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FreeMarker template error: JSONArray wrapped into f.e.b.StringModel

i'm trying to send JSON object to my free marker, but i getting error while testing JUnit
here is my object
{
"filename": "test",
"orderId": "123435",
"orderDate": "23.09.2020г.",
"itemsCount": "4",
"items": [
{
"itemName": "ТВ Приставка 400",
"itemCount": "2 шт Х 400₽",
"itemSum": "800.00"
}
],
"totalSumm": "3000.00"
}
here is my error:
FreeMarker template error:
The value you try to list is an extended_hash+string (org.camunda.bpm.engine.impl.util.json.JSONArray wrapped into f.e.b.StringModel), thus you must specify two loop variables after the "as"; one for the key, and another for the value, like <#... as k, v>).
how could i resolve it?
items is a arrays of JSON objects

FreeMarker knows nothing about org.camunda.bpm.engine.impl.util.json.JSONArray, so it doesn't see it as a list-like thing (as a sequence, as it's called in FTL). So you can do one of these:
Using the objectWrapper Configuration setting, you teach FreeMarker how to treat JSONArray as a list. (You can find more about custom ObjectWrapper-s elsewhere.) Then you can just #list such objects, and use all the other operations applicable to sequences.
Or, you call the Java API-s of JSONArray from the template. That will be less convenient of course, but requires no prior investment.

Compile time check while passing values to a function in Kotlin Android

I am taking a JSON file as input for a class and parsing the values using gson through respective data classes.
I want to call a function that takes a String value as an argument.
The string value allowed is decided from the values parsed from JSON file. Can I somehow check for that string value passed to the function at compile-time & give an error at compile-time?
Or If I can allow only certain values in the argument for the function based on the values from JSON
Detailed Explanation of use case:
I am building a SDK in which a the person using sdk inputs json String. The json is standardised and is parsed in my code.
{
"name": "Test",
"objects": [
{
"name": "object1",
"type": "object1"
}
]
}
Here name values and other values may vary based on the input by the developer using it but key remains same. But we need to call a function using the value in objects name parameter.
fun testMethod(objectName:String)
So developer calls the testMethod as testMethod(object1).
I need to validate object1 parameter based on json but is there any way possible restricting the test method parameter to object1 only & give error at compile time if the developer calls testMethod(obj1)
Right now I parse JSON & have checks inside the testMethod()

Sure it's possible to do, but somehow in different way, that you described. First of all, as you already mentioned this behavior could be done easily. For this purpose we have Objects.requireNotNull() or Guava.Preconditions(). At the same way you can define you checking but this will work on runtime only.
To do in compile time, you need to create Annotation Preprocessor. The same, as did in different libraries, and one of them, could be Lombok, with their NotNull and Nullable. Android annotation just provide mark and bound for IDE warning, but in their case they adding NotNull checking and throw exception for every annotation usage during compile time.
It's not an easy way, but it's what you are looking for.

No, it's impossible check it in compiler time. It's string handling, as numeric calculation.
In my app, I convert string to JSON and JSON to string, passing class descriptor. My aim is record JSON string in a text file to load in SQLite database. This code I've run in my desktop computer not in Android.
data class calcDescr (
...
)
val calc = CalcDescr(...)
// toJson: internal Kotlin data to JSON
val content = Gson().toJson(calc)
//==================
// Testing validity
// ================
// fromJson: JSON to internal Kotlin data.
// It needs pass the class descriptor. Uses *Java* token, but it's *Kotlin*
var testModel = Gson().fromJson(content, CalcDescr::class.java)
// toJson: internal Kotlin data to JSON again
var contentAgain = Gson().toJson(testModel)
// shoul be equal!
if (content == contentAgain) println("***ok***")
In my file, I write the variable content in a file

Unable to Pass Valid JSON Between Lambda Functions

I am having trouble passing valid JSON between two different Java AWS Lambda functions. The first function generates rawJson "String" that is formatted like this:
rawJson: [
{
"id": 1,
"createdOn": 1535177185000,
"text": "test text"
}
]
This is passed to a second Lambda function:
request.withFunctionName(FUNCTION_NAME).withPayload(rawJson);
awsLambdaClient.invoke(request);
At the beginning of the second Lambda function, I print the value of the input Object:
inputObject: [{id=1, createdOn=1535177185000, text=test text}]
The quotes have been stripped and this is no longer valid JSON. Any attempt to map this back to my POJOs (or to even have my Lambda function accept a "String" like it should, instead of an "Object") results in a JSON-related exception.
Why is my valid JSON becoming malformed between the two Lambdas?

