Unlocking the Power of Command Query Separation: OrganizationBed Case Study

Command Query Separation (CQS) is a programming paradigm that separates the responsibilities of a class into two distinct types of methods: commands and queries. The purpose of this separation is to make code more readable, maintainable, and testable by clearly defining the intent of each method.

In this blog post, we will be looking at an example class called OrganizationBed, and how it can be implemented using the CQS pattern. The class has the following properties:

• Id: a unique identifier for the bed
• Index: the index of the bed in the organization
• Description: a description of the bed
• OrganizationId: the id of the organization that the bed belongs to
• Organization: the organization that the bed belongs to
• Guest: the guest currently occupying the bed
• BedImage: an image of the bed

The first thing we need to do is to identify which methods in the class are commands and which are queries. A command method is one that modifies the state of the object or the system, while a query method is one that returns information about the object or the system without modifying it.

Based on the properties of the class, we can identify the following command methods:

• ChangeBedIndex(int newIndex): changes the index of the bed
• ChangeBedDescription(string newDescription): changes the description of the bed
• AssignBedToGuest(Guest guest): assigns the bed to a guest
• RemoveBedImage(): removes the image of the bed

And the following query methods:

• GetBedId(): returns the id of the bed
• GetBedIndex(): returns the index of the bed
• GetBedDescription(): returns the description of the bed
• GetBedOrganization(): returns the organization that the bed belongs to
• GetBedGuest(): returns the guest currently occupying the bed
• GetBedImage(): returns the image of the bed

With these methods separated, it becomes much easier to understand the intent of each method and what it does. Additionally, it makes it easier to test and maintain the code, as the commands and queries are clearly defined and do not overlap.

It’s worth noting that the above methods are just one possible implementation of CQS pattern and the methods could be changed or added as per the requirement and best practices.

In conclusion, the Command Query Separation (CQS) pattern is a powerful tool for making code more readable, maintainable, and testable. By clearly separating commands and queries in a class, developers can create code that is easy to understand and work with. The OrganizationBed class is a good example of how CQS can be implemented in practice.