My entity class:
class User : ActiveRecord<User>() {
var name by Column(String.javaClass);
var id by Column(Int.javaClass);
}
now I want to set name value by refelection:
var clazz = User().javaClass
var record = clazz.newInstance()
var field = record.getDeclaredField(it + "$" + "delegate")
field.set(record, "aa")
then error:
entity.Column field ActiveRecord4k.User.name$delegate to java.lang.String
how to do this?
If you want to reflectively set the property as if it was record.name = "...", then you can use kotlin-reflect, the Kotlin reflection API (see the reference).
With kotlin-reflect, setting a property value is done like this:
val property = outputs::class.memberProperties.find { it.name == "name" }
if (property is KMutableProperty<*>) {
property.setter.call(record, "value")
}
If the property is delegated, the call will be dispatched to the delegate.
Or, you can do that with Java reflection, finding the setter for your property first:
var setter = clazz.getDeclaredMethod("set" + it.capitalize())
setter.invoke(record, "aa")
But there is no way, at least at this point, to overwrite the delegate instance of that property, because the field storing it, name$delegate, is final.
Related
it works fine if i change lateinit var id: String in the Payment.kt and CartPayment.kt to var id: String? = "", but the problem is i want the id to be required, how can i achieve that ?
The Error:
java.lang.RuntimeException: Unable to create application: io.realm.exceptions.RealmMigrationNeededException: Migration is required due to the following errors:
- Property 'CartPayment.id' has been made required.
- Property 'Payment.id' has been made required.
Model :
open class Payment() : RealmObject() {
#PrimaryKey
lateinit var id: String
var typeValue: Int = 0
var statusValue: Int = 0
var value: Double = 0.0
var referenceNumber: String? = null
Note: Payment and CartPayment models are identical except for the class name
Migration.kt
class Migration : RealmMigration {
override fun migrate(realm: DynamicRealm, oldVersion: Long, newVersion: Long) {
var oldVersion = oldVersion
val schema = realm.schema
if (oldVersion == 0L) {
schema.create("Payment")
.addField("id", String::class.java, FieldAttribute.PRIMARY_KEY)
.addField("typeValue", Int::class.java)
.addField("statusValue", Int::class.java)
.addField("value", Double::class.java)
.addField("referenceNumber", String::class.java)
schema.get("Order")!!
.addRealmListField("payments", schema.get("Payment")!!)
oldVersion++
}
if (oldVersion == 1L) {
schema.create("CartPayment")
.addField("id", String::class.java, FieldAttribute.PRIMARY_KEY)
.addField("typeValue", Int::class.java)
.addField("statusValue", Int::class.java)
.addField("value", Double::class.java)
.addField("referenceNumber", String::class.java)
schema.get("Order")!!
.addField("cashPaymentAmount", Float::class.java)
.addField("change", Float::class.java)
oldVersion++
}
}
}
App.kt
class App: Application() {
override fun onCreate() {
super.onCreate()
Realm.init(this)
val realmConfig = RealmConfiguration.Builder()
.schemaVersion(2)
.migration(Migration())
.build()
Realm.getInstance(realmConfig)
Realm.setDefaultConfiguration(realmConfig)
Fresco.initialize(this)
}
}
.addField("id", String::class.java, FieldAttribute.PRIMARY_KEY, FieldAttribute.REQUIRED)
did the trick.
if you declare the variable to be lateinit, make sure to add FieldAttribute.REQUIRED.
Basically you are adding a new field "id" which is primary key (hence required key).
If you do not specify any value while initialisation (lateinit), how will realm migrate all the earlier records, which doesn't have an id, but is required after migration ? Hence the error.
Below solutions might work
Either pre-populate the id's (without using lateinit)
Transform your earlier records to have id's if they don't have
Check the official examples here
For me, it happened after I have done the Migration.
I have made a non-nullable object in Kotlin and on migration I was creating a nullable wrapper type like Double, Int, etc.
Just use
Double::class.java
instead of
Double::class.javaObjectType
How to transform a List into a new List by excluding a property in T.
