Consider the following POJOs:
public class PersonVo {
private String firstName;
private String lastName;
}
private class PersonEntity {
private String fullName;
}
Using MapStruct, I want create mapper that PersonVo to PersonEntity.
I need mapping multiple source fields firstName, lastName to one target filed fullName.
Here is pseudo code what I want to.
[Want Solution A]
#Mapper
public interface PersonMapper {
#Mapping(target = "fullName", source = {"firstName", "lastName"}, qualifiedByName="toFullName")
PersonEntity toEntity(PersonVo person);
#Named("toFullName")
String translateToFullName(String firstName, String lastName) {
return firstName + lastName;
}
}
[Want Solution B]
#Mapper
public interface PersonMapper {
#Mapping(target = "fullName", source = PersonVo.class, qualifiedByName="toFullName")
PersonEntity toEntity(PersonVo person);
#Named("toFullName")
String translateToFullName(PersonVo pserson) {
return pserson.getFirstName() + pserson.getLastName();
}
}
Is there any way this can be achieved?
Here is my answer.
#Mapper
public interface PersonMapper {
#Mapping(target = "fullName", source = ".", qualifiedByName="toFullName")
PersonEntity toEntity(PersonVo person);
#Named("toFullName")
String translateToFullName(PersonVo pserson) {
return pserson.getFirstName() + pserson.getLastName();
}
}
Main point is that
#Mapping(target = "fullName", source = ".", qualifiedByName="toFullName")
It can make use source object by parameter.
First I would go with public abstract class for Mappers. Makes it easier to extend them and create inheritance between the generated code and the abstract class. But here is your solution:
You can achieve this by creating a #AfterMapping annotated method. So something like
#AfterMapping
default void concat(#MappingTarget PersonEntity person, PersonVo person) {
... manipulate the target value
}
MapStruct documentation
Related
I have the following case:
**public class SimpleSource {
private String name;
private String description;
// getters and setters
}
public class SimpleDestination {
private String name__c;
private String description__c;
// getters and setters
ContactMapper contactMapper = Mappers.getMapper(ContactMapper.class);
#Mapping(source = "name", target = "name__c")
#Mapping(source = "description", target = "description__c")
Target__c customerContact(Source source);**
How can I avoid adding this #Mapping for all fields and just said that target has suffix "__c" targetFieldName = sourceFieldName+suffix
MapStruct uses its AccessorNamingStrategy SPI to detect names of properties.
This means that in order to achieve what you are looking for you'll need to provide you own AccessorNamingStrategy.
You can read more about it in the MapStruct Documentation
I have a following class definition
[XmlRoot(ElementName = "person",Namespace = "MyNamespace")]
public class Person : IXmlSerializable
{
public string FirstName { get; set; }
[XmlNamespaceDeclarations]
public XmlSerializerNamespaces Namespaces
{
get
{
var xmlSerializerNamespaces = new XmlSerializerNamespaces();
xmlSerializerNamespaces.Add("My", "MyNamespace");
return xmlSerializerNamespaces;
}
}
public string LastName { get; set; }
public XmlSchema GetSchema()
{
return null;
}
/// <exception cref="NotSupportedException"/>
public void ReadXml(XmlReader reader)
{
throw new NotSupportedException();
}
public void WriteXml(XmlWriter writer)
{
writer.WriteElementString("firstName",FirstName);
writer.WriteElementString("lastName", LastName);
}
}
an I want to serialize it with My: prefix for MyNamespace, so when I call code
var xmlSerializer = new XmlSerializer(typeof(Person));
var person = new Person
{ FirstName = "John",LastName = "Doe"};
xmlSerializer.Serialize(Console.Out, person, person.Namespaces);
I expect following output:
<?xml version="1.0" encoding="ibm850"?>
<My:person xmlns:My="MyNamespace">
<My:firstName>John</My:firstName>
<My:lastName>Doe</My:lastName>
</My:person>
But instead of it I am getting following output:
<?xml version="1.0" encoding="ibm850"?>
<person xmlns="MyNamespace">
<firstName>John</firstName>
<lastName>Doe</lastName>
</person>
I know that writing prefixes works when I use SerializableAttribute attribute and not inherit from IXmlSerializable, but my class in the project is much more complex and I can't use default XmlSerializer.
The XmlSerializer type doesn't offer anything out-of-the-box to handle this.
If you really need to use XmlSerializer, you are going to end up with a custom XmlSerializer implementation, which isn't quite open to extend. For this reason the implementation below is more a proof of concept, just to give you an idea or a starting point.
For brevity I have omitted any error handling and only focussed on the Person class in your question. There's still some work to do to handle any nested complex properties.
As the Serialize methods are not virtual we'll have to shadow them. The main idea is to direct all overloads to a single one having the custom implementation.
