How to map Date and Time fields in REST applications

This article will teach you the simplest way to map Date and Time fields in an Entity when the request/response is from a REST Endpoint.

Defaults for Date / Time in REST Application

When your REST Endpoint exposes some Data and Time fields in JSON Format, you can mainly use two formats:

A java.sql.Date format, which by default uses the format yyyy-mm-dd

A javasql.Timestamp format, which by default uses the format yyyy-mm-ddThh:mm:ss

Here is a sample Entity which uses both Date and Time formats:

@Entity
public class Car {
	@Id
	@GeneratedValue(strategy = GenerationType.UUID)
	private UUID id;
	
	private java.sql.Date dateProd;		
	private java.sql.Timestamp timeProd;  
 
}

Then, you can let JSONB handle the automatic mapping between Java and JSON by exposing an Endpoint which Consumes and Produces JSON data:

@POST
@Consumes(MediaType.APPLICATION_JSON)
@Produces(MediaType.APPLICATION_JSON)
public Response createCar(Car car) {

	Response.ResponseBuilder builder = null;

	try {
		ejb.save(car);
		builder = Response.ok("Saved!");

	} catch (Exception e) {
		// Handle generic exceptions
		Map<String, String> responseObj = new HashMap<>();
		responseObj.put("error", e.getMessage());
		builder = Response.status(Response.Status.BAD_REQUEST).entity(responseObj);
	}

	return builder.build();
}

Then, you can insert both Date and Time as text Strings using the default formats. For example, using Postman:

Otherwise, using plain cURL:

curl -X POST http://localhost:8080/jpa-basic/rest/carservice  -H 'Content-Type: application/json' -d ' {"model":"fiat","price":"15090.10","dateProd":"2021-12-25", "timeProd":"2020-05-01T12:30:00"}'

Using a custom JSONBDateFormat

When your REST data uses a custom format for Date or Time then you can use the @jakarta.json.bind.annotation.JsonbDateFormat annotation to map your in/out fields. For example:

@JsonbDateFormat(value = "MM/dd/yyyy")
private Date dateProd;

@JsonbDateFormat("dd-MM-yyyy'T'HH:mm:ss")	
private Timestamp timeProd;

With the above mapping, you will be able to issue the following Request for your REST Endpoint:

curl -X POST http://localhost:8080/jpa-basic/rest/carservice  -H 'Content-Type: application/json' -d ' {"model":"fiat","price":"15090.10","dateProd":"2021-12-25", "timeProd":"2020-05-01T12:30:00"}'

Besides, you can also include the optional locale attribute to set the Locale for your date:

@JsonbDateFormat(value = "MM/dd/yyyy", locale = "Locale.ENGLISH"))
private Date dateProd;

@JsonbDateFormat("dd-MM-yyyy'T'HH:mm:ss", locale = "Locale.ENGLISH"))	
private Timestamp timeProd;

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