Can We Use @Arrayschema In Response?

Introduction

In the world of API documentation, using the right annotations can make a significant difference in how our APIs are perceived by developers and users. In this article, we will explore the use of @ArraySchema in response and whether it can be used effectively in our APIs.

Describe the Bug

When using @ArraySchema annotation in a List<T>, it loses schema information. This can be a significant issue, especially when we need to provide detailed information about the data being returned in our API responses.

What Version of Spring-Boot Are You Using?

In this case, we are using Spring-Boot version 2.8.8.

Sample Code

To reproduce the problem, we can use the following sample code:

package test.org.springdoc.api.v31.app19

import io.swagger.v3.oas.annotations.media.ArraySchema
import io.swagger.v3.oas.annotations.media.Schema
import org.springframework.boot.autoconfigure.SpringBootApplication
import org.springframework.web.bind.annotation.GetMapping
import org.springframework.web.bind.annotation.RequestMapping
import org.springframework.web.bind.annotation.RestController
import test.org.springdoc.api.v31.AbstractKotlinSpringDocMVCTest

class SpringDocApp19Test : AbstractKotlinSpringDocMVCTest() {
    @SpringBootApplication
    class DemoApplication
}

@RestController
@RequestMapping("/test")
class HelloController {

    @GetMapping
    fun index(): R<Page<User>> = TODO()
}

@Schema(description = "R Description")
data class R<T>(
    @Schema(description = "code Description")
    val code: Int,
    @Schema(description = "message Description")
    val message: String,
    @Schema(description = "data Description")
    val data: T
)

@Schema(description = "Page Description")
data class Page<T>(
    @Schema(description = "total Description")
    val total: Int,
    @ArraySchema(schema = Schema(description = "use @ArraySchema will lost User Info"))
//    @Schema(description = "list Description")
    val list: List<T>
)

@Schema(description = "User Description")
data class User(
    @Schema(description = "name Description")
    val name: String?,
    @Schema(description = "age Description")
    val age: Int
)

Expected Behavior

The expected behavior is that using @ArraySchema annotation should not lose schema information.

Screenshots

Analysis

After analyzing the code, it appears that the issue is due to the way @ArraySchema is being used in the Page class. When we use @ArraySchema in a List<T>, it loses schema information because the schema attribute is not being used correctly.

Solution

To fix this issue, we need to use the schema attribute correctly. We can do this by creating a separate Schema object for the User class and then using that schema in the ArraySchema annotation.

Here's the updated code:

@Schema(description = "User")
data class User(
    @Schema(description = "name Description")
    val name: String?,
    @Schema(description = "age Description")
    val age: Int
)

@Schema(description = "User Schema")
data class UserSchema(
    @Schema(description = "name Description")
    val name: String?,
    @Schema(description = "age Description")
    val age: Int
)

@Schema(description = "Page Description")
data class Page<T>(
    @Schema(description = "total Description")
    val total: Int,
    @ArraySchema(schema = UserSchema::class)
    val list: List<T>
)

Conclusion

In conclusion, using @ArraySchema in response can be effective, but it requires careful usage of the schema attribute. By creating a separate Schema object for the User class and using that schema in the ArraySchema annotation, we can fix the issue and provide detailed information about the data being returned in our API responses.

Best Practices

Here are some best practices to keep in mind when using @ArraySchema in response:

• Use the schema attribute correctly by creating a separate Schema object for the data type.
• Use the ArraySchema annotation in a List<T> to provide detailed information about the data being returned.
• Test your API responses thoroughly to ensure that the schema information is being provided correctly.

Q: What is the purpose of @ArraySchema in response?

A: The purpose of @ArraySchema in response is to provide detailed information about the data being returned in a list. It allows you to specify the schema of the data type, which can be useful for API documentation and testing.

Q: Why does @ArraySchema lose schema information when used in a List?

A: The issue is due to the way @ArraySchema is being used in the List<T>. When you use @ArraySchema in a List<T>, it loses schema information because the schema attribute is not being used correctly.

Q: How can I fix the issue with @ArraySchema losing schema information?

A: To fix the issue, you need to use the schema attribute correctly. You can do this by creating a separate Schema object for the data type and then using that schema in the ArraySchema annotation.

Q: What is the difference between @ArraySchema and @Schema in response?

A: @ArraySchema is used to specify the schema of a list, while @Schema is used to specify the schema of a single data type. @ArraySchema is typically used when you need to provide detailed information about the data being returned in a list.

Q: Can I use @ArraySchema in response with other annotations?

A: Yes, you can use @ArraySchema in response with other annotations. For example, you can use it with @Schema to provide additional information about the data type.

Q: How can I test my API responses to ensure that the schema information is being provided correctly?

A: You can test your API responses using tools like Postman or cURL. You can also use API testing frameworks like JUnit or TestNG to write unit tests for your API responses.

Q: What are some best practices for using @ArraySchema in response?

A: Here are some best practices to keep in mind when using @ArraySchema in response:

• Use the schema attribute correctly by creating a separate Schema object for the data type.
• Use the ArraySchema annotation in a List<T> to provide detailed information about the data being returned.
• Test your API responses thoroughly to ensure that the schema information is being provided correctly.

Q: Can I use @ArraySchema in response with Spring Boot?

A: Yes, you can use @ArraySchema in response with Spring Boot. Spring Boot provides a number of annotations and tools that can be used to document and test your API responses.

Q: What are some common use cases for @ArraySchema in response?

A: Here are some common use cases for @ArraySchema in response:

• Providing detailed information about the data being returned in a list.
• Specifying the schema of a list to ensure that the data is being returned correctly.
• Testing API responses to ensure that the schema information is being provided correctly.

By these best practices and use cases, you can effectively use @ArraySchema in response to provide detailed information about the data being returned in your API responses.