I have an array of structs that has been decoded from a JSON file. Each struct has a stored property that is a variable-dimension array stored in an enum associated value.
Some of the structs have property Enum.array2D([[Float]]) and others have Enum.array3D([[[Float]]])
Is there a simple or elegant way to extract a variable-type associated value from the struct's enum property - maybe with a getter function? Currently, the only way I know how to do this is with an external switch anytime I want to access the underlaying value. For example, somewhere in external code I have to use this anytime I want to get these values and manipulate them:
switch structArray[index].enumProperty {
case .array2D(let array2Val):
// Do stuff with the 2D array
case .array3D(let array3Val):
// Do stuff with the 3D array
}
I have considered adding each of the two possible types as optionals and setting the correct one in the init function with a switch, but that seems inefficient as I’ll have the arrays stored in two places.
Related
There appears to be few options to validate the source JSON used when unmarshalling to a struct. By validate I mean 3 main things:
a required field exists in the JSON
the field is the correct type (e.g. don't force a string into an integer)
the field contains a valid value (value range / enum)
For nested structs, I simply mean where an attribute in one struct has the type of another struct:
type Example struct {
Attr1 int `json:"attr1"`
Attr2 ExampleToo `json:"attr2"`
}
type ExampleToo struct {
Attr3 int `json:"attr3"`
}
And this JSON would be valid:
{"attr1": 5, "attr2": {"attr3": 0}}
To keep this simple, I'll focus simply on integers. The concept of "zero values" is the first issue. I could create an UnmarshalJSON method, which is detected by JSON packages, including the standard encoding/json package. The problem with this approach is that is that is does not support nested structs. If ExampleToo has an UnmarshalJSON method, the ExampleToo.UnmarshalJSON() method is never called if unmarshalling to an Example object. It would be possible to write a method Example.UnmarshalJSON() that recursively handled validation, but that seems extremely complex, especially if ExampleToo is reused in many places.
So there appears to be some packages like the go-playground/validator where validation can be specified both as functions and tags. However, this works on the struct created, and not the JSON itself. So if a field is tagged as validation:"required" on an integer, and the integer value is 0, this will return an error because 0 is both a valid value and the "zero value" for integers.
An example of the latter here: https://go.dev/play/p/zqSUksPzUiq
I could also use pointers for everything, checking for nil as missing values. The main problem with that is that it requires dereferencing on each use and is a pretty uncommon practice for things like integers and strings.
One thing that I have also considered is a "sister struct" that uses pointers to do validation for required fields. The process would basically be to write a validation method for each struct, then validate that sister struct. If it works, then deserialize the main struct (without pointers). I haven't started on this, just a concept I've thought about, but I'm hoping there are better validation options.
So... is there a better way to do JSON/YAML input validation on nested structs? I'm happy to mix methods where say UnmarshalJSON is used for doing some work like verifying fields exist, but I'd like to pass that back to the library to let it continue to call UnmarshalJSON on subsequent nested structs. I'd also rather defer to the JSON library for casting values into the struct, etc.
I got an anonymous array which I want to deserialize, here the example of the first array object
[
{ "time":"08:55:54",
"date":"2016-05-27",
"timestamp":1464332154807,
"level":3,
"message":"registerResourcePath ('', '/sap/bc/ui5_ui5/ui2/ushell/resources/')",
"details":"","component":"sap.ui.ModuleSystem"},
{"time":"08:55:54","date":"2016-05-27","timestamp":1464332154808,"level":3,"message":"URL prefixes set to:","details":"","component":"sap.ui.ModuleSystem"},
{"time":"08:55:54","date":"2016-05-27","timestamp":1464332154808,"level":3,"message":" (default) : /sap/bc/ui5_ui5/ui2/ushell/resources/","details":"","component":"sap.ui.ModuleSystem"}
]
I tried deserializing using CL_TREX_JSON_SERIALIZER, but it is corrupt and does not work with my JSON, here is why
Then I tried /UI2/CL_JSON, but it needs a "structure" that perfectly fits the object given by the JSON Object. "Structure" means in my case an internal table of objects with the attributes time, date, timestamp, level, messageanddetails. And there was the problem: it does not properly handle references and uses class description to describe the field assigned to the field-symbol. Since I can not have a list of objects but only a list of references to objects that solution also doesn't works.
As a third attempt I tried with the CALL TRANSFORMATION as described by Horst Keller, but with this method I was not able to read in an anonymous array, and here is why
My major points:
I do not want to change the JSON, since that is what I get from sap.ui.log
I prefere to use built-in functionality and not a thirdparty framework
Your problem comes out not from the anonymity of array, but from the awkwardness of SAP JSON (De)serializer, which doesn't respect double quotes, which enclose JSON attributes. The issue is thoroughly described in this answer.
If you don't want to change your JSON on-the-fly, the only way you have is to change CL_TREX_JSON_DESERIALIZER class like this.
/UI5/CL_JSON_PARSER parses JSONs with unknown format.
Note that it's got "for internal use" written on it so many times that you probably should take it seriously and clone its code to fixate it.
I am trying to add data from the Scope to an Array.
In my example I have $scope.employee which have several other fields, like name, number, email, etc.
So when I push the data to the Array I use:
array.push($scope.employee);
This works, because it adds the data to the array, but the binding still applies, so if I later on change thing in the scope, the data in the array also changes. I want this array to be static and not change. Just to hold the elements I have passed into it.
I would like to only add the data from the $scope.employee and not the binding.
I know it's possible to:
array.push({name: $employee.name, number: $employee.number});
But the $scope.employee have many fields, therefore I want to push the whole object.
