Mastering Swagger: Configuring allowableValues in @ApiModelProperty

When generating API documentation with Swagger, the @ApiModelProperty annotation can describe a field's allowed values via its allowableValues attribute, which is a String. There are three ways to specify these values:

Provide a comma‑separated list, e.g., "first, second, third".

Define a numeric range using the range keyword with square brackets for inclusive bounds or parentheses for exclusive bounds, e.g., "range[1,5]", "range(1,5)", "range[1,5)".

Set a minimum or maximum using range with infinity (or -infinity) as one bound, e.g., "range[1,infinity]" meaning the minimum is 1.

The annotation definition looks like this:

public @interface ApiModelProperty {
    /**
     * Limits the acceptable values for this parameter.
     * <p>
     * There are three ways to describe the allowable values:
     * <ol>
     *   <li>To set a list of values, provide a comma‑separated list.</li>
     *   <li>To set a range of values, start the value with "range" and use square or round brackets.</li>
     *   <li>To set a minimum/maximum value, use the same format with "infinity" or "-infinity".</li>
     * </ol>
     */
    String allowableValues() default "";
    ...
}

In practice you can apply it as follows:

public class Filter {
    @ApiModelProperty(allowableValues = "range[1,5]")
    Integer order;

    @ApiModelProperty(allowableValues = "111, 222")
    String code;
}

After rebuilding the project, the Swagger UI correctly displays the configured allowed values. The screenshot below shows the result.