For instance if User data class has 10 properties, I need to transform List into a new List without one particular property in User . New List like List
data class User(val name: String, val age: Int)
var userList = mutableListOf<User>()
var nameList= userList.map { it.name }
If a List to be created without property 'age'. Like
var withoutAgeList
In your first example:
var userList = mutableListOf<User>()
var nameList= userList.map { it.name }
The question "What's the type of nameList?" has a simple answer: List<String>. So let me ask you a similar question: What's the type of withoutAgeList? The answer to that question informs the answer to your question.
Perhaps a user without the age property is a separate AgelessUser class, meaning withoutAgeList is of type List<AgelessUser>. In that case, I suggest either a constructor or a factory function that builds AgelessUser from User, and you want one of these:
val withoutAgeList = userList.map { AgelessUser(it) } // constructor
val withoutAgeList = userList.map { agelessUserOf(it) } // factory
Alternatively, maybe the age property in User is nullable and immutable, and you want to represent users without an age as a regular User where age=null. In this case, you could copy the Users and override the age field
// TODO: pass all the other fields too
val withoutAgeList = userList.map { User(it.name, null) }
Assuming Users is a data class, we can avoid explicitly naming all fields by making use of copy():
val withoutAgeList = userList.map { it.copy(age = null) }
Maybe the age property is nullable and mutable — and you actually want to change the users in place instead of copying them. This is somewhat risky and I don't advocate doing it this way unless you really know what you're doing though.
userList.forEach { it.age = null }
// They're actually the same list!
val withoutAgeList = userList
In such a simple case you can map a list of Users into a list of strings:
val names: List<String> = userList.map(User::name)
Or you can declare a DTO and map into the latter:
class UserWithoutAge(val name: String)
val usersWithoutAge: List<UserWithoutAge> = userList.map { UserWithoutAge(it.name) }
P.S. you don't have to write an explicit type
You can use the Object Oriented approach:
data class User(val name: String, val age: Int)
data class UserNoAge(var name: String) {
constructor(user: User) : this(user.name)
}
var userList = listOf(User("John", 25), User("Jane", 30))
var userNoAge: List<UserNoAge> = mutableListOf<UserNoAge>()
userNoAge = userList.map{ UserNoAge(it) }
println(userNoAge) // [UserNoAge(name=John), UserNoAge(name=Jane)]
I'm using TornadoFX 1.7.5 and I can't seem to get bound properties to work. I have the below ItemViewModels
class DynamicMenuViewModel : ItemViewModel<DynamicMenu>(DynamicMenu()) {
val title = bind { item?.title?.toProperty() }
val isBold = bind { item?.isBold?.toProperty() }
val routes = bind { item?.routes?.toProperty() }
}
data class DynamicMenu(var title: String = "", var isBold: Boolean = false, var routes: MutableList<MenuRouteViewModel> = mutableListOf())
class MenuRouteViewModel : ItemViewModel<MenuRoute>(MenuRoute()) {
val url = bind { item?.url?.toProperty() }
val title = bind { item?.title?.toProperty() }
val isBold = bind { item?.isBold?.toProperty() }
val showNew = bind { item?.showNew?.toProperty() }
}
data class MenuRoute(var url: String = "", var title: String = "", var showNew: Boolean = false, var isBold: Boolean = false)
Which are bound like this:
//routesController.dynamicMenu is an instance of DynamicMenuViewModel()
textfield(property = routesController.dynamicMenu.title) {
prefWidth = formWidth * .5
gridpaneConstraints {
columnRowIndex(0, 1)
marginLeft = 10.0
columnSpan = 2
marginBottom = 20.0
}
}
checkbox(property = routesController.dynamicMenu.isBold){
gridpaneConstraints {
columnRowIndex(2, 1)
marginLeft = 15.0
marginBottom = 20.0
}
}
Then the following functions commit the models and prints them to the screen when I click a button:
fun onClick(){
commitModel()
println(dynamicMenu.item.toString())
dynamicMenu.item.routes.forEach {
println(it.item.toString())
}
}
fun commitModel(){
dynamicMenu.item.routes.forEach {
it.commit()
}
dynamicMenu.commit()
}
The problem is that when I run the program and edit the textfields and checkboxes then click the button that runs onClick(), the backing item doesn't seem to be getting updated. So none of the updated values are printed to the console.
What am I doing wrong here?
