Is there a simple way to add encrypted field functionality to JetBrains Exposed database framework for Kotlin?
https://github.com/JetBrains/Exposed
Derive a SecureVarchar column type from VarCharColumnType and use this type in the table.
class SecureVarCharColumnType(val l: Int = 255, c: String? = null) : VarCharColumnType(l, c) {
override fun valueToDB(value: Any?): Any? = value?.let {
return notNullValueToDB(Crypto.encrypt(it.toString()));
}
override fun valueFromDB(value: Any): Any {
return Crypto.decrypt(value.toString())
}
}
object Users : IntIdTable("user") {
val email = super.registerColumn<String>("email", SecureVarCharColumnType(255))
}
Related
im working with firebase for a couple months and so far i had no issues until now. im using kotlin and my problem is simple but i cant find a way out. i storage strings in database: path"/user/friends" , but i cant change the variable name and the strings were overwriting itselves. My solution was use "push()" until the "setValue()", but with this i have the following firebase structure:
"users": {
"yvrYpjMwVSPBvMAvDGo26hPlWWQ2": {
"email": "vinibarros.sp#gmail.com",
"friends": {
"-LfD9z6ke7FXFjxUb4td": {
"email": "teste#gmail.com"
},
"-LfDA-NaAYAMoWiPhXy4": {
"email": "teste2#gmail.com"
}
},
"primeiroLogin": true,
"stars": 0,
"tutorialComplete": false,
"uid": "yvrYpjMwVSPBvMAvDGo26hPlWWQ2",
"username": "Vinicius Barros"
}
}
basically hashmaps inside a hashmap ps:lol mindblow
how do i get the pushcode.value into an arraylist?
i have a class user that have the friend variable, until now this variable was typed as hashMap. and the call to get the email was "user.friends.value"
this worked because was one friend....
com.google.firebase.database.DatabaseException: Failed to convert value of type java.util.HashMap to String
When I added more than one user I got this error that references my class user, where have a "hashMap". But the firebase gives me another hashmap instead of string. I was thinking about: hashMap<hashMap<String,String>, null>.
i 've tried this:
class friends:
#Parcelize
class Friend(val hashMap: HashMap < String, String > ? ): Parcelable {
constructor(): this(null)
}
The activity where i show the friends:
val ref2 = FirebaseDatabase.getInstance().getReference("/users/" + cUid + "/friends/")
ref2.addListenerForSingleValueEvent(object: ValueEventListener {
override fun onCancelled(p0: DatabaseError) {
}
override fun onDataChange(p0: DataSnapshot) {
p0.children.forEach {
val friend = it.getValue(Friend::class.java)
Log.d("teste", it.toString())
if (friend != null) {
Log.d("teste", friend.hashMap ? .values.toString())
//friends.add(friend.hashMap?.values.toString())
}
}
}
})
this keeps returning null....
With your Friend class, the Firebase client looks for a JSON for each friend with this structure:
"-LfD9z6ke7FXFjxUb4td": {
"hashMap": {
...
}
},
This is because you're defining your Friend class with a property hashMap like this: class Friend(val hashMap: HashMap < String, String > ? ).
To be able to read your current structure, you'll need to define a data class like this:
data class Friend (
val email: String? = null
}
Now the email in the Friend class matched the email property in the JSON. And since email has a default value, the Friend class will have a default no-argument constructor, which Firebase relies on.
Solved!
After get into /friends
i did this:
var friends : ArrayList<String> = arrayListOf()
the onDataChanged where i get the string friend
override fun onDataChange(p1: DataSnapshot) {
p1.children.forEach { it1 ->
val friend = it1.value as String
friends.add(friend)
}
}
I am trying to access a different context with one variable. Please have a look at the code before:
...
private readonly ClientOneType _contextClientOne;
private readonly ClientTwoType _contextClientTwo;
public ExampleService()
{
_contextClientOne = new ClientOneType();
_contextClientTwo = new ClientTwoType();
}
public Stores[] GetStores(Store storeModel)
{
try
{
var _dynamicContext = null; //this throws an error because c# needs a type for runtime.
if (client == "OutBack")
_dynamicContext = _contextClientOne;
else if(client == "DollarGeneral")
_dynamicContext = _contextClientTwo;
var stores = (from s in _dynamicContext.Store //this is where the magic should take place
where s.StoreName == storeModel.StoreName
select p).ToArray();
return stores;
}
...
}
I get an error when running this because _dynamicContext can not be null so how can i create a variable that can be changed into different contexts?
The lazy solution would be to create different methods for each client, but that wouldn't be very effective as it will become unmaintainable.
