How To use Model OOP in Java - java

I have a Model Active Admin, I have created String ID setter and getter.
When I use setID in Login Form, I use this :
ActiveAdmin AA = new ActiveAdmin();
AA.setId(txtIdAdmin.getText());
When I test getter from login form, it works. When I test in another form, in another Java class, in different file, I can't get my string ID in Active Admin. I used:
AA.getId();
And the result is blank.

Build ActiveAdmin as a Singleton class, such that you have one instance for the entire application. Otherwise you will build a new object ActiveAdmin everytime when you use new ActiveAdmin().
Check link Java Singleton

Muhamad, setters and getters for properties typically take this form, based on what I think you're saying:
public class ActiveAdmin
{
public string Id { get; set; }
}
From another class, you would say "aA = new ActiveAdmin();"
Then aA.Id = "2"; and string aAId = aA.Id;

Related

ModelMapper DTO-->Entity. How to skip unconditionally all fields not mapped

I have two classes (entity and DTO)
public class Deliver {
private Long id;
private String uri;
private Instant moment;
private DeliverStatus status; // enum PENDING,ACCEPTED,REJECTED
private String feedback; // feedback about received task
private Integer correctCount; // nr of correct questions
private Enrollment enrollment;
private Lesson lesson;
// constructors, getters and setters..
public class DeliverRevisionDto {
private DeliverStatus status;
private String feedback;
private Integer correctCount;
// constructors, getters and setters..
The goal is pretty simple, update the entity fields conveyed by Dto class I have the following code at Service layer (Spring Boot version 2.4.4):
#Service
public class DeliverService {
#Autowired
private DeliverRepository deliverRepository;
#Autowired
private ModelMapper modelMapper;
#Transactional
public void saveRevision(Long id, DeliverRevisionDto dto) {
Deliver deliver = deliverRepository.getOne(id);
System.out.println("BEFORE MAPPING: " + deliver.toString()); // # debug purpose
deliver = modelMapper.map(dto, Deliver.class);
// # debug purpose
TypeMap<DeliverRevisionDto, Deliver> tm = modelMapper.getTypeMap(DeliverRevisionDto.class, Deliver.class);
List<Mapping> list = tm.getMappings();
for (Mapping m : list)
{
System.out.println(m);
}
System.out.println("AFTER MAPPING: " + deliver.toString()); // # debug purpose
deliverRepository.save(deliver);
}
}
The console output is:
BEFORE MAPPING: Deliver [id=1, uri=``https://github/someone.com``, moment=2020-12-10T10:00:00Z, status=PENDING, feedback=null, correctCount=null, enrollment=com.devsuperior.dslearnbds.entities.Enrollment#7e0, lesson=com.devsuperior.dslearnbds.entities.Task#23]`
`PropertyMapping[DeliverRevisionDto.correctCount -> Deliver.correctCount]`
`PropertyMapping[DeliverRevisionDto.feedback -> Deliver.feedback]`
`PropertyMapping[DeliverRevisionDto.status -> Deliver.status]`
`AFTER MAPPING: Deliver [id=null, uri=null, moment=null, status=ACCEPTED, feedback=Muito bem cabra, tarefa aceita., correctCount=5, enrollment=null, lesson=null]
The mapping of the 3 fields in DTO is done correctly, BUT all the other fields of my entity are set to null. I know that I can skip fields according http://modelmapper.org/user-manual/property-mapping/
The problem is that I don´t want to couple the code with specific field names/getters/setters, that´s the reason I´m using ModelMapper. I wonder if there is any configuration that, upon mapping the modelmapper object says "Hey, the TARGET class have way more fields than the SOURCE class, I will left them untouched unconditionally (meaning I don´t need to say what fields are).
I'm trying to map fields between 2 classes with different set of fields (some are the same), and when I map the class with smaller set of fields to the one with bigger set of fields, the mapper set fields that don´t match with "null", I want these fields untouched (with original values) without I telling which one they are, after all, the mapper knows which ones match.
ModelMapper documentation is not the best part of that framework. Let us see what happens in your code.
Here you fetch the entity to be updated from the repo:
Deliver deliver = deliverRepository.getOne(id);
and log it having all the fields as should be. However this line:
deliver = modelMapper.map(dto, Deliver.class);
does a re-assignment to your variable deliver. This method creates a new instance of Deliver class and assigns it to variable deliver so discarding the entity fetched from repo.
This new instance will have all the fields that are not existing or not set in DTO null.
This is the API doc that my IDE provides, fotr these two different methods:
String org.modelmapper.ModelMapper.map(Object source, Class destinationType)
Maps source to an instance of destinationType. Mapping is performed according to the corresponding TypeMap. If no TypeMap exists for source.getClass() and destinationType then one is created.
Versus
void org.modelmapper.ModelMapper.map(Object source, Object destination)
Maps source to destination. Mapping is performed according to the corresponding TypeMap. If no TypeMap exists for source.getClass() and destination.getClass() then one is created.
It might not be clearly stated that the first method actually creates a new instance based on the type (Class) passed but it should be clear that ModelMapper cannot alter some arbitrary variable just by knowing the type. You need to pass the variable to alter as method parameter.

