I use a WebSocket to communicate to a server in my Flutter app. Let's say I receive a JSON object trough the WebSocket :
{
"action": "getProduct",
"cbackid": 1521474231306,
"datas": {
"product": {
"Actif": 1,
"AfficheQte": 0,
"Article": "6"
},
"result": "success"
},
"deviceID": "4340a8fdc126bb59"
}
I have no idea what the content of datas will be until I read the action, and even then, it's not guaranteed to be the same every time. One example of a changing action/datas is when the product doesn't exist.
I can parse it in a Map<String, Object>, but then, how do I access what's inside the Object?
What's the correct way to read this data?
Not sure what the question is about, but you can check the type of the values and then continue accordingly
if(json['action'] == 'getProduct') {
var datas = json['datas'];
if(datas is List) {
var items = datas as List;
for(var item in items) {
print('list item: $item');
}
} else if (datas is Map) {
var items = datas as Map;
for(var key in items.keys) {
print('map item: $key, ${items[key]}');
}
} else if(datas is String) {
print('datas: $datas');
} // ... similar for all other possible types like `int`, `double`, `bool`, ...
}
You also can make that recursive to check list or map values if they are String, ...
Related
I have been trying to parse JSON, which have 3 different set of data where one element have various number of children and sometimes none. I am getting an error when there is no children present or only one present. I declared the JSON as var data.
JSON A
{
"floorplan": [
{
"title": "plan1",
"url": "https://media.plan1.pdf"
},
{
"title": "plan2",
"url": "https://media.plan2.pdf"
}
]
}
JSON B
{"floorplan": []}
JSON C
{
"floorplan": [
{
"title": "plan1",
"url": "https://media.plan1.pdf"
}
]
}
I parsed the JSON like this:
var items = JSON.parse(data);
return {
floorplan1: items.floorplan[0].url;
floorplan2: items.floorplan[1].url;
}
But, it only returned data for the JSON A, for other 2 it gave TypeError: Cannot read property 'url' of undefined.
I modified the code to check if floorplan have at least one child and then parse data.
var items = JSON.parse(data);
var plan = items.floorplan[0];
if(plan){
return {
floorplan1: items.floorplan[0].url;
floorplan2: items.floorplan[1].url;
}
}
The new code returned data for JSON A and B(as empty row), but gave error for C. C have one child still it got the error.
I also tried this code, still got the error for JSON C.
var items = JSON.parse(data);
var plan = items.floorplan[0];
var plan1;
var plan2;
if(plan){
plan1 = items.floorplan[0].url;
plan2 = items.floorplan[1].url;
}
return{
floorplan1 : plan1 ? plan1 : null;
floorplan2 : plan2 ? plan2 : null;
}
Is there any method I can try to get data returned for all 3 types of JSON?
let data = `
[{"floorplan": [{
"title": "plan1",
"url": "https://media.plan1.pdf"
}, {
"title": "plan2",
"url": "https://media.plan2.pdf"
}]},
{"floorplan": []},
{"floorplan": [{
"title": "plan1",
"url": "https://media.plan1.pdf"
}]}]`;
let json = JSON.parse(data);
//console.log(json);
json.forEach(items=>{
//console.log(items);
let o = {
floorplan1: items.floorplan.length > 0 ? items.floorplan[0].url : '',
floorplan2: items.floorplan.length > 1 ? items.floorplan[1].url : ''
};
console.log(o);
o = {
floorplan1: (items.floorplan[0] || {'url':''}).url,
floorplan2: (items.floorplan[1] || {'url':''}).url
};
console.log(o);
o = {
floorplan1: items.floorplan[0]?.url,
floorplan2: items.floorplan[1]?.url
};
console.log(o);
const {floorplan: [one = {url:''}, two = {url:''}]} = items;
o = {
floorplan1: one.url,
floorplan2: two.url
};
console.log(o);
});
Sure. A few ways, and more than I have here. I have put all the raw data into one string, parsed it into json and then iterated through that. In each loop my variable items will correspond to one of the json variables you created and referenced in your question as items.
