如何检查输入的数字是否为空？

Question

I have this input field in a form which I validate using spring boot validator:

<input class="form-control" th:field="*{numericField}"
    type="number" min="0" id="numeric_field_input">

The valid range is all positive numbers. But even if I do not fill in any number, the field validates. I believe the default value is zero. Adding something like

th:default="-1"

did not solve the problem. How can I check on serverside that a user input any value?

These are my current annotations of the field:

   @Positive(message = "{validation.numericField.positive}")
   @ColumnDefault("0")
   private Integer numericField;

Answer 1

You can use these 2 validations

@NotNull("message": "numericField: positive number value is required")

@Min(value=0, message="numericField: positive number, min 0 is required")

Answer 2

You can use min constraint to limit values be only positive numbers

//import javax.validation.constraints.Min;

@Min(value = 0, message = "numericField not be negative")
 private Integer numericField;

Answer 3

_{Migrating OP's ultimate solution from the question to an answer:}

This is the final way how [sic] I fixed it:

 @NotNull(message = "{validation.numericField.positive}") @Positive(message = "{validation.numericField.positive}") private Integer numericField;