Hi Everyone! I have one easy question How i can write @NotNull, @NotEmpty and @NotBlank in kotlin

# spring

[Hamza GATTAL]

Hi Everyone!
I have one easy question

How i can write @NotNull, @NotEmpty and @NotBlank in kotlin

[Emil Kantis]

@get:NotNull etc. Although I'm not sure why you would need @NotNull 🙂

[Emil Kantis]

another option is using init { require(someStringProperty.isNotEmptyOrBlank()) } , but that doesn't follow Spring conventions I suppose

[Hamza GATTAL]

I'm converting a Java code to kotlin

[Ben]

@Emil Kantis Jackson will set non-nullable fields to null using reflection.

[thanksforallthefish]

personally I’d rather have the json representation accepts nulls and being annotated with @NotNull than having the field not-nullable, it makes for easier and better error message given the stack I use (spring boot, web and validation). @NotNull generates a validation exception which I can treat as all other validations exceptions, which not-nullable field is a kotlin binding error, which needs special treatment. eg

class SomeApiRepresentation(@get:NotNull aNotNullableField: String?)

the price of course is !!, but I am not a purist, and in this case !! is fine with me

[Thomas]

I also would vote for @thanksforallthefish’s approach, as a field with null value is a possible input and only validation may fail. You can have a look at bootify.io, it generates a REST controller for a Kotlin/Spring project