Conditional bean creation in Spring Boot - Step-by-Step Execution

Concept Flow - Conditional bean creation

Start Application

↓

Check Condition on Bean

↓

Create Bean

↓

Continue Application Startup

Spring Boot checks a condition before creating a bean. If the condition is true, the bean is created; otherwise, it is skipped.

Execution Sample

Spring Boot

@Bean
@ConditionalOnProperty(name = "feature.enabled", havingValue = "true")
public MyService myService() {
    return new MyService();
}

This code creates the MyService bean only if the property 'feature.enabled' is set to 'true'.

Execution Table

Step	Action	Condition Checked	Condition Result	Bean Created
1	Start application context	N/A	N/A	No
2	Evaluate @ConditionalOnProperty for 'feature.enabled'	Is 'feature.enabled' == 'true'?	True	Yes, create MyService bean
3	Register MyService bean in context	N/A	N/A	Yes
4	Continue application startup	N/A	N/A	Beans ready
5	Application ready to use	N/A	N/A	Yes

💡 Bean creation depends on condition; if false, bean is skipped and not registered.

Variable Tracker

Variable	Start	After Step 2	After Step 3	Final
feature.enabled	undefined	true	true	true
MyService bean	not created	evaluated	created	created

Key Moments - 2 Insights

Why is the MyService bean not created if the property 'feature.enabled' is false or missing?

Because @ConditionalOnProperty checks the property value at Step 2 in the execution_table. If the condition is false, the bean creation is skipped as shown in the flow.

Can multiple beans use different conditions to control their creation?

Yes, each bean can have its own @Conditional annotation with different conditions, so Spring evaluates each separately during startup.

Visual Quiz - 3 Questions

Look at the execution table, at which step is the condition for bean creation evaluated?

A Step 2

B Step 3

C Step 1

D Step 4

💡 Hint

Check the 'Condition Checked' column in the execution_table.

If the property 'feature.enabled' is set to false, what happens to the MyService bean?

A It is created anyway

B It is not created

C It is created but disabled

D Application fails to start

💡 Hint

Refer to the 'Condition Result' and 'Bean Created' columns in the execution_table.

If you add another bean with a different condition, how does Spring handle bean creation?

A It only creates the first bean with a true condition

B It creates all beans regardless of conditions

C It evaluates each bean's condition separately

D It throws an error if multiple conditions exist

💡 Hint

See key_moments about multiple beans and conditions.

Concept Snapshot

Conditional bean creation in Spring Boot:
- Use @Conditional annotations (e.g., @ConditionalOnProperty)
- Spring checks condition during startup
- Bean is created only if condition is true
- Skips bean creation if condition is false
- Allows flexible, environment-based bean setup

Full Transcript

Conditional bean creation in Spring Boot means the framework decides whether to create a bean based on a condition. For example, using @ConditionalOnProperty, Spring checks if a property is set to a specific value. If true, it creates the bean; if false, it skips it. This happens during application startup. This approach helps to enable or disable features easily without changing code. Each bean can have its own condition, and Spring evaluates them one by one. This makes your application flexible and configurable.