Develop Reference

Firebase RealtimeDatabase retrieve snapshot object exception

This is my model class
#Parcel
data class ClientModel(
var name: String? = "",
var phone: String? = "",
var princpalAddresse: String? = "",
var homeAddresse: String? = "",
var travailleAddresse: String? = "",
var email: String? = "",
var userToken: String? = "",
var principalAddresseCoords: Pair<Double, Double>? = null,
var homeAddresseCoords: Pair<Double, Double>?= null,
var workAddresseCoords: Pair<Double, Double>? = null,
)
My proGuard file keep the class :
-keep class com.olivier.oplivre.models.ClientModel
But! when I try to get the snapshot with a singleValueEventListener I got exception because of the Pair<Double,Double> variables
val utilisationInfo = snapshot.getValue(ClientModel::class.java) //todo CRASH
Exception :
com.google.firebase.database.DatabaseException: Class kotlin.Pair does not define a no-argument constructor. If you are using ProGuard, make sure these constructors are not stripped.
Database Structure :

I think firebase Realtime database treat your principalAddresseCoords as a list of long so in your ClientModel change the value of principalAddresseCoords to emptyList() and the type List

As #Sami Shorman said , firebase took my Pair instance and transform it but not as list, as Hashmap<,> ! so I changed my class model like that :
var principalAddresseCoords: HashMap<String,Double>? = null,
var homeAddresseCoords: HashMap<String,Double >? = null,
var workAddresseCoords: HashMap<String,Double >? = null,
To put the data as Hashmap I just had to do :
clientModel.workAddresseCoords = HashMap<String,Double>().apply {
put("lat",lat)
put("long",long)
}

Parse Mutable Live Data to Array in Kotlin

There is a mutableLiveData Holding 2 array "deal" and "category" I need to parse this both in different adapters.
Is there a way I can convert 1 mutable live data to 2 array and then parse them to two different adapters
Suppose There is MutableVariable Name se
private lateinit var mHomePojo: MutableLiveData<List<HomePojo>>
having parse Json as below
{
"status": 0,
"response": "success",
"category": [
{
"categoryName": "demo",
"categoryDesc": "demo"
},
{
"categoryName": "demo1",
"categoryDesc": "demo"
}
],
"deal": [
{
"dealImg": "https://aiotechnology.in/Aditechweb/upload/153102117.jpg",
"dealDesc": "gd",
"dealStartDate": "2019-10-18",
"dealEndDate": "2019-10-19"
}
]
}
Is there any way to parse private lateinit var mHomePojo: MutableLiveData<List<HomePojo>> to lateinit var mDealModel: MutableLiveData<List<DealModel>> and
lateinit var mCategoryModel: MutableLiveData<List<CategoryModel>>
I am new to MVVM please help

I think Transformations might be able to help you separate your home live data to two separate livedata object with specified properties. below is piece of code for this. (NOTE : not used lateinit var for example)
private val homeLiveData: LiveData<HomePojo> = MutableLiveData<HomePojo>()
//Category Live data
private val categoryPojo = Transformations.map(homeLiveData) {
it.category
}
//Deal live data
private val dealPojo = Transformations.map(homeLiveData) {
it.deal
}
data class HomePojo(
/*-- Other fields --*/
val category: List<CategoryPojo>? = null,
val deal: List<DealPojo>? = null)
data class CategoryPojo(
val categoryName: String? = null,
val categoryDesc: String? = null)
data class DealPojo(
val dealImg: String? = null,
val dealDesc: String? = null,
val dealStartDate: String? = null,
val dealEndDate: String? = null)

Create an AdapterFactory for gson for dynamic Types

I have a JSON string that I need to converted to data class object in Kotlin, the problem is that there is a field (details) that can have a different structure depending of the value of another field like this
val jsonString1 = "{'name': 'Juan', 'phase': 'step1', 'details': { 'name': 'product 1' }}"
val jsonString2 = "{'name': 'Juan', 'phase': 'step2', 'details': { 'position': 10 }}"
now I have something like
data class Customer(
var name: String? = null
var phase: String? = null
var details: Details? = null
)
data class Details(
var name: String? = null
)
data class Details2(
var position: Int? = null
)
now with gson I know I can
Gson().fromJson(jsonString1, Customer::class.java)
I want to be able to automatically use the right data class depending on the value of the phase field, I know I can create an adapterFactory, but I can't figure out how, an in kotlin is worse
I was reading this post
http://anakinfoxe.com/blog/2016/02/01/gson-typeadapter-and-typeadapterfactory/
and I'm pretty sure is the way to go, but I can't quite get it