The ViewModel can as you probably know only bind bidirectionally against JavaFX Properties. Your domain objects doesn't contain JavaFX properties, so you need to convert them. However, the toProperty() function you are using only operates on a value, and turns it into a Property. This property has no way of knowing about it's field owner, and hence cannot write back into the domain object.
Luckily, you can use the observable function to make your domain object properties writable as well:
val url = bind { item?.observable(MenuRoute::url) }
Since the observable function operates on a specific instance of a MenuRoute object, it now has enough information to write back into that instance when you commit() the model.
If you would consider changing the properties in your domain objects to be observable, you could write:
val url = bind(MenuRoute::url)
You can use the TornadoFX IDEA plugin inspection "Convert all properties to TornadoFX Properties" to automatically rework your properties. This would transform your MenuRoute object into:
class MenuRoute {
val isBoldProperty = SimpleBooleanProperty(false)
var isBold by isBoldProperty
val showNewProperty = SimpleBooleanProperty(false)
var showNew by showNewProperty
val urlProperty = SimpleStringProperty("")
var url by urlProperty
val titleProperty = SimpleStringProperty("")
var title by titleProperty
}
(You have to manually remove the data modifier on your class. Also beware that the current version of the plugin has a bug in the conversion function that would leave the old parameters - a new version will be released shortly).
If you don't want to do that for various reasons, I was just able to support that nice syntax even for mutable vars like you have, so from TornadoFX 1.7.6 you can use this syntax in your binding statements even if you don't want to change your data classes:
val url = bind(MenuRoute::url)
Class Carro {
String name
String marca
String matricula
}
Class CarroMovel{
String pro1
String prop2
String prop3
Carro carro
static hasMany = [ carros: Carro]
}
def save2 = {
def carroInstance = new Carro()
def carroMovelInstance = new CarroMovel()
carroInstance.name = params.name
carroInstance.marca = params.marca
carroInstance.matricula = params.matricula
carroMovelInstance.prop1 = params.carroMovel.prop1
carroMovelInstance.prop2 = params.carroMovel.prop2
carroMovelInstance.prop3 = params.carroMovel.prop3
carroInstance.save()
carroMovelInstance.carro = carroInstance
carroMovelInstance.save()
}
The CarroInstance is saving, but the carroMovelInstance isn't. I cannot figure it out. Any help would be apreciated.
Grooveek is correct in that you haven't ever invoked carroMovelInstance.save().
However, it might be simpler for you to simply take advantage of Grails' databinding, instead of unnecessarily creating the associations and manually binding the parameters.
// Update your Carro domain.
def Carro {
String name
String marca
String matricula
// will cause persistence operations to cascade from CarroMovel to Carro
static belongsTo = CarroMovel
}
// Update your save2 action.
// By passing 'params' to the CarroMovel constructor, Grails will bind request
// parameters to domain properties of the same name; it even works with associations!
def save2 = {
def carroMovelInstance = new CarroMovel(params)
if(carroMovelInstance.validate) {
carroMovelInstance.save()
}
}
Read up on Grails Data Binding, particularly the parts about associations. Additionally, read "Understanding Cascading Updates and Deletes" to understand how a call to save() on a parent domain object will (or will not) cascade to an associated domain object.
you never ask for the carroMovelInstance to save... The carro instance has nor reference to carroMovel instance so there is no cascading of saving
If I have an entity with a collection property for another entity. What is the best way to add a new entity and it's related entities? The problem I have is that the collection is initially null.
var form = new Form()
{
Name = "TestForm"
};
ctx.Forms.Add(form);
var formField = new FormField()
{
Name = "TestField"
};
form.FormFields.Add(formField);
ctx.SaveChanges();
The form.FormFields property above is null so I get an exception. I know I could set the relationship in the other direction but I haven't defined a Form property on FormFields (and I don't really want to).
So what is the cleanest solution to for this?
The simplest solution is to initialize the collection like this:
var form = new Form() {
Name = "TestForm"
};
ctx.Forms.Add(form);
var formField = new FormField() {
Name = "TestField"
};
if(form.FormFields == null)
form.FormFields = new List<FormField>();
form.FormFields.Add(formField);
ctx.SaveChanges();