I will really appreciate the help. Thank you in advance.
public interface IClientType
{
public Store Store { get; }
}
public class ClientOneType : IClientType
{
...
}
public class ClientTwoType : IClientType
{
...
}
public Stores[] GetStores(Store storeModel)
{
try
{
IClientType _dynamicContext = null;
...
Do ClientOneType and ClientTwoType both derrive from a base class that exposes the property named "Store" ?
I'm guessing they do not, and since they do not, there is no way to use the same variable to write the LINQ query you are writing because the compiler has to be able to determine what properties are available.
however, you could use IQueryable to dynamically build the query
IQueryable<Stores> storeQry=null;
if (client == "Walmart")
storeQry= _contextClientOne.Store.AsQueryable();
else if(client == "CHS")
storeQry= _contextClientTwo.Store.AsQueryable();
var stores = (from s in storeQry
where s.StoreName == storeModel.StoreName
select p).ToArray();
I think I need some feedback on my collection classes - still learning typescript and javascript and these implementations can surely be improved. I am looking forward to any suggestion. I think I do use the generic types in a useful way, any advice here would be appreciated.
The answer I am looking for most is removing the duplicate IHashTable definition from the end of both snippets and moving it to its own file, I cannot get that done it seems. I am even unsure if this IS an interface in the first place. It compiles and works this way, as far as I can see.
The collection types are incomplete and only define the basic most function at the moment. Once I am sure I use the language and its features correct the other functions should not be too difficult.
Here is my HashSet:
import { IHashable } from "./IHashable"
export class HashSet<T extends IHashable> {
private _items: HashTable<T>;
public constructor() {
this._items = {};
}
public Add(key: T): void {
let str: string = key.GetHash();
if (this._items[str] == null) {
this._items[str] = key;
}
else {
throw new RangeError("Key '" + str + "' already exists.");
}
}
public Contains(key: T): boolean {
let str: string = key.GetHash();
return this._items[str] != null;
}
}
interface HashTable<T> {
[key: string]: T;
}
I wonder if I can avoid the checking-before-adding in a way. The javascript-dictionary this relies on does allow duplicates, so to avoid them there is no other way than to check myself?
This is my Dictionary:
import { IHashable } from "./IHashable"
export class Dictionary<T1 extends IHashable, T2> {
private _items: HashTable<KeyValuePair<T1, T2>>;
public constructor() {
this._items = {};
}
public Add(key: T1, value: T2) {
let str: string = key.GetHash();
if (this._items[str] == null) {
let kvp: KeyValuePair<T1, T2> = new KeyValuePair(key, value);
this._items[str] = kvp;
}
else {
throw new RangeError("Key '" + str + "' already exists.");
}
}
public ContainsKey(key: T1): boolean {
let str: string = key.GetHash();
return this._items[str] != null;
}
public Get(key: T1): T2 {
let str: string = key.GetHash();
let kvp: KeyValuePair<T1, T2> = this._items[str];
if (kvp == null) throw new RangeError("Key '" + str + "' not found")
return kvp.Value;
}
}
export class KeyValuePair<T1 extends IHashable, T2> {
private _key: T1;
private _value: T2;
public get Key(): T1 { return this._key; }
public get Value(): T2 { return this._value; }
public constructor(key: T1, value: T2) {
this._key = key;
this._value = value;
}
}
interface HashTable<T> {
[key: string]: T;
}
Both rely on a definition of IHashable (hashABLE and hashTABLE: I should find other names.)
export interface IHashable {
GetHash(): string;
}
The dictionary looks a bit strange, it "wraps" my dictionary into a new type KeyValuePair and then uses this in the javascript dictionary. What I hope to gain by doing this is get my own type for key, in and out, as long as it offers a string by which it can be indexed. - No idea if that makes sense or is completly wrong.
What I am missing is the count of items in the collection, a way to remove items, and a way to iterate over the keys and the values.
Regarding iterating over I will post another question with my implementation of a list and a ForEach over it, hoping iterating the keys or values might be possible in the same way.
Probably the most important question I forgot here: How could the GetHash-Method be build for an own class? I was going to have a static number on my classes, and count up by 1 in the constructor before assign this number to each instance. This would guarantee uniqueness... is there something better?
Thanks for any tip!
