act: {
            like: { 
                that: 'that', 
                this: { 
                    should: { 
                        be: { 
                            this:'this' 
                        } 
                    } 
                }, 
                those: 'those' 
            }
        }
    });

Why Use Declarative-Based Flow

Declarative-Based Flow is ideal for projects that involve complex, multi-step processes, such as data transformations, ETL (Extract, Transform, Load), and workflow automation. By encapsulating each step within a chainable command structure, your code becomes more modular, flexible, and maintainable.

Simplify your application's control flow and enhance your codebase with Declarative-Based Flow.

License

This package is provided under the MIT License. You can find the license details in the LICENSE file included with the package.

Contributions

Contributions and improvements to this package are welcome. If you encounter any issues or have ideas for enhancements, please open an issue or submit a pull request on the package's GitHub repository.

Author

This package was created by Iago Calazans. You can contact the author at [email protected] for any questions or inquiries.

Enjoy using this package to build and execute complex workflows in your Node.js applications!