Introduction to Constraints and Notes in Class Diagram

In the next video, you will be introduced to the concept of constraints.

In the previous video, you learnt about constraints, which refer to the conditions that must be preserved while writing code for that class. For example, if you want that userId for every user must be 8 characters long, then such condition you can specify a class diagram as shown below.

Video Transcript

Constraints often in a class which has attributes, there could be some constraints which we would like to enforce. For example, the number of characters that an order can contain or the user ID length. Such constraints can be represented in a class diagram between a closed braces. It can be represented in a natural language or in a programming language too, but it's a free text which can be represented with each attribute within the braces.

Video Recap

 Constraints in a class are rules that enforce limits on attributes.

• Constraints can be represented in a class diagram using braces.

• These constraints can be expressed in natural or programming language.

• Constraints help to limit the values that an attribute can take.

• Examples of constraints include character limits or length limits for user IDs.

Learn how to enforce constraints on attributes in a class diagram with braces. Constraints can limit the values an attribute can take, such as character or length limits. Express constraints in natural or programming language for easy implementation.

In the next video, you will learn about notes.

In the previous video, you learnt about notes, which are used to write decisions or assumptions made while designing your system. For example, while designing your system you decided that you will save placed orders in a database table called "incomplete_orders". Such decisions can be noted down in the class diagram as shown below.