7.13 Correctly use Validation to implement parameter validation in SpringBoot

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Preface

Let’s talk about Spring Validation parameter verification first. It is one of the tasks that must be done by the SpringBoot backend Controller layer of the front-end and back-end separation project. The purpose is to prevent illegal calls. The Java JSR303verification standard is defined validation-apibut not implemented. Hibernate validation is a standardized implementation. In addition, some annotations were added constraints, and finally a secondary encapsulation was Spring Validationperformed Hibernate validationto support automatic verification in SpringMvc!

So, now that the Restful style is popular, in SpringBoot, the mainstream parameter verification scenarios include:

1. For POSTrequests PUT, use the parameters passed by @RequestBody to verifyVO对象
2. For GET、DELETErequests, use the parameters passed by @RequestParamurl拼接 to verify
3. Unannotated parameter verification for GET requests

Next, I will show you the correct use of @Valid , @Validated and constraints with a combination of pictures and texts. They must be used in work and practiced in practice. Finally, there is a summary , Let's Go!

The constraints annotation defined by Java's standard is located at: javax.validation.constraints

The constraints annotations added to Hibernate validation are located at: org.hibernate.validator.constraints

The perfect partner for parameter verification: 7.11 SpringBoot practical global exception handling - in-depth explanation

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Introduce Maven dependencies

Before springboot2.3 , dependencies spring-boot-starter-webwere automatically introduced when introduced.validation

But after springboot2.3 , dependencies need to be introduced separatelyspring-boot-starter-validation

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-validation</artifactId>
</dependency>

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1. POST/PUT @RequestBody parameter verification

For POSTrequests PUT, it is preferred to use @RequestBodypass VO对象parameters.

1.1 Valid or Validated annotation combined with constraints annotation

Take BookAdminController's saveBook as an example:

• Add annotations before method parameters @Valid( @Validatedyou can also replace them with annotations):

• Add annotations BookVOto the fields of the object , for example, add an annotation toconstraintsbookName@NotNull

1.2 Test run

If the input parameters are not filled in bookName, they will be caught by the exception of parameter verification exceptionMethodArgumentNotValidException , and finally the result shown in the figure above will be returned~

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2. GET/DELETE @RequestParam parameter verification

For GET、DELETErequests, it is preferred to use @RequestParampassed url拼接parameters.

2.1 Validated annotation and constraints annotation

Take BookAdminController's getBook as an example:

At this time, you need to add annotations to the Controller and add annotations @Validatedbefore the method parameters . Take annotations as an example:constraints@Min

2.2 Test run

Because @Minthe minimum value is limited to 1, when calling with input id=0parameters, it will be caught by the parameter verification exception exception ConstraintViolationException:

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3. GET unannotated parameter verification

constraintsAdd annotation before @RequestParam . It can be used if there are few parameters. When there are many parameters, it is recommended to encapsulate it into a VO object. The calling method remains the same~

3.1 Valid or Validated annotation combined with constraints annotation

Taking the getBookCommentList of BookAdminController as an example, it was originally written like this:

Now the parameters are encapsulated into an PageVOobject, and annotations are added to the fields constraints: @Min, @Max,@NotNull

@Data
public class PageVO implements Serializable {
    
    
    @Min(value = 1, message = "pageNum必须大于1")
    private Integer pageNum = 1;

    @Max(value = 100, message = "pageSize不能超过100")
    private Integer pageSize = 100;

    @Min(value = 1, message = "id必须大于1")
    @NotNull
    private Integer id;
}

At this time, in the same way as @RequestBody parameter verification and annotation, add @Validannotations to the method parameters ( @Validatedyou can also change to annotations):

3.2 Test run

Because @Maxthe maximum value of pageSize is limited to 100, when calling with input pageSize=1000parameters, it will be caught by the exception of parameter verificationBindException exception:

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Summarize

• @ValidPOST/PUT @RequestBody parameter verification, add or before the method parameter VO , and add relevant comments @Validatedto the VO fieldconstraints
• GET/DELETE @RequestParam parameter verification, add it on the Controller , and add relevant comments @Validatedbefore the method parameters.constraints
• @ValidGET has no annotation parameter verification, add or before the method parameter VO , and add relevant annotations @Validatedto the VO field.constraints

For constraintsrelevant details, I have found two articles for your reference:

Powerful Spring's spring validation

Detailed explanation of Hibernate Validator

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at last

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