I’ve got an application with Hibernate (JPA) which I am using in combination with Jinq. I’ve got a table which lists entities and I want the user to be able to filter it. In the table there are persons listed.
#Entity
public class Person {
private String firstName;
private String surName;
#Id
private int id;
public Person() {
}
public Person(final String pFirstName, final String pSurName, final int pID) {
firstName = pFirstName;
surName = pSurName;
id = pID;
}
public int getId() {
return id;
}
public void setId(final int pID) {
id = pID;
}
public String getFirstName() {
return firstName;
}
public void setFirstName(final String pFirstName) {
return firstName = pFirstName;
}
public String getSurName() {
return surName;
}
public void setSurName(final String pSurName) {
surName = pSurName;
}
}
I am using JavaFX for this, but this shouldn’t matter. First thing I tried was to filter the persons by their surname. For filtering, I used Jinq in combination with lambda. My filtering code looks like this:
private List<Person> getFilteredPersons(final String pSurName){
JPAJinqStream<Person> stream = streamProvider.streamAll(Person.class);
stream.where(person -> person.getSurName().contains(pSurName));
List<Person> filteredList = stream.toList();
stream.close();
return filteredList;
}
So the object I am operating on is a normal String. I don’t think that my Person class has anything to do with that. My first thought was, that you can’t use the method boolean contains(...) in lambda because when the error showed up, it said:
Caused by: java.lang.IllegalArgumentException: Could not analyze lambda code
So my question is, is it somehow possible to use the contains-method of a String in lambdacode?
Your question has nothing to do with JPA or lambdas, but everything to do with jinq: it simply doesn't support translating String.contains() to a database query. See http://www.jinq.org/docs/queries.html#N65890 for what is supported.
Related
I have a class Person in gwt and I have sent an instance of Person with servlet converted using Gson from server to client. But in the client side seems I can't use Gson. From what I read in forums it seems that the best way is using AutoBeans to convert Json to object Person again.
However in AutoBeans I can only use an interface. I will appreciate if anyone can help me write it.
A json example I get from server and want to convert to Person class again:
{"name":"aaa","family":"fff","username":"uuu","age":20,"phones":[{"id":0,"phoneNumber":"0911111"}],"relatives":[null]}
public class Person implements Serializable {
private String name;
private String family;
private String username;
private int age;
private List<Phone> phones;
private List<Person> relatives;
public Person() {
}
public Person(String name, String family, String username, int age, List<Phone> phones, List<Person> relatives) {
this.name = name;
this.family = family;
this.username = username;
this.age = age;
this.phones = phones;
this.relatives = new ArrayList<Person>();
this.relatives = relatives;
}
public void addPhone(Phone p) {
phones.add(p);
}
public String getName() {
return this.name;
}
public String getFamily() {
return this.family;
}
public int getAge() {
return this.age;
}
public String getUsername() {
return this.username;
}
public List<Phone> getNumbers() {
return this.phones;
}
public List<Person> getRelatives() {
return this.relatives;
}
public String getAllNumbers() {
return Phone.convertPhonesToText(phones);
}
public static Person findPerson(List<Person> personList, String username) {
// .....
}
public static List<Person> convertTextToPersons(List<Person> personList, String personsText) {
// .....
}
public String convertPersonsToText() {
// ....
}
}
Yep, as commented by Tobika the other answer indicates that AutoBeans requires an Interface. AutoBeans feets better if you use it on both sides, client and server side and you define all your models as interfaces.
If you want to use your class models, you can use GWT Jackson which is pretty similar to AutoBeans but it uses your models, binding the json to your model (like other server side libraries; jackson, gson, etc):
https://github.com/nmorel/gwt-jackson
public static interface PersonMapper extends ObjectMapper<Person> {}
#Override public void onModuleLoad() {
PersonMapper mapper = GWT.create(PersonMapper.class);
String json = mapper.write(new Person("John", "Doe"));
GWT.log( json ); // > {"firstName":"John","lastName":"Doe"}
Person person = mapper.read(json);
GWT.log(person.getFirstName() + " " + person.getLastName());
}
Alternatively, you can use just plain GWT with JsInterop. This has many limitations but even with this limitation, it is a pretty good option. This is my favorite option if you can avoid inheritance in your DTOs. But this has the big advantage of being super lightweight (actually zero overhead mapping overhead and zero code overhead as it uses native parsing and no copies, accesing directly to the parsed json object). Limitations: cannot use inheritance, "broken type system" (all X instanceof SomeDtoType returns always true as all DTOs are of type Object wich makes sense because we are actually using the parsed JSON), cannot use collections only native arrays (but thanks to java8 Stream this should not be a problem, whatever you want to do with start with Stream.of(arr)), and only Double and Boolean boxed types supported (not supported any fancy type like Date or BigInteger, not supported long/Long...).