Ralf
So I have hundreds of fields in a couple of classes and I'd like to write some methods on them where they automatically println each field and its corresponding value
At the moment I have this:
inner class Version(val profile: Profile) {
#JvmField val MINOR_VERSION = glGetInteger(GL_MINOR_VERSION)
fun write(file: File? = null) {
//file.printWriter().use { out -> out.pri }
this::class.java.fields.forEach {
println(it.isAccessible)
println(it.getInt(it)) }
}
}
But this is what I get:
false
Exception in thread "main" java.lang.IllegalArgumentException: Can not set final int field uno.caps.Caps$Version.MINOR_VERSION to java.lang.reflect.Field
at sun.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:167)
at sun.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:171)
at sun.reflect.UnsafeFieldAccessorImpl.ensureObj(UnsafeFieldAccessorImpl.java:58)
at sun.reflect.UnsafeQualifiedIntegerFieldAccessorImpl.getInt(UnsafeQualifiedIntegerFieldAccessorImpl.java:58)
Any idea?
Instead of using Java fields and Java reflection code, you can also use Kotlin properties and Kotlin reflection classes:
class Reflector {
val Foo = 1;
fun printFields() {
this::class.memberProperties.forEach {
if (it.visibility == KVisibility.PUBLIC) {
println(it.name)
println(it.getter.call(this))
}
}
}
}
It seems that you are passing the Field variable it as a parameter getInt whereas the parameter should be the object the field belongs to this:
From the Javadoc for Field.getInt(Object obj):
obj - the object to extract the int value from
Perhaps this is what you meant to do:
class Reflector {
#JvmField val Foo = 1;
fun printFields() {
this.javaClass.fields.forEach {
println(it.isAccessible)
println(it.getInt(this))
}
}
}
fun main(args : Array<String>) {
Reflector().printFields()
}
I have the following function to access a property's delegate. It uses Kotlin reflection to get a property's name and Java reflection to get the field.
fun Any.getDelegate<T>(prop: KProperty<T>): Any {
return javaClass.getDeclaredField("${prop.name}\$delegate").let {
it.setAccessible(true)
it.get(this)
}
}
The method is used like this:
val delegate = a.getDelegate(A::b)
However, I would prefer to use it like this:
val delegate = a.b.delegate
The problem with the code above is getting the property name of a.b and getting the instance a from a.b. From what I know about Kotlin, this is probably not possible, however I'd like to see if I can clean up my function at all.
To give a bigger picture of what I'm trying do here's my complete code. I want an observable delegate to which I can add and remove observers using the delegate reference and without creating addition variables.
fun Any.addObservable<T>(prop: KProperty<T>, observer: (T) -> Unit) {
getObservableProperty(prop).observers.add(observer)
}
fun Any.getObservableProperty<T>(prop: KProperty<T>): ObservableProperty<T> {
return getDelegate(prop) as ObservableProperty<T>
}
fun Any.getDelegate<T>(prop: KProperty<T>): Any {
return javaClass.getDeclaredField("${prop.name}\$delegate").let {
it.setAccessible(true)
it.get(this)
}
}
class ObservableProperty<T>(
initialValue: T,
initialObservers: Array<(T) -> Unit> = emptyArray()) : ReadWriteProperty<Any?, T> {
private var value = initialValue
public val observers: MutableSet<(T) -> Unit> = initialObservers.toHashSet()
public override fun get(thisRef: Any?, desc: PropertyMetadata): T {
return value
}
public override fun set(thisRef: Any?, desc: PropertyMetadata, value: T) {
this.value = value
observers.forEach { it(value) }
}
}
class A() {
var b by ObservableProperty(0)
}
fun main(args: Array<String>) {
val a = A()
a.addObservable(A::b) {
println("b is now $it")
}
a.b = 1
a.b = 2
a.b = 3
}
Edit:
I just realized that the function also isn't strict because the property delegate field name is referenced by KProperty name, which doesn't require a strong reference to the enclosing class. Here's an example to demonstrate the problem:
class A() {
var foo by ObservableProperty(0)
}
class B() {
var foo by ObservableProperty(0)
}
fun main(args: Array<String>) {
val a = A()
a.addObservable(B::foo) {
println("b is now $it")
}
a.foo = 1
a.foo = 2
a.foo = 3
}
This compiles and runs without error because A::foo and B::foo both result in a field string of "foo$delegate.
Right now reflection is all we can do to get to the delegate object. We are designing a language feature to have direct access to delegate instance, but it's long way to go.
This is how you get the name of a Kotlin Property (although only with an instance of the class). This part will be useful to anyone arriving at this question purely based off its title.
class Stuff(val thing: String)
val stuff = Stuff("cool stuff")
val thingFieldName = "${stuff.thing}\$delegate"
// value of thingFieldName is now "thing"
In terms of getting the delegate itself easier, they say you can now do this:
class Foo {
var bar: String by ReactiveProperty<String>()
}
val foo = Foo()
val bar = foo.bar
val barDelegate = ... // foo.bar$delegate
See ticket.