This was my fault. Like I mentioned, I had a RequestHandler like this:
RequestHandler<Object, Void>
That wasn't necessary. Lambda is smart enough on its own to serialize and deserialize my objects. Works fine with my code updated to:
RequestHandler<List<MyClass>, Void>

Which is the proper way to work with complex types (lists and objects) in Jaspersoft?

Please consider a MongoDB collection with the following document:
"_id": "clientsInfo"
"data": {
"clientsList" : [
{
"name" : "Mike",
"country" : "USA"
},
...
]
}
After setting the DataSet and defining the Query like this...
{
collectionName:'projectA',
findQuery: {
'_id':'clientsInfo',
},
findFields: {
'_id':0,
'data.clientsList':1
},
}
...I am able to display the first item of the fetched array (java.util.List type) in JasperSoft Studio inside a Text Field using the following expression:
$F{data.clientsList}.get(0)
But, considering that I would like to exhibit the whole data in a Name/Country Table...
Question1: How could I access any of the dictionary fields? Trying get method I obtain The method get(String) is undefined for the type Object. error. However, knowing that the object is an instance of com.mongodb.BasicDBObject it should have that method inherited (See doc).
I have also tried to cast object to org.json.JSONObject but then I get net.sf.jasperreports.engine.fill.JRExpressionEvalException: Error evaluating expression for source text: (JSONObject)$F{data.clientsList}.get(0) error.
Question2: Let's suppose we have already solved first question... How can I iterate the list to access not only the first item but all of them according to the array length? Is it possible to use for-loop sentence inside the JasperSoft Expression Editor? (if-then-else seems to be available)
Thanks in advance, Any clue that point me in the right direction will be appreciated.

Just in case someone was in the same situation as I was, I must say this whole approach was wrong.
It's not about making a simple query which returns big block of complex data formatted as an object or list of objects and then manipulate it with JasperSoft Studio. Instead, what I had to do was design a more elaborated query which returns the simple fields I wanted to use straightforward. How to do this? By using Aggregation Framework.
So, by changing this...
{
collectionName:'projectA',
findQuery: {
'_id':'clientsInfo',
},
findFields: {
'_id':0,
'data.clientsList':1
},
}
...for this...
{
runCommand: {
aggregate : 'projectA',
pipeline : [
{'$match': {'_id':'clientsInfo'}},
{'$project': {'data.clientsList': 1}},
{'$unwind': '$data'},
{'$unwind': '$data.clientsList'}
]
}
}
...is how I get name and country fields in order to use them in Text Fields, Tables, ...etc.

What are the best practices to add metadata to a RESTful JSON response?

Background
We are building a Restful API that should return data objects as JSON. In most of the cases it fine just to return the data object, but in some cases, f.ex. pagination or validation, we need to add some metadata to the response.
What we have so far
We have wrapped all json responses like this example:
{
"metadata" :{
"status": 200|500,
"msg": "Some message here",
"next": "http://api.domain.com/users/10/20"
...
},
"data" :{
"id": 1001,
"name": "Bob"
}
}
Pros
We can add helpful metadata to the response
Cons
In most cases we don't need the metadata field, and it adds complexity to the json format
Since it's not a data object any more, but more like a enveloped response, we can not use the response right away in f.ex backbone.js without extracting the data object.
Question
What is the best practices to add metadata to a json response?
UPDATE
What I've got so far from answers below:
Remove the metadata.status an return the http response code in the
http protocol instead (200, 500 ...)
Add error msg to body of an http 500 repsonse
For pagination i natural to have some metadata telling about the pagination structure, and the data nested in that structure
Small amount of meta data can be added to http header (X-something)