Because of the customization, we'll have to be more explicit in the Person class when writing the xml elements for its properties by specifying the xml namespace to be applied.
The code below
PrefixedXmlSerializer xmlSerializer = new PrefixedXmlSerializer(typeof(Person));
Person person = new Person {
FirstName = "John",
LastName = "Doe"
};
xmlSerializer.Serialize(Console.Out, person, person.Namespaces);
results in
<My:person xmlns:My="MyNamespace">
<My:firstName>John</My:firstName>
<My:lastName>Doe</My:lastName>
</My:person>
It's up to you to consider whether this all is acceptable.
In the end, <My:person xmlns:My="MyNamespace"> equals <person xmlns="MyNamespace">.
Person
[XmlRoot(ElementName = "person", Namespace = NAMESPACE)]
public class Person : IXmlSerializable
{
private const string NAMESPACE = "MyNamespace";
public string FirstName { get; set; }
[XmlNamespaceDeclarations]
public XmlSerializerNamespaces Namespaces
{
get
{
var xmlSerializerNamespaces = new XmlSerializerNamespaces();
xmlSerializerNamespaces.Add("My", NAMESPACE);
return xmlSerializerNamespaces;
}
}
public string LastName { get; set; }
public XmlSchema GetSchema()
{
return null;
}
/// <exception cref="NotSupportedException"/>
public void ReadXml(XmlReader reader)
{
throw new NotSupportedException();
}
public void WriteXml(XmlWriter writer)
{
// Specify the xml namespace.
writer.WriteElementString("firstName", NAMESPACE, FirstName);
writer.WriteElementString("lastName", NAMESPACE, LastName);
}
}
PrefixedXmlSerializer
public class PrefixedXmlSerializer : XmlSerializer
{
XmlRootAttribute _xmlRootAttribute;
public PrefixedXmlSerializer(Type type) : base(type)
{
this._xmlRootAttribute = type.GetCustomAttribute<XmlRootAttribute>();
}
public new void Serialize(TextWriter textWriter, Object o, XmlSerializerNamespaces namespaces)
{
// Out-of-the-box implementation.
XmlTextWriter xmlTextWriter = new XmlTextWriter(textWriter);
xmlTextWriter.Formatting = Formatting.Indented;
xmlTextWriter.Indentation = 2;
// Call the shadowed version.
this.Serialize(xmlTextWriter, o, namespaces, null, null);
}
public new void Serialize(XmlWriter xmlWriter, Object o, XmlSerializerNamespaces namespaces, String encodingStyle, String id)
{
// Lookup the xml namespace and prefix to apply.
XmlQualifiedName[] xmlNamespaces = namespaces.ToArray();
XmlQualifiedName xmlRootNamespace =
xmlNamespaces
.Where(ns => ns.Namespace == this._xmlRootAttribute.Namespace)
.FirstOrDefault();
// Write the prefixed root element with its xml namespace declaration.
xmlWriter.WriteStartElement(xmlRootNamespace.Name, this._xmlRootAttribute.ElementName, xmlRootNamespace.Namespace);
// Write the xml namespaces; duplicates will be taken care of automatically.
foreach (XmlQualifiedName xmlNamespace in xmlNamespaces)
{
xmlWriter.WriteAttributeString("xmlns", xmlNamespace.Name , null, xmlNamespace.Namespace);
}
// Write the actual object xml.
((IXmlSerializable)o).WriteXml(xmlWriter);
xmlWriter.WriteEndElement();
}
}
Try the following.
public void WriteXml(XmlWriter writer)
{
writer.WriteAttributeString("xmlns", "my", null, "MyNamespace");
writer.WriteElementString("firstName", FirstName);
writer.WriteElementString("lastName", LastName);
}
Do you need to use XmlSerializer? If not, try following code:
Person.cs
Add new method:
public void Serialize(XmlWriter writer)
{
writer.WriteStartDocument();
writer.WriteStartElement("My", "Person", "MyNamespace");
writer.WriteElementString("My", "FirstName", "MyNamespace", FirstName);
writer.WriteElementString("My", "LastName", "MyNamespace", LastName);
writer.WriteEndElement();
writer.WriteEndDocument();
}
Usage
var person = new Person { FirstName = "John", LastName = "Doe" };
person.Serialize(new XmlTextWriter(Console.Out));
Let us take the following JSON response which I want to return from my REST service,
{
"id" : 123,
"name" : "ABC",
}
For the above JSON response, I can create a POJO class like,
public class Student{
private long id;
private String name;
//getters and setters
}
So, I can write a GET service to return the Student object which will be then transformed as JSON.