You want to use angular.copy to make a deep copy without the pointers.
array.push(angular.copy($scope.employee));
documentation
I have a data which are object array. It contains object arrays in a tree structure. I use JSON.stringify(myArray) but the data still contain array because I see [] inside the converted data.
In my case, I want all the data to be converted into json object not array regarding I need to used the data on TreeTable of SAPUI5.
Maybe I misunderstand. Please help me clear.
This is the example of the data that I got from JSON.stringify.
[{"value":{"Id":"00145E5BB2641EE284F811A7907717A3",
"Text":"BI-RA Reporting, analysis, and dashboards",
"Parent":"00145E5BB2641EE284F811A79076F7A3","Type":"BMF"},
"children":[{"value":{"Id":"00145E5BB2641EE284F811A7907737A3",
"Text":"WebIntelligence_4.1","Parent":"00145E5BB2641EE284F811A7907717A3",
"Type":"TWB"},"children":[{"value":{"Id":"00145E5BB2641EE284F811A7907757A3",
"Text":"Functional Areas","Parent":"00145E5BB2641EE284F811A7907737A3","Type":"TWB"},
"children":[{"value":{"Id":"00145E5BB2641EE284F811A7907777A3",
"Text":"CHARTING","Parent":"00145E5BB2641EE284F811A7907757A3","Type":"TWB"},
"children":[{"value":{"Id":"001999E0B9081EE28AB706BE26631E93",
"Text":"Drill","Parent":"00145E5BB2641EE284F811A7907777A3","Type":"TWB"},
"children":[{"value":{"Id":"001999E0B9081EE28AB706BE26633E93",
"Text":"[AUTO][ACCEPT] Drill on charts DHTML","Parent":"001999E0B9081EE28AB706BE26631E93",
"Type":"TWB","Ref":"UT_WEBI_CHARTS_DRILL_HTML"}},{"value":{"Id":"001999E0B9081EE28AB706BE26635E93",
"Text":"[AUTO][ACCEPT] Drill on charts JAVA","Parent":"001999E0B9081EE28AB706BE26631E93",
"Type":"TWB","Ref":"UT_WEBI_CHARTS_DRILL_JAVA"}}]},...
The output that I want shouldn't be array of object but should be something like...
{{"value":{
"Id":"00145E5BB2641EE284F811A7907717A3",
"Text":"BI-RA Reporting, analysis, and dashboards",
"Parent":"00145E5BB2641EE284F811A79076F7A3","Type":"BMF"},
"children":{
{"value":{
"Id":"00145E5BB2641EE284F811A7907737A3",
"Text":"WebIntelligence_4.1",
"Parent":"00145E5BB2641EE284F811A7907717A3",
"Type":"TWB"},
"children":{
{"value":{
"Id":"00145E5BB2641EE284F811A7907757A3",
"Text":"Functional Areas",
"Parent":"00145E5BB2641EE284F811A7907737A3",
"Type":"TWB"},...
JSON.stringify merely converts JavaScript data structures to a JSON-formatted string for consumption by other parsers (including JSON.parse). If you want it to stringify to a different value, you must change the source data structures first.
However, it seems that this can't be represented as anything other than an array because you have duplicate keys (i.e. value appears more than once). That would not be valid for a JavaScript object or a JSON representation of such.
I think what you want is
JSON.stringify(data[0]);
or perhaps
JSON.stringify(data[0].value);
where data is the object you passed in the question
I have an interesting problem to solve that would be helped by successfully casting objects created by LINQ to SQL into a single master object that I could pass around. Here is the scenario at a high level.
I have a number of stored procedures that fetch data and then all return the exact same columns. The params into the procs and the logic vary greatly, so a single proc will not work. Then Linq creates a strongly typed object which is used throughout my application as parameter and return values.
I am using these strongly typed objects as noted above as parameters and return values in a series of filters used to analyze stocks. My client would like to change the order the order of the filters. The issue is that each succeeding filter will only work on what passed the last filter.
Currently I am hard coding my parameters, and if I could create a master object that I could cast any of these Linq objects to, I could then always pass and return the master object.
I have read the materials available on the internet about casting between different types such as static to anonymous types or a list of integers and an array list containing objects representing integers, but I need to actually cast one object into another.
What general direction would I take to solve this problem of converting strongly typed objects generated by linq that are exactly the same into a single master object?
Thank you for any of your thoughts.
If all your linq objects have the same fields, you could have them implement an interface defined with those common fields. Then the calls to your filter methods can depend on an interface rather than a specific implementation. In other words, the parameters in the filter methods will be of the interface type rather than a linq class type.
e.g.: Where ICommonFields is an interface you define with all the common fields in each l2s class -
public class Filterer
{
public ICommonFields filterStuff(ICommonFields x)
{
//do stuff
}
}
or -
public class Filterer
{
public T filterStuff<T>(T x)
where T: class, ICommonFields, new()
{
//do stuff
}
}
I'd prefer the generic version, as T becomes the actual type rather than a reference through an interface - linq-to-sql has issues when using a type through an interface with query expressions.
Edit: sorry, it was late when i first wrote this response (likely excuse! :). Fixed my obvious mistake with the example code :)
Although there might be a way to do this with casting, I'm going to offer you a quick and dirty solution - and I'm assuming that your resultant objects are collection-based:
Given that all of your child objects
all share the same columns, go ahead
and pick one of them to act as your
master object - then simply iterate
through the rows of your other LINQ
objects and add them to the collection
of your master object. If your
resultant object is a strongly typed
data table, then all you'd do is Add
to the .Rows collection.
Additionally, you might be able to just add the elements retrieved some subsequent LINQ queries directly to your master object depending upon how you write your SELECT causes in LINQ.