Design for large scale parameter validation for JPA?

I have a method that takes in a JSON and takes out the data and distributes it to various strings so that they can be set in an entity and persisted. My example below is quite simple but for my actual code I have about 20+ fields
For example see
public Projects createProject(JsonObject jsonInst) {
Projects projectInst = new Projects();
String pId = jsonInst.get("proId").getAsString();
String pName = jsonInst.get("proName").getAsString();
String pStatus = jsonInst.get("proStatus").getAsString();
String pCustId = jsonInst.get("proCustId").getAsString();
String pStartDate = jsonInst.get("proStartDate").getAsString();
...
//Set the entity data
projectInst.setProjectId(pId);
projectInst.setProjectName(pName);
...
Notice if a varible dosent have a corrosponding entry in the Json this code will break with null pointer exception. Obviously I need to validate each parameter befopre calling .getAsString()
What is the best way to do this from a readability point of view I could create 2 varibles for each parameter and check and set for example.
if(jsonInst.get("proName")){
String pName = jsonInst.get("proName").getAsString();
}
Or should I wait for it to be set
if(!pName.isEmpty()){
projectInst.setName(pName)
}
...
Which of these do you think is the best parameter to use for preventing errors.
Is there a way to handle if something is set on a large scale so that I can reduce the amount of code I have to write before I use that varible?
You can create a method that will take field name as parameter and will return json value for that field :
private String getJSONData(String field,JsonObject json){
String data=null;
if(json.has(field)){
data=json.get(field).getAsString();
}
return data;
}
you can call this method for each of your field:
String pId = getJSONData("proId",jsonInst);
By this way you can not only escape NullPointerException, but also avoid code repetition.