#JsType(isNative=true, package=GLOBAL, name="Object") final class Person {
// you can use getter/setter but as this class is final DTO adds no value
public String firstName; public String lastName; public Phome[] numbers;
// you can add some helper methods, don't forget to skip serialization!
public final #JsOverlay #JsonIgnore List<Phone> getNumberList() {
return Stream.of(numbers).collect(Collectors.toList());
}
}
#JsType(isNative=true, package=GLOBAL, name="Object) final class Phone {
public String number;
}
#JsMethod(namespace = "JSON") public static native <T> T parse(String text);
#Override public void onModuleLoad() {
Person person = parse("{\"firstName\":\"John\",\"lastName\":\"Doe\"}");
GWT.log(person.firstName + " " + person.lastName);
}
These simple and limited DTOs are more a DTO scheme than a type. But has a big advantage, this DTOs works out of the box with most of the server side parsers. Jackson and GSON will encode and parse without any configuration.
How do you save a JSON Array as an item attribute? AWS documentation is the absolute worst thing ever - it contradicts itself, a lot of things are either redundant or only partially explained, some things aren't explained at all - I don't know how anyone manages to use it.
Anyway, suppose I have a table called Paths, and a path has a name, an ID, and a list of LatLngs (formatted as a JSON Array)
In the class definition for this table, I have
#DynamoDBTable(tableName = "Paths")
public class Path {
private String id;
private String name;
private JSONArray outlineJSON;
with getters and setters like
#DynamoDBRangeKey(attributeName = "name")
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
which works fine for strings, booleans and numbers, and the object saves successfully to the table.
AWS documentation mentions JSON several times, and says it can handle lists, but it doesn't explain how to use lists or give any examples.
I used #DynamoDBHashKey for the id, #DynamoDBRangeKey for name, and #DynamoDBAttribute for other strings, numbers or booleans, and I tried it here
#DynamoDBAttribute(attributeName = "outline")
private JSONArray getOutlineJSON() {
return outlineJSON;
}
private void setOutlineJSON(JSONArray outlineJSON) {
this.outlineJSON = outlineJSON;
}
It successfully saved the object but without the array.
How do I save the array? I can't find an explanation anywhere. I think #DynamoDBDocument might have something to do with it, but all the documentation on the subject gives unrelated examples, and I can't find any using a list like my in situation.
EDIT: For now, I have a working solution - I can easily convert my lists to JSONArrays and then convert those to Strings, and vice-versa.
You can define your class to be something like
#DynamoDBTable(tableName = "Paths")
public class Path {
private String id;
private String name;
private LatLang latLangs;
#DynamoDBHashKey(attributeName="id")
public String getId() { return id;}
public void setId(String id) {this.id = id;}
#DynamoDBRangeKey(attributeName = "name")
public String getName() { return name; }
public void setName(String name) { this.name = name; }
#DynamoDBDocument
public static class LatLang{
public String lat;
public String lang;
}
}
I created a table in AWS DynamoDB which I'll be using for a basic questions and answers forum I'm developing and after table creation and some successful tests where I was able to insert data I decided to add an attribute for storing date of question, which I called time_stamp but for an unknown reason for me I'm not being able to refresh table structure, I mean, data is still saved with no errors but with no time_stamp field.
I tried deleting the table and recreating several times and modifying time_stamp data type with no success so I'm lost and I hope anyone can help me. I thought the only neccesary thing to alter table structure in DynamoDB is just modifing the mapping class in Java but cannot make it to work.
My mapping class is the next:
import com.amazonaws.mobileconnectors.dynamodbv2.dynamodbmapper.*;
#DynamoDBTable(tableName = "community_questions")
public class CommunityQuestion {
private long question_id;
private String time_stamp;
private String user_id;
private String subject;
private String question;
#DynamoDBHashKey(attributeName = "question_id")
public long getQuestionId() { return question_id; }
public void setQuestionId(long questionId) { this.question_id = questionId; }
#DynamoDBAttribute (attributeName = "time_stamp")
public String geTimeStamp() {
return time_stamp;
}
public void setTimeStamp(String timeStamp) {
this.time_stamp = timeStamp;
}
#DynamoDBAttribute (attributeName = "user_id")
public String getUserId() {
return user_id;
}
public void setUserId(String userId) {
this.user_id = userId;
}
#DynamoDBAttribute(attributeName = "subject")
public String getSubject() {
return subject;
}
public void setSubject(String subject) {
this.subject = subject;
}
#DynamoDBAttribute(attributeName = "question")
public String getQuestion() {
return question;
}
public void setQuestion(String question) {
this.question = question;
}
}
All data is being saved with no errors but time_stamp won't!!