You have several means to pass metadata in a RESTful API:
Http Status Code
Headers
Response Body
For the metadata.status, use the Http Status Code, that's what's for!
If metadata is refers to the whole response you could add it as header fields.
If metadata refers only to part of the response, you will have to embed the metadata as part of the object.DON'T wrap the whole response in an artifical envelope and split the wrapper in data and metadata.
And finally, be consistent across your API with the choices you make.
A good example is a GET on a whole collection with pagination. GET /items
You could return the collection size, and current page in custom headers. And pagination links in standard Link Header:
Link: <https://api.mydomain.com/v1/items?limit=25&offset=25>; rel=next
The problem with this approach is when you need to add metadata referencing specific elements in the response. In that case just embed it in the object itself. And to have a consistent approach...add always all metadata to response. So coming back to the GET /items, imagine that each item has created and updated metadata:
{
items:[
{
"id":"w67e87898dnkwu4752igd",
"message" : "some content",
"_created": "2014-02-14T10:07:39.574Z",
"_updated": "2014-02-14T10:07:39.574Z"
},
......
{
"id":"asjdfiu3748hiuqdh",
"message" : "some other content",
"_created": "2014-02-14T10:07:39.574Z",
"_updated": "2014-02-14T10:07:39.574Z"
}
],
"_total" :133,
"_links" :[
{
"next" :{
href : "https://api.mydomain.com/v1/items?limit=25&offset=25"
}
]
}
Note that a collection response is an special case. If you add metadata to a collection, the collection can no longer be returned as an array, it must be an object with an array in it. Why an object? because you want to add some metadata attributes.
Compare with the metadata in the individual items. Nothing close to wrapping the entity. You just add some attributes to the resource.
One convention is to differentiate control or metadata fields. You could prefix those fields with an underscore.

Along the lines of #Charlie's comment: for the pagination part of your question you still need to bake the metadata into the response somhow, but the status and message attributes here are somewhat redundant, since they are already covered by the HTTP protocol itself (status 200 - model found, 404 - model not found, 403 - insufficient privs, you get the idea) (see spec). Even if your server returns an error condition you can still send the message part as the response body. These two fields will cover quite much of your metadata needs.
Personally, I have tended towards (ab)using custom HTTP headers for smaller pieces of metadata (with an X- prefix), but I guess the limit where that gets unpractical is pretty low.
I've expanded a bit about this in a question with a smaller scope, but I think the points are still valid for this question.

I suggest you to read this page https://www.odata.org/ You are not forced to use OData but the way they do the work is a good example of good practice with REST.

We had the same use case, in which we needed to add pagination metadata to a JSON response. We ended up creating a collection type in Backbone that could handle this data, and a lightweight wrapper on the Rails side. This example just adds the meta data to the collection object for reference by the view.
So we created a Backbone Collection class something like this
// Example response:
// { num_pages: 4, limit_value: 25, current_page: 1, total_count: 97
// records: [{...}, {...}] }
PageableCollection = Backbone.Collection.extend({
parse: function(resp, xhr) {
this.numPages = resp.num_pages;
this.limitValue = resp.limit_value;
this.currentPage = resp.current_page;
this.totalCount = resp.total_count;
return resp.records;
}
});
And then we created this simple class on the Rails side, to emit the meta data when paginated with Kaminari
class PageableCollection
def initialize (collection)
#collection = collection
end
def as_json(opts = {})
{
:num_pages => #collection.num_pages
:limit_value => #collection.limit_value
:current_page => #collection.current_page,
:total_count => #collection.total_count
:records => #collection.to_a.as_json(opts)
}
end
end
You use it in a controller like this
class ThingsController < ApplicationController
def index
#things = Thing.all.page params[:page]
render :json => PageableCollection.new(#things)
end
end
Enjoy. Hope you find it useful.

How about returning directly the object that you want in data, like return:
{
"id": 1001,
"name": "Bob"
}
And return in headers the metadata.
Option 1 (one header for all metadata JSON):
X-METADATA = '{"status": 200|500,"msg": "Some message here","next": "http://api.domain.com/users/10/20"...}'
Option 2 (one header per each metadata field):
X-METADATA-STATUS = 200|500
X-METADATA-MSG = "Some message here",
X-METADATA-NEXT = "http://api.domain.com/users/10/20"
...
Until now I was using like you, a complex JSON with two fields, one for data and one for metadata. But I'm thinking in starting using this way that I suggested, I think it will be more easy.
Remind that some server have size limit for HTTP headers, like this example: https://www.tutorialspoint.com/What-is-the-maximum-size-of-HTTP-header-values

JSON:API solves this by defining top-level meta and data properties.