sending javascript object arrays as parameters to controller

Question is pretty self explanatory. I want to send 2 different arrays of objects through a POST form without ajax to my controller.
I changed my question to using ajax and using a get request due to the size of the params. Currently getting a 400 (Bad Request). I have no idea why. Please take a look...
I have objects:
var phone = {phoneId:"", phoneNumber:"", phoneType:""};
var schedule = {scheduleId:"", time:"", day:""};
Which I place into a javascript arrays:
var phones = [phone1, phone2, phone3];
var schedules = [schedule1, schedule2];
and I use ajax to send:
var data = {
index: id,
schedules: schedules,
phones: phones
}
var url = "/myController/myUrl"
$.getJSON(url, data, function(result){
if(result.ok){
$('#messageAlertSuccess').show();
} else {
$('#messageAlertError').show();
}
});
I created wrapping classes to map them like so:
public class PhoneWrapper(){
private String phoneId;
private String phoneNumber;
private String phoneType;
}
And of course the scheduleWrapper follows the same convention.
Here's the method in my controller:
#ResponseBody
#RequestMapping(value="/myUrl", method=RequestMethod.GET)
public Result doSomething(#RequestParam("index") int index,
#RequestParam("phones") Set<PhoneWrapper> phoneWrappers,
#RequestParam("schedules") Set<ScheduleWrapper> scheduleWrappers,
Model model,
HttpSession session){
//do stuff here.
}
I am currently getting a 400. So what's wrong?
Update: here's the url that the .getJSON jquery method is building:
http://localhost:8080/myApp/myController/myUrl?index=9&schedules%5B0%5D%5BscheduleId%5D=1&schedules%5B0%5D%5BfromDay%5D=Monday&schedules%5B0%5D%5BtoDay%5D=Friday&schedules%5B0%5D%5BfromTime%5D=08%3A30%3A00&schedules%5B0%5D%5BtoTime%5D=16%3A00%3A00&schedules%5B1%5D%5BscheduleId%5D=5&schedules%5B1%5D%5BfromDay%5D=Saturday&schedules%5B1%5D%5BtoDay%5D=Monday&schedules%5B1%5D%5BfromTime%5D=09%3A00%3A00&schedules%5B1%5D%5BtoTime%5D=13%3A00%3A00&phones%5B0%5D%5BphoneId%5D=6&phones%5B0%5D%5BphoneNumber%5D=787-788-1111&phones%5B0%5D%5BphoneType%5D=PHONE&phones%5B1%5D%5BphoneId%5D=106&phones%5B1%5D%5BphoneNumber%5D=787-795-4095&phones%5B1%5D%5BphoneType%5D=FAX
I see a few things that don't look right
unless you have getters and setters in your wrappers (DTO is a better name), i don't use them for my DTOs for xhr calls, you need to change
public class PhoneWrapper(){
private String phoneId;
private String phoneNumber;
private String phoneType;
}
to have public fields vs private
public class PhoneWrapper(){
public String phoneId;
public String phoneNumber;
public String phoneType;
}
Your js arrays are not arrays but objects;
var phones = {phone1, phone2, phone3};
var schedules = {schedule1, schedule2};
Here they are as arrays
var phones = [phone1, phone2, phone3];
var schedules = [schedule1, schedule2];
Make sure you naming is the same of both the js and java sides. I find it very helpful to turn on the debugging when troubleshooting these problems. log4j -
<logger name="org.springframework.web.servlet.mvc" >
<level value="debug" />
</logger>
EDIT
So after the question was updated with more info I notice that it was the same problem as Binding a list in #RequestParam
I would say that you are almost there! The first thing the you need is a wrapper to hold the two Set<> parameters since spring is not able to map a collection directly to parameters (yet?).
Also, there are two ways to handle this kind of requests:
use a json request and #Requestbody with a single javascript object in the request body an map this into a java class (automatically by spring). This means you need to change a little how the data is send down and this approach has one side effect: you cannot merge data simply by defining the parameter as a model attribute.
a second possibility is to stay with the post form submit. Also here you need to create the wrapper and use this one as a requestparam. Either one per Set<> parameter like #Sotirios mentioned in his answer or one parameter which holds both sets. Then you need to modify your submit data to send the phone and schedule information like input fields. I haven't used sets in this case but
lists and the parameter names would look like phoneWrapper[0].phoneId.
The advantage of the second approach is that you can merge the request data with existing values so you do not need to send down a complete phone information all the time.
var phones = {phone1, phone2, phone3};
var schedules = {schedule1, schedule2};
These two are not arrays (square brackets), but objects (curly brackets).
Compare with
var phones = ["phone1", "phone2", "phone3"];
var schedules = ["schedule1", "schedule2"];
and if you are to pass actual object references (phone1, phone2, phone3, schedule1 and schedule2 are object variables) then you need to use
var phones = [phone1, phone2, phone3];
var schedules = [schedule1, schedule2];
For spring the map request parameters to Class instance fields, they have to match the name of the parameter.
So with
<input type="hidden" name="someParameter" value="123"/>
and
public class SomeClass {
private String someParameter;
// getters and setters
}
a Spring controller will be able to be injected with a SomeClass instance whose field someParameter has the value 123 that comes from the html hidden input request parameter. This is also known as a command object.
A javascript array has no meaning to either html or http.
As for the solution, I would keep your class PhoneWrapper, use javascript to populate 3 <input> elements, and change the method definition to
#RequestMapping(value=MY_URL, method=RequestMethod.POST)
public String doSomething(#RequestParam("index") int index,
PhoneWrappers phoneWrappers,
ScheduleWrappers scheduleWrappers,
Model model,
HttpSession session){
Notice there are no more array [] brackets. (You would do the same for ScheduleWrappers).