Yep, it's pretty easy to write such adapter. I've slightly changed your example:
data class Customer(
var name: String? = null,
var phase: String? = null,
var details: Details? = null
)
sealed class Details {
data class Details1(var name: String? = null) : Details()
data class Details2(var position: Int? = null) : Details()
}
class CustomerDeserializer : JsonDeserializer<Customer> {
override fun deserialize(json: JsonElement, typeOfT: Type?, context: JsonDeserializationContext?): Customer {
val customerObject = json.asJsonObject
val detailsObject = customerObject.getAsJsonObject("details")
val details = if (detailsObject.has("name")) {
Details.Details1(detailsObject.get("name").asString)
} else {
Details.Details2(detailsObject.get("position").asInt)
}
return Customer(
name = customerObject.get("name").asString,
phase = customerObject.get("phase").asString,
details = details
)
}
}
fun main() {
val gson = GsonBuilder()
.registerTypeAdapter(Customer::class.java, CustomerDeserializer())
.create()
println(gson.fromJson(jsonString1, Customer::class.java))
println(gson.fromJson(jsonString2, Customer::class.java))
}

data class Customer(
var name: String? = null
var phase: String? = null
var details: Details? = null
)
data class Details(
var name: String? = null
var position: Int? = null
)
Define Details class in this way
Gson().fromJson(jsonString1, Customer::class.java)
return a Customer either name is null or position is null

Can't convert JSONArray into a list (Kotlin)

This is my string:
{"array":[{"message":"test1","name":"test2","creation":"test3"},{"message":"test1","name":"test2","creation":"test3"}]}
And I want it get that array into a list of object in Kotlin app for Android.
I tried to do it using two examples from this site... So here is my code (res = that string):
val gson = Gson()
val obj = gson.fromJson(res, JsonObject::class.java)
val arr = obj.getAsJsonArray("array")
println(arr.toString())
val list1 : List<JThread> = gson.fromJson(arr, object : TypeToken<List<JThread>>() {}.type)
val list2 = gson.fromJson(arr, Array<JThread>::class.java).asList()
for (x in list1){
println(x.message)
}
for (x in list2){
println(x.message)
}
However I'm only getting null in x.message. I don't know what can go wrong.
I also tried changing arr to arr.toString() everywhere and that didn't work either.
Also JThread is:
object JThread {
var message: String? = null
var name: String? = null
var creation: String? = null }

This can be done without GSON or any other third party library:
#Throws(JSONException::class)
fun JSONObject.toMap(): Map<String, Any> {
val map = mutableMapOf<String, Any>()
val keysItr: Iterator<String> = this.keys()
while (keysItr.hasNext()) {
val key = keysItr.next()
var value: Any = this.get(key)
when (value) {
is JSONArray -> value = value.toList()
is JSONObject -> value = value.toMap()
}
map[key] = value
}
return map
}
#Throws(JSONException::class)
fun JSONArray.toList(): List<Any> {
val list = mutableListOf<Any>()
for (i in 0 until this.length()) {
var value: Any = this[i]
when (value) {
is JSONArray -> value = value.toList()
is JSONObject -> value = value.toMap()
}
list.add(value)
}
return list
}
Usage to convert JSONArray to List:
val jsonArray = JSONArray(jsonArrStr)
val list = jsonArray.toList()
Usage to convert JSONObject to Map:
val jsonObject = JSONObject(jsonObjStr)
val map = jsonObject.toMap()
More info is here

Use this code:
import com.google.gson.annotations.SerializedName
import com.google.gson.Gson
data class Array(
#SerializedName("message")
var message: String,
#SerializedName("name")
var name: String,
#SerializedName("creation")
var creation: String
)
data class Example(
#SerializedName("array")
var array: List<Array>? = null
)
private fun fromJson(json:String):Example{
return Gson().fromJson<Example>(json, Example::class.java)
}
PS: I made it with this site:http://www.jsonschema2pojo.org/

Is it possible to same key with differ class and data type in data class kotlin android?

I have one issue about code data class kotlin android.
How to implement server response? sometimes I get String value or sometime get Object class.
class CMSRespTemp {
data class CMSRespApi(
val status: Boolean = false,
val message: String = "",
val data: String as Data
)
data class Data(
val cms_id: String = "",
val cms_content: String = ""
)
}
When I implement only Data class it works, like this val data: Data or val data: String. But I need together Data and String with key only data.
Is it possible?

When having multiple type for same variable, we can use Any type which is equivalent to Object type in java. So solution is like below :
class CMSRespTemp {
data class CMSRespApi(
val status: Boolean = false,
val message: String = "",
var data: Any? = null // changed it to var from val, so that we can change it's type runtime if required
)
data class Data(
val cms_id: String = "",
val cms_content: String = ""
)
}
And when accessing that variable, one can simply cast like below :
val apiResponse : CMSRespApi //= some API response here from network call
when (apiResponse.data) {
is String -> {
// apiResponse.data will be smart-casted to String here
}
else -> {
val responseData = Gson().fromJson<CMSRespApi.Data>(
Gson().toJsonTree(apiResponse.data),
CMSRespApi.Data::class.java
)
}
}

After 12 Hrs spend and got the solution my self,
val getResultCon = getSerCont.result // response Any
val gson = Gson()
val jsonElement = gson.toJsonTree(getResultCon)
val resultData = gson.fromJson(jsonElement, SearchContactApi.Result::class.java)
Convert your data string to toJsonTree and fromJson with model class then got result.