I just saw they added a new thing called record to Java 16. Is this not a replacement for a DTO or am I missing something?
I create a DTO class like:
public class TestDTO {
private String testField;
public String getTestField() {
return this.testField;
}
public void setTestField(String test) {
this.testField = test;
}
}
I define a matching record definition like:
public record TestRecordDTO(String testField) {
}
In web, we use DTOs on the back end to pass data to and from the Javascript/Typescript on the front end. It looks like passing to the
front end works, now how do we use it as a model to get the user
input?
You can use them just like the equivalent manually createdYeah, I thought they were trying to make an easier way to do the same thing, I demonstrated the Gson method recognizes them the same for converting to JSON, but it can't send it back, so it can't replace beans for getting web user input unless I'm
data classes.
But there are two caveats:
1) they are immutable (only getter, no setter)
2) the getter does not follow Java bean convention - it is
.xxxx() not .getXxxx()
That may work or may not work with what you need from
your model classes.
Arne
I just saw they added a new thing called record to Java 16. Is this not a replacement for a DTO or am I missing something?
I create a DTO class like:
public class TestDTO {
private String testField;
public String getTestField() {
return this.testField;
}
public void setTestField(String test) {
this.testField = test;
}
}
I define a matching record definition like:
public record TestRecordDTO(String testField) {
}
Now I try to test them:
public static void main(String[] args) {
TestRecordDTO rec = new TestRecordDTO("testrec");
TestDTO dto = new TestDTO();
dto.setTestField("testrec");
Gson gson = new Gson();
System.out.println(gson.toJson(rec)); // {"testField":"testrec"}
System.out.println(gson.toJson(dto)); // {"testField":"testrec"}
rec.testField();
dto.getTestField();
dto = gson.fromJson(gson.toJson(dto), TestDTO.class);
System.out.println(dto.getTestField()); // testrec
rec = gson.fromJson(gson.toJson(rec), TestRecordDTO.class); // throws AssertionError
System.out.println(rec);
}
In web, we use DTOs on the back end to pass data to and from the Javascript/Typescript on the front end. It looks like passing to the front end works, now how do we use it as a model to get the user input?
In web, we use DTOs on the back end to pass data to and from the Javascript/Typescript on the front end. It looks like passing to the front end works, now how do we use it as a model to get the user input?Note: if you do get an exception, you should at least state its message
in your post.
According to the changelog, support for Java records has been added to
Gson in version 2.10: <https://github.com/google/gson/releases?q=2.10&expanded=true>. Switch
to that and you should be good to go.
--
DF.
ResultSet? Front end data is simple if you can instantiate from JSON using gson. Requiring all values final on instantiation will require a very different DTO structure than the legacy apps I've seen.In web, we use DTOs on the back end to pass data to and from the Javascript/Typescript on the front end. It looks like passing to the front end works, now how do we use it as a model to get the user input?Note: if you do get an exception, you should at least state its message
in your post.
According to the changelog, support for Java records has been added to
Gson in version 2.10:
<https://github.com/google/gson/releases?q=2.10&expanded=true>. Switch
to that and you should be good to go.
Aha! So my sample code does work. I hadn't updated my dependencies in a while on my test project. I need to finish that pom and add a site report with the dependency-updates plugin.
I was referencing gson 2.8.6. I switched to 2.10.1 and it solved that error. Now, if we can switch to Java 17 (15+), we use record for all DTOs? This is much more efficient and/or secure than using classes with lombok?
All fields in a record are final, so it can only have the one constructor with parameters for every field? This sounds tedious to instantiate on the back end unless you're using a framework or convenience method that's going to populate, from a
I doubt it's going to be much different than Lombok in terms of
performance or reliability. The only difference I can see is in terms of clarity of intent. If you start your class with `record`, then you make clear for all to see what you intend the class for. The heuristic value
of that is non-zero.
I haven't had the chance to use records in production yet, so I can but mostly speculate. A quick lookup however suggests that you can use
Lombok's @Builder on `record` classes.
--
DF.
In web, we use DTOs on the back end to pass data to and from theNote: if you do get an exception, you should at least state its
Javascript/Typescript on the front end. It looks like passing to
the front end works, now how do we use it as a model to get the
user input?
message in your post.
According to the changelog, support for Java records has been added
to Gson in version 2.10:
<https://github.com/google/gson/releases?q=2.10&expanded=true>.
Switch to that and you should be good to go.
Aha! So my sample code does work. I hadn't updated my dependencies in
a while on my test project. I need to finish that pom and add a site
report with the dependency-updates plugin. I was referencing gson
2.8.6. I switched to 2.10.1 and it solved that error. Now, if we can
switch to Java 17 (15+), we use record for all DTOs? This is much
more efficient and/or secure than using classes with lombok?
All fields in a record are final, so it can only have the one
constructor with parameters for every field? This sounds tedious to instantiate on the back end unless you're using a framework or
convenience method that's going to populate, from a ResultSet? Front
end data is simple if you can instantiate from JSON using gson.
Requiring all values final on instantiation will require a very
different DTO structure than the legacy apps I've seen.
The Lombok thing was invented to autogenerate the
trivial code.
Scala and Kotlin has case class and data class
respectively to do it simpler.
Java after many years got the record thing.
If you can live with the immutable aspect
(which is sort of in fashion today), then
it would make sense to use them for all
sorts of data classes.
Arne
I just saw they added a new thing called record to Java 16. Is this not a replacement for a DTO or am I missing something?
I create a DTO class like:
public class TestDTO {
private String testField;
public String getTestField() {
return this.testField;
}
public void setTestField(String test) {
this.testField = test;
}
}
I define a matching record definition like:
public record TestRecordDTO(String testField) {
}
Now I try to test them:
public static void main(String[] args) {
TestRecordDTO rec = new TestRecordDTO("testrec");
TestDTO dto = new TestDTO();
dto.setTestField("testrec");
Gson gson = new Gson();
System.out.println(gson.toJson(rec)); // {"testField":"testrec"}
System.out.println(gson.toJson(dto)); // {"testField":"testrec"}
rec.testField();
dto.getTestField();
dto = gson.fromJson(gson.toJson(dto), TestDTO.class);
System.out.println(dto.getTestField()); // testrec
rec = gson.fromJson(gson.toJson(rec), TestRecordDTO.class); // throws AssertionError
System.out.println(rec);
}
In web, we use DTOs on the back end to pass data to and from the Javascript/Typescript on the front end. It looks like passing to the front end works, now how do we use it as a model to get the user input?
Sounds like a record is a class with public final variables.In web, we use DTOs on the back end to pass data to and from the Javascript/Typescript on the front end. It looks like passing to the front end works, now how do we use it as a model to get the user input?I encountered this when I Googled how to do structs in Java. The answer
was not before 16 (though really, a class with a bunch of public
variables will do, if that's what you need).
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