How to invoke a string from a class using method.invoke(-,-)

Here i am trying to get uContainer object from another project. uContainer having all the setters and getters with return values set from properties file. Like a user properties for perticular user. I am using to get perticular method values from uContainer instance. But in the 4th line my application getting crashed.
uContainer is an instance of UserContainer class.
getSingleResultListing also a boolean variable in UserContainer class having with getters and setters methods.
The code is given below.
Method getUContainer = form.getClass().getMethod("getUserContainer", new Class[0]);
Object uContainerObj = (Object)getUContainer.invoke(form, new Object[0]);
Method getFlagValueMethod = uContainerObj.getClass().getMethod("getSingleResultListing", new Class[0]);
String flagValue = (String)getFlagValueMethod.invoke(uContainerObj, new Object[0]);
log.info(">>>flagValue: "+flagValue);
boolean singleListingFlag = Boolean.getBoolean(flagValue);
log.info(">>>singleListingFlag: "+singleListingFlag);
here in the fourth line while invoking the uContainer object i am getting error ..
Thanks..
You are casting the returned object to a String, but you are not getting a String from that method. You cannot convert objects to String via a cast operator. If you want the string representation, write
String flagValue = getFlagValueMethod.invoke(uContainerObj, new Object[0]).toString();

how to use same string in two java files

Sorry for my bad English and for maybe stupid question but I'm new in Java.
I need use same string in 2 java files for example:
In first java file I've got code for sending emails, I've got string set to default email:
public String mail = new String ("lala#gmail.com");
and I use this string in code for send email:
email.addTo(mail);
In second java file something like set up where can user set new email address I want to have same string, connected with string in first java file. When user put new email String mail will be change to new email address and in email.addTo(mail); will be use this new address
How can I do this?
use Shared Preferences, you can store it as key-value Pair. value being your email and key can be any unique string which you want to identify it with.
I'm a bit confused with the question, but I'll take a stab at it. Basically, you would like to have one String in a given file be used in multiple locations. This is easily done using class-level variables and making them publicly accessible.
For example, in the file:
EmailObject.java
public class EmailObject {
public static final String mail = "lala#gmail.com";
// The rest of your code
}
Another file can access this like so:
OtherObject.java
public void sendEmail() {
EmailMessage email = new EmailMessage();
email.addTo(EmailObject.mail);
}
Note the static and final modifiers on the original. This ensures that you do not need an actual instance of EmailObject to access the string and it also ensures that the string is never modified accidentally by some other object.
There are, of course, other ways to do this, but this one matches your code the most. This is also a very "Java" solution. Android has other ways to share data (as indicated by the other answer).
The simplest way that I would not recommend is to have a public static field:
class A {
public static String commonString;
}
class B {
public void methodThatUsesString () {
// Do stuff with the string
Log.d("I have the string", A.commonString);
}
}
If you have two Activities, and one starts another, you can send data through Intents.
The forementioned SharedPreferences way is a good solution too, if the email address is a persistent thing, a preference if you will, and not just data reqired for an operation.
You can keep a reference of one instance of a class in the otherone, and access it's fields through it:
class A {
public String commonString;
}
class B {
private final A instaceOfA;
public B (A instanceOfA) {
this.instanceOfA = instanceOfA;
}
public void methodThatUsesString () {
// Do stuff with the string
Log.d("I have the string", instanceOfA.commonString);
}
}
Or even use a getter or setter if performance is not an issue.
Many answers depending on how the string will be used.
If it's a constant string, one that will never change, never use final static String
public final static String AUTHOR_MAIL = "lala#gmail.com";
Then you can use it in a static way wherever you want.
email.addTo(MyClass.AUTHOR_MAIL);
If this String will be used in different Activities you can not access it directly (you can not tell if the other Activity is still alive). You have to use Persistence Mechanisms such as SharedPreferences or directly send needed data in your Intent.
If it's in a helper class inside your Activity, you can just use mObject.mail to get it.

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