I'm using mapper.save for saving operations.
Maybe anything I should refresh in AWS console?? Can't find anything.
Please help, and many thanks in advance.
There is a typo in your code. Rename geTimeStamp to getTimeStamp
DynamoDbMapper considers only methods with exactly "get" or "is" prefixes, and then checks for annotations on those in a second step. Its not picking up your added property because of that.
/**
* Returns whether the method given is a getter method we should serialize /
* deserialize to the service. The method must begin with "get" or "is",
* have no arguments, belong to a class that declares its table, and not be
* marked ignored.
*/
private static boolean isRelevantGetter(Method m) {
(soure)
I'm developing a service using apache thrift. I have a service named getUser which returns User object. I couldn't find any way to define user-defined data type as a return type for my service defined in .thrift file.
user.thrift file looks like:
service UserService
{
User getUser(1:i32 userId),
}
When I am compiling the user.thrift to generate java source code, I am getting "Type "User" has not been defined" error. Can anyone please help me, how to represent this user-defined java object as a data type in thrift.
The getUser method code in service implementation class:
#Override
public User getUser(int user id) throws TException {
// here is the code that fetch the user object from database
return user;
}
This is my User class, whose object is being returned by service getUser:
public class User {
private int userId;
private String name;
private String city;
private String country;
public int getUserId() {
return userId;
}
public void setUserId(int userId) {
this.userId = userId;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getCity() {
return city;
}
public void setCity(String city) {
this.city = city;
}
public String getCountry() {
return country;
}
public void setCountry(String country) {
this.country = country;
}
}
The relevant IDL could look like this:
struct User {
1 : i32 userId
2 : string name
3 : string city
4 : string country
}
So that's pretty straightforward. With that, you have two options:
use the Thrift-generated class as the data object, replacing your existing class
write some code that converts the data back and forth.
Both options have their pros and cons. With the first approach, you will lose the getter-only for the Id, because the field must be read/writable. But you don't have to convert any data.
The second approach leaves you with the getter/setter structure you have right now, with some minor modifications (the factory pattern could be worth a look). You pay that with the burden of additional data conversion from Thrift into your class and back.
It depends on the exact requirements, which option is the better one for your case.
Well i want to know if there is a much appropriate way to tackle generating auto id with string values, my first idea is creating an auto increment id which we can call auto_id then before saving a new entity I'll query for the latest data inside the db to get the id then I'll add 1 to my auto generate value column that I assign name which is stringValue+(id+1) though I'm concerned on how it will affect the performance as to saving this entity needs two access in db which is fetching and saving... like my question earlier is there a much appropriate way to handle this scenario?
And also sorry for my English guys if you want to clarify things with my question kindly ask, thnx in advance..
Here's my code for AttributeModel for hibernate annotation
#Component
#Entity
#Table(name="attribute_info")
public class AttributeModel {
#Id
#GeneratedValue(strategy=GenerationType.AUTO)
#Column(name="attr_id", nullable=false, unique=true)
private int id;
#Column(name="attr_name")
private String name;
#Column(name="attr_desc")
private String desc;
#Column(name="attr_active")
private int active;
#Column(name="attr_abbr")
private String abbr;
#OneToOne(cascade = CascadeType.ALL, fetch = FetchType.EAGER)
#JoinColumn(name="stats_id", referencedColumnName="stats_id")
private BaseStatisticModel baseStats;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getDesc() {
return desc;
}
public void setDesc(String desc) {
this.desc = desc;
}
public int getActive() {
return active;
}
public void setActive(int active) {
this.active = active;
}
public String getAbbr() {
return abbr;
}
public void setAbbr(String abbr) {
this.abbr = abbr;
}
public BaseStatisticModel getBaseStats() {
return baseStats;
}
public void setBaseStats(BaseStatisticModel baseStats) {
this.baseStats = baseStats;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
}
I can only say "Don't do it". How is a String ID like "str10001" better than 10001? It can't be an optimization as strings take more memory and more time. So I guess you need to pass it to some String-expecting method later.
If so, then pass "str" + id instead. Constructing the string on the fly surely won't saturate your server.
If not, then let us know what you actually need rather than what you think it could help you to achieve it.
I'm pretty sure, Hibernate can't do it. It couldn't some long time ago I checked it recently and it makes no sense (in any case, it's not a feature crowds would request).