---
title: "SDK: Flow Steps (Basic)"
slug: "flow-steps-simple"
description: "This document demonstrates the basics in creating Flow Steps within Visual Studio by writing code that references Decisions. The document explains this further with an example that demonstrates how to build code that tests the validity of a zip code. "
tags: ["Flow Step", "SDK Basic", "SDK"]
updated: 2024-12-11T19:39:20Z
published: 2024-12-11T19:39:20Z
---

> ## Documentation Index
> Fetch the complete documentation index at: https://documentation.decisions.com/llms.txt
> Use this file to discover all available pages before exploring further.

# SDK: Flow Steps (Basic)

## Overview

Developers can easily create custom Flow and Rule steps by methods in a **Class Library (.NET Core) project**. This article will show users how to accomplish this. For more examples

Prerequisites

- Knowledge of the desired integrated development environment (IDE) for development
- Understanding of SDK in Decisions. To learn more, visit [SDK Overview](https://documentation.decisions.com/v9/docs/sdk-overview) and [SDK Basics](https://documentation.decisions.com/v9/docs/project-sdk-extensions).
- Custom steps will be located and stored at **C:\Program Files\Decisions\Decisions Server\modules\Decisions.Local\CoreServiceDlls**

---

## Basic Flow Step

The below code example will create a Flow step that checks if a string is 5 digits long. For more examples, check the [Public GitHub Repository](https://github.com/decisions-com/sdk-examples) for Decisions.

This code uses the **AutoRegisterMethodsOnClass** attribute, which will allow the code to show as a Flow step in the Steps panel.****This attribute and others are further explained in the [AutoRegister Attribute Glossary](https://documentation.decisions.com/v9/docs/autoregister-attributes) article.

```csharp

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using DecisionsFramework.Design.Flow;

namespace ShippingExtensions
{
    [AutoRegisterMethodsOnClass(true, "SDK/ZipCode")]
    public class ZipCodeManagement
    {
        public bool IsZipCodeValid(string zipCode) {
            if (zipCode.Length ==5) {
                foreach (char eachChar in zipCode.ToCharArray()) {
                    if (Char.IsDigit(eachChar) == false) {
                        return false;
                    }
                }
                return true;
            }
            return false;
        }
    }
}
```

| Code Snippet | What it does |
| --- | --- |
| using DecisionsFramework.Design.Flow | Decisions reference |
| [AutoRegisterMethodsOnClass(true, "SDK/ZipCode")] | This attribute will allow the code to show as a Flow step in the Steps panel. "SDK/ZipCode" will be the categories that this step is nested in within. |
| IsZipCodeValid(string zipCode) | This will be the name of the step and (string zipCode) will be the input. |
| return true | The output of this step |
| return false | The output of this step |

---

## Using the Method in Decisions

After writing the method to build the project, add it to Decisions by following the steps in [Software Development Kit (SDK) Overview](https://documentation.decisions.com/v9/docs/sdk-overview).

Custom code needs to be saved here: **C:\Program Files\Decisions\Decisions Server\modules\Decisions.Local\CoreServicesDlls**

1. [Create a new Flow](/v9/docs/create-flows).
2. In the **Steps**panel, navigate to **SDK > ZipCode.**  
![](https://cdn.document360.io/6ef8bcc1-6489-4486-9ad1-83acff7e5df0/Images/Documentation/2024-08-22_16h58_21.png)
3. Drag and drop the custom **Is Zip Code Valid** step onto the workspace.
4. This step displays as a Rule step with a True and False outcome as stated in the method written. The step also has the Zip Code input that is expecting a string.
5. Click **Unknown**and select **Constant**as the mapping type, and type in a 5-digit zip code.  
![](https://cdn.document360.io/6ef8bcc1-6489-4486-9ad1-83acff7e5df0/Images/Documentation/2024-08-22_17h00_04.png)
6. Click **Save**to save changes to the Flow.

---

## Debug

1. Click **Debug**on the top action bar. In the debugger, the Flow runs using "23322" as the input for the Rule step, and the step outputs as True.  
![](https://cdn.document360.io/6ef8bcc1-6489-4486-9ad1-83acff7e5df0/Images/Documentation/2024-08-22_17h01_00.png)

---

For further information on SDK, visit the [Decisions Forum](https://community.decisions.com/categories/SDK).