In the first example, I check to make sure that items.floorplan has at least enough elements to contain the url I'm trying to reference, then use the ternary operator ? to output that URL if it exists or an empty string if it doesn't.
In the second example, I use the || (OR) operator to return the first object that evaluates to true. If items.floorplan[x] exists, then it will be that node, and if it doesn't I provide a default object with an empty url property on the right hand side, and then just use the url from the resulting object.
In the third, I use the optional chaining operator that was introduced in 2020. This method will return undefined if the url doesn't exist.
In the fourth example, I use destructuring to pull values out of the items variable, and make sure that there is a default value for url in case the items variable doesn't have a corresponding value.
But there are many more ways to go about it. These are just a few, and you can't necessarily say which approach is better. It's dependent on your intent and environment. With the exception of optional chaining (which shows undefined if the property doesn't exist), you can see these produce the same results.
DOCS for optional chaining: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Optional_chaining
DOCS for destructuring: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Destructuring_assignment
An article on destructuring: https://javascript.info/destructuring-assignment
{
"vitals": {
"title": "Vitals IR",
"name": "vitalsIr",
"formid":"5ed5f7ca158a91827891cab2"
},
"anthropometry": {
"title": "Anthropometry IR",
"name": "anthropometryIr",
"formid":"5ed621ac158a91228191cafd"
}}
How to get the root key name vitals , anthropometry based on formid value
for example if formid value is "5ed621ac158a91228191cafd"
I need output as anthropometry need to achieve this in angular javascript
To loop through a json object using JavaScript, you can preform a for on the keys. E.g for (jsonPropertyName in json) { ... }. You can then query the formId.
For example:
function ProvideRootKey(formId) {
var results;
for (jsonPropertyName in json) {
if (json[jsonPropertyName]['formid'] === formId) {
results = jsonPropertyName
}
}
return results
}
var json = JSON.parse('{ "vitals":{ "title":"Vitals IR", "name":"vitalsIr","formid":"5ed5f7ca158a91827891cab2"}, "anthropometry":{ "title":"Anthropometry IR", "name":"anthropometryIr", "formid":"5ed621ac158a91228191cafd"}}');
console.log(ProvideRootKey('5ed621ac158a91228191cafd'))
Output (in console log):
"anthropometry"
See working example: https://jsfiddle.net/vgo81stm/1/
I have followed an example shown here
link
And i got the hang of it, i managed to create my own "Employee" entity and i found some dummy api data online to play with.
like this Problem is, the tornadofx throws null pointer error, and i think its because the rest response sends something like this
{
"status": "success",
"data": [
{
"id": "1",
"employee_name": "Tiger Nixon",
"employee_salary": "320800",
"employee_age": "61",
"profile_image": ""
},
but when i use mocky and provide JUST the json part
[
{
"id": "1",
"employee_name": "Tiger Nixon",
"employee_salary": "320800",
"employee_age": "61",
"profile_image": ""
},...]
it all works fine.
I think those additional fields "status" and "success" in response confuse the rest client of tornadofx, and i cant manage to get it to work, is there anyway to tell client to ignore every other fields besides those of json data.
All links are functional, so you can try yourself.
full working example
package com.example.demo.view
import javafx.beans.property.SimpleIntegerProperty
import javafx.beans.property.SimpleStringProperty
import javafx.scene.layout.BorderPane
import tornadofx.*
import javax.json.JsonObject
class Employee (id:Int?=null , name: String? = null, age: Int?=null): JsonModel {
val idProperty = SimpleIntegerProperty(this, "id")
var id by idProperty
val ageProperty = SimpleIntegerProperty(this, "age")
var age by ageProperty
val employeeNameProperty = SimpleStringProperty(this, "name", name)
var name by employeeNameProperty
override fun updateModel(json: JsonObject) {
with(json) {
id = int("id")!!