#GET
#Produces(MediaType.APPLICATION_JSON)
public Response get(){
Student student = new Student();
student.setId(123);
student.setName("ABC");
return Response.ok(student).build();
}
It works fine. Now I want to introduce optional parameters to my JSON response as follows,
{
"id" : 123,
"name" : "ABC",
"params" : {"param1":"xxx","param2":342}
}
Here the params in the JSON response is an Object type and the attributes of that object are not fixed. It will vary for every request like sometime it can have 3 attributes and sometime it will have none. I don't know how to create my POJO class for this requirement. Can anybody suggest me a way how to do it?
Unless you don't need anything special, you should design it as like:
public class Student{
private long id;
private String name;
//getters and setters
private Map<String, String> parameters = new HashMap<>();
public void add(String key, String value) {
parameters.put(key, value);
}
public void addAll(Map<String, String> map) {
parameters.putAll(map);
}
}
If you need type safety then the design is little bit complicated a consider using something like:
class StudentParameters {
long param1;
String param2;
}
and Student:
public class Student{
private long id;
private String name;
//getters and setters
private StudentParameters studentParameters;
public setStudentParameters(final StudentParameters studentParameters) {
this.studentParameters = studentParameters;
}
}
Do not create complex hierarchies e.g Map<List<List>, List<List>> it will complicate whole structure.
I'm using EclipseLink to run some Native SQL. I need to return the data into a POJO. I followed the instructions at EclipseLink Docs, but I receive the error Missing descriptor for [Class]
The query columns have been named to match the member variables of the POJO. Do I need to do some additional mapping?
POJO:
public class AnnouncementRecipientsFlattenedDTO {
private BigDecimal announcementId;
private String recipientAddress;
private String type;
public AnnouncementRecipientsFlattenedDTO() {
super();
}
public AnnouncementRecipientsFlattenedDTO(BigDecimal announcementId, String recipientAddress, String type) {
super();
this.announcementId = announcementId;
this.recipientAddress = recipientAddress;
this.type = type;
}
... Getters/Setters
Entity Manager call:
public List<AnnouncementRecipientsFlattenedDTO> getNormalizedRecipientsForAnnouncement(int announcementId) {
Query query = em.createNamedQuery(AnnouncementDeliveryLog.FIND_NORMALIZED_RECIPIENTS_FOR_ANNOUNCEMENT, AnnouncementRecipientsFlattenedDTO.class);
query.setParameter(1, announcementId);
return query.getResultList();
}
I found out you can put the results of a Native Query execution into a List of Arrays that hold Objects. Then one can iterate over the list and Array elements and build the desired Entity objects.
List<Object[]> rawResultList;
Query query =
em.createNamedQuery(AnnouncementDeliveryLog.FIND_NORMALIZED_RECIPIENTS_FOR_ANNOUNCEMENT);
rawResultList = query.getResultList();
for (Object[] resultElement : rawResultList) {
AnnouncementDeliveryLog adl = new AnnouncementDeliveryLog(getAnnouncementById(announcementId), (String)resultElement[1], (String)resultElement[2], "TO_SEND");
persistAnnouncementDeliveryLog(adl);
}
You can only use native SQL queries with a class if the class is mapped. You need to define the AnnouncementRecipientsFlattenedDTO class as an #Entity.
Otherwise just create the native query with only the SQL and get an array of the data back and construct your DTO yourself using the data.
Old question but may be following solution will help someone else.
Suppose you want to return a list of columns, data type and data length for a given table in Oracle. I have written below a native sample query for this:
private static final String TABLE_COLUMNS = "select utc.COLUMN_NAME, utc.DATA_TYPE, utc.DATA_LENGTH "
+ "from user_tab_columns utc "
+ "where utc.table_name = ? "
+ "order by utc.column_name asc";
Now the requirement is to construct a list of POJO from the result of above query.
Define TableColumn entity class as below:
#Entity
public class TableColumn implements Serializable {
#Id
#Column(name = "COLUMN_NAME")
private String columnName;
#Column(name = "DATA_TYPE")
private String dataType;
#Column(name = "DATA_LENGTH")
private int dataLength;
public String getColumnName() {
return columnName;
}
public void setColumnName(String columnName) {
this.columnName = columnName;
}
public String getDataType() {
return dataType;
}
public void setDataType(String dataType) {
this.dataType = dataType;
}
public int getDataLength() {
return dataLength;
}
public void setDataLength(int dataLength) {
this.dataLength = dataLength;
}
public TableColumn(String columnName, String dataType, int dataLength) {
this.columnName = columnName;
this.dataType = dataType;
this.dataLength = dataLength;
}
public TableColumn(String columnName) {
this.columnName = columnName;
}
public TableColumn() {
}
#Override
public int hashCode() {
int hash = 0;
hash += (columnName != null ? columnName.hashCode() : 0);
return hash;
}
#Override
public boolean equals(Object object) {
if (!(object instanceof TableColumn)) {
return false;
}
TableColumn other = (TableColumn) object;
if ((this.columnName == null && other.columnName != null) || (this.columnName != null && !this.columnName.equals(other.columnName))) {
return false;
}
return true;
}
#Override
public String toString() {
return getColumnName();
}
}
Now we are ready to construct a list of POJO. Use the sample code below to construct get your result as List of POJOs.
