I'm new to Swift and I have to serialize an object structure into a JSON string in my iOS( iOS >= 8) project.
So I decided to use the ObjectMapper library (I integrated it with Cocoapod).
But my problem is that the structure is the following.
ObjectA can have a list of children objects as an array stored in an instance variable.
Objects that can be stored in the instance array can be of multiple types, say ObjectB and ObjectC. So, in Java with GSON I would have created an InterfaceD and made both of my classes implement it and made the array in ObjectA store InterfaceD types, but I can't figure how to do this with Swift object model as it results in empty {} JSON objects.
The resulting JSON should look like this.
{"children":[
{"type":"ObjectB", "value1":"foo"},
{"type":"ObjectC", "value1":"bar", "value2":"baz"}
]}
and I get
{"children":[
{},
{}
]}
Notice that the two entries that have to be serialized from objectA and ObjectC should have different structures.
I tried multiple things but each times I'm stuck in a dead end.
I tried using generics, tried to use Mappable protocol as my array type, I tried classic class inheritence but any one failed.
Have you any idea how I can achieve this ?
Note that I know that I could add a serialization function to each object and retrieve the strings recursively and concatenate them. But I really want to avoid implementing a JSON serializer by myself as I already use on successfully as Alamofire is already used in the project). Also implementing a new serializer is error prone and not a clean way to solve the problem IMO.
Thanks a lot.
I never had the solution but as a workaround I just made my objects produce a dictionnary from all its values. Then I recursively add child objects dictionnaries as the current dictionnary values.
It adds a toDict() function to each object that I forced with a protocol.
When the resulting object is only made of a tree of dictionnaries, the ObjectMapper serialization works fine...
Related
I'm using Realm.io as database and I need a select * from all_tables in Realm.
I mean a method returning an RLMArray, but I have not found anything about this.
I need the class reference, such as Realm Browser.
Thanks.
You can use [realm.schema.objectSchema valueForKey:#"className"] to get an NSArray of all of the RLMObject subclasses used in the Realm.
I don't believe this is possible at the moment. You should request it on github. In the mean time you will have to create your own. First you have to know that an RLMArray can only hold one type so if in these different tables there are different types than you can not do the following. It would be as easy as creating your own method for this. It would consist of getting all objects from each table and just inserting them into the RLMArray; If your tables don't have the same type then you will have to use a NSMutableArray or an NSArray.
I just want the RestKit to parse the JSON data into NSDictionary, but not a class. This is because the attributes of the JSON data is dynamic, means the number of fields is not fixed and field count can be large. So I don't want to create a huge class to map the json data. Just keep that in NSDictionary. Does RestKit provide this functionality or we have to work out some other way.Guidance Needed.
Thanks.
Have to modify the Restkit to support the ability ....
RKObjectRequestOperation.HTTPRequestOperation.responseData
then parse the json data to dictionary or array
Either use AFNetworking (which RestKit is built on top of) or use a dynamic mapping (depending on your destination class needs).
If you have large arbitrary data then you should just avoid using RestKit as it will only slow your performance.
We have a bunch of NSManagedObjects of various types.
Some of them have members that are NSSet's of other NSManagedObjects.
The problem is that I really need to override the hash and isEquals methods of the objects that are IN the set - but they are NSManagedObjects.
I'm having problems with getting multiple identical objects in the set.
As far as I can tell, since hash defaults to the object address - all objects are different. So I need to override hash and isEquals - but can't see any way to