age = int("employee_age")!!
name = string("employee_name")
}
}
override fun toJSON(json: JsonBuilder) {
with(json) {
add("id", id)
add("employee_name", name)
add("employee_age", age)
}
}
}
class PersonEditor : View("Person Editor") {
override val root = BorderPane()
val api : Rest by inject()
var persons = listOf(Employee(1,"John", 44), Employee(2,"Jay", 33)).observable()
val model = PersonModel(Employee())
init {
api.baseURI = "https://run.mocky.io/v3/"
val response = api.get("f17509ba-2d12-4c56-b441-69ab23302e43")
println(response.list())
println(response.list().toModel<Employee>()[0].name)
// print( p.get(1))
with(root) {
center {
tableview(response.list().toModel<Employee>()) {
column("Id", Employee::idProperty)
column("Name", Employee::employeeNameProperty)
column("Age", Employee::ageProperty)
// Update the person inside the view model on selection change
model.rebindOnChange(this) { selectedPerson ->
item = selectedPerson ?: Employee()
}
}
}
right {
form {
fieldset("Edit person") {
field("Id") {
textfield(model.id)
}
field("Name") {
textfield(model.name)
}
field("Age") {
textfield(model.age)
}
button("Save") {
enableWhen(model.dirty)
action {
save()
}
}
button("Reset").action {
model.rollback()
}
}
}
}
}
}
private fun save() {
// Flush changes from the text fields into the model
model.commit()
// The edited person is contained in the model
val person = model.item
// A real application would persist the person here
println("Saving ${person.employeeNameProperty} / ${person.ageProperty}")
}
}
class PersonModel(person: Employee) : ItemViewModel<Employee>(person) {
val id = bind(Employee::idProperty)
val name = bind(Employee::employeeNameProperty)
val age = bind(Employee::ageProperty)
}
if you replace base url and send request to http://dummy.restapiexample.com/api/v1/employees you will get an error that i am talking about
Your call to mocky returns a list, so .list() works fine. Your call to restapiexample, however, returns an object, not a list, so .list() won't do what you expect. You can probably use something like this, though I haven't tested it:
response.one().getJsonArray("data").toModel<Employee>()[0].name)
Further explanation:
If you're not familiar with the structure of JSON, check out the diagrams on the JSON homepage.
TornadoFX has two convenience functions for working with JSON returns: .list() and .one(). The .list() function will check if the result is a JsonArray. If so, it simply returns it. If it is instead a JsonObject, it wraps that object in a list and returns the new list.
In your case, since restapiexample is returning an object, the result of your call to .list() is a JsonArray with a single object. It looks something like this:
[
{
"status": "success",
"data": [...]
}
]
Obviously that single object cannot be converted to an Employee, so dereferencing anything off of it will result in a NullPointerException.
The .one() function on the other hand will check if the response is a JsonObject. If it is, it simply returns the object. If, however, the response is a JsonArray, it will take the first item from the array and return that item.
Say I have a JSON request payload like
{
"workflow": {
"approvalStore": {
"sessionInfo": {
"user": "baduser"
},
"guardType": "Transaction"
}
}
}
I get the value of user via
def user = req.get("workflow").get("approvalStore").get("sessionInfo").get("user")
Now, I get a RestResponse approvalList which I store as list and return to caller as return approvalList.json as JSON. All well so far.
Suppose the response (approvalList.json) looks like below JSONArray -
[
{
"objId": "abc2",
"maker": "baduser"
},
{
"objId": "abc1",
"maker": "baduser"
},
{
"objId": "abc4",
"maker": "gooduser"
}
]
Question : How may I filter the approvalList.json so that it doesn't contain entries (objects) that have "maker": "baduser" ? The value passed to maker should essentially be the user variable I got earlier.