public List<TableColumn> findTableColumns(String table) {
List<TableColumn> listTables = new ArrayList<>();
EntityManager em = emf.createEntityManager();
Query q = em.createNativeQuery(TABLE_COLUMNS, TableColumn.class).setParameter(1, table);
listTables = q.getResultList();
em.close();
return listTables;
}
Also, don't forget to add in your POJO class in persistence.xml! It can be easy to overlook if you are used to your IDE managing that file for you.
Had the same kind of problem where I wanted to return a List of POJOs, and really just POJOs (call it DTO if you want) and not #Entity annotated Objects.
class PojoExample {
String name;
#Enumerated(EnumType.STRING)
SomeEnum type;
public PojoExample(String name, SomeEnum type) {
this.name = name;
this.type = type;
}
}
With the following Query:
String query = "SELECT b.name, a.newtype as type FROM tablea a, tableb b where a.tableb_id = b_id";
Query query = getEntityManager().createNativeQuery(query, "PojoExample");
#SuppressWarnings("unchecked")
List<PojoExample> data = query.getResultList();
Creates the PojoExample from the database without the need for an Entity annotation on PojoExample. You can find the method call in the Oracle Docs here.
edit:
As it turns out you have to use #SqlResultSetMapping for this to work, otherwise your query.getResultList() returns a List of Object.
#SqlResultSetMapping(name = "PojoExample",
classes = #ConstructorResult(columns = {
#ColumnResult(name = "name", type = String.class),
#ColumnResult(name = "type", type = String.class)
},
targetClass = PojoExample.class)
)
Just put this anywhere under your #Entity annotation (so in this example either in tablea or tableb because PojoExample has no #Entity annotation)
I have a model called 'UserRoleHolder' like below.
#Entity
public class UserRoleHolder extends Model implements RoleHolder {
private static final long serialVersionUID = 1L;
#EmbeddedId
public UserRoleHolderPK userRoleHolderPK;
public List<UserPermission> permissions;
public List<UserRole> roles;
....
I made a composite PK called UserRoleHolderPK and it contains two foreign keys like below.
#Embeddable
public class UserRoleHolderPK {
#Basic
public Long userId;
#Basic
public Long projectId;
public UserRoleHolderPK(Long userId, Long projectId) {
this.userId = userId;
this.projectId = projectId;
}
public boolean equals(Object object) {
if (object instanceof UserRoleHolderPK) {
UserRoleHolderPK userRoleHolderPK = (UserRoleHolderPK) object;
return userId == userRoleHolderPK.userId && projectId == userRoleHolderPK.projectId;
} else {
return false;
}
}
public int hashCode() {
return (int) (userId + projectId);
}
}
userId and projectId are from other Models. (User.java and Project.java)
Then, in 'UserRoleHolder' class, I made a method called 'findRolesById' like below.
public static List<? extends Role> findRolesById(Long userId, Long projectId) {
return find
.where()
.eq("userRoleHolderPK", new UserRoleHolderPK(userId, projectId))
.findUnique().roles;
}
However, when I tried to run a test code like below, I encountered serious errors.
#Test
public void findRolesById() {
// Given
// When
#SuppressWarnings("unchecked")
List<UserRole> list = (List<UserRole>) UserRoleHolder.findRolesById(1l, 1l);
// Then
assertThat(list.get(0).name).isEqualTo("manager");
}
Errors are like,
'Syntax error in SQL statement "SELECT T0.USER_ID C0, T0.PROJECT_ID C1 FROM USER_ROLE_HOLDER T0 WHERE T0.NULL[*] = ? "; expected "identifier"; SQL statement: select t0.user_id c0, t0.project_id c1 from user_role_holder t0 where t0.null = ? [42001-158]
Bind values:[null]
Query was:
select t0.user_id c0, t0.project_id c1 from user_role_holder t0 where t0.null = ?
I think I missed some serious and basic stuff when I used JPA. Please, let me know what is the problem.
I think your problem is that you are trying to compare the Embeddedid object and not its fields, I don't think that the program will be smart enough as to know how to convert an user object comparison (the equals) to sql, so you might want to try something like this:
public static List<? extends Role> findRolesById(Long userId, Long projectId) {
return find
.where()
.eq("userRoleHolderPK.userId", userId)
.eq("userRoleHolderPK.projectId", projectId)
.findUnique().roles;
}