Ideal required output -
It's not entirely clear if you always want a single object returned or a list of objects but using collect is going to be the key here:
// given this list
List approvalList = [
[objId: "abc2", maker: "baduser"],
[objId: "abc1", maker: "baduser"],
[objId: "abc4", maker: "gooduser"]
]
// you mentioned you wanted to match a specific user
String user = "baduser"
List filteredList = approvalList.findAll{ it.maker != user}
// wasn't sure if you wanted a single object or a list...
if (filteredList.size() == 1) {
return filteredList[0] as JSON
} else {
return filteredList as JSON
}
Pretty simple. First parse the JSON into an object, then walk through and test.
JSONObject json = JSON.parse(text)
json.each(){ it ->
it.each(){ k,v ->
if(v=='baduser'){
// throw exception or something
}
}
}
I'm working on something that involved using the Bit.ly API, and allow the user to select theformat (Text, XML, Json) the text & XML are completed. This is the Json result that is returned when you shorten a URL:
{
"status_code": 200,
"status_txt": "OK",
"data":
{
"long_url": "http:\/\/panel.aspnix.com\/Default.aspx?pid={Removed}",
"url": "http:\/\/rlm.cc\/gtYUEd",
"hash": "gtYUEd",
"global_hash": "evz3Za",
"new_hash": 0
}
}
And this C# code works just fine to parse it and get the short URL:
var serializer2 = new JavaScriptSerializer();
var values2 = serializer2.Deserialize<IDictionary<string, object>>(json);
var results2 = values2["data"] as IDictionary<string, object>;
var shortUrl2 = results2["url"];
expandedUrl = results2["url"].ToString();
return results2["url"].ToString();
Now here's the Json sent back when expanding a URL:
{
"status_code": 200,
"status_txt": "OK",
"data":
{
"expand":
[
{
"short_url": "http:\/\/rlm.cc\/gtYUEd",
"long_url": "http:\/\/panel.aspnix.com\/Default.aspx?pid={Removed}",
"user_hash": "gtYUEd",
"global_hash": "evz3Za"
}
]
}
}
Ad that's where my problem begins, how can I change my current C# to be able to handle both scenarios, because as you can see their vastly different from each other. Any ideas?
I usually use Json.NET to cherrypick values out of JSON documents. The syntax is very concise. If you reference NewtonSoft.Json.dll and use Newtonsoft.Json.Linq, you can write the following:
var job = JObject.Parse(jsonString);
if (job["data"]["expand"] == null)
{
Console.WriteLine((string)job["data"]["url"]);
}
else
{
Console.WriteLine((string)job["data"]["expand"][0]["long_url"]);
}
If jsonString is:
string jsonString = #"{""status_code"": 200, ""status_txt"": ""OK"", ""data"": {""long_url"": ""http:\/\/panel.aspnix.com\/Default.aspx?pid={Removed}"", ""url"": ""http:\/\/rlm.cc\/gtYUEd"", ""hash"": ""gtYUEd"", ""global_hash"": ""evz3Za"", ""new_hash"": 0 }}";
the routine will display http://rlm.cc/gtYUEd.
If jsonString is:
string jsonString = #"{""status_code"": 200, ""status_txt"": ""OK"", ""data"": { ""expand"": [ { ""short_url"": ""http:\/\/rlm.cc\/gtYUEd"", ""long_url"": ""http:\/\/panel.aspnix.com\/Default.aspx?pid={Removed}"", ""user_hash"": ""gtYUEd"", ""global_hash"": ""evz3Za"" } ] } }";
the routine will display http://panel.aspnix.com/Default.aspx?pid={Removed}.
Not sure I got your problem. Why aren't you testing, if you got a shortening result or a expanding result? Since they are different, this could easily be done via simple 'if ()' statements:
if (results2.ContainsKey("expand")) {
// handle the expand part
} else {
// handle the shorten part
}
Assuming that the provider is consistent with which form it sends, do you need to have code that handles both? It should be direct to handle each individually.
If you can't know ahead of time which format you will get back, you can do the following:
if (results2.ContainsKey("expand"))
{
//Second example
}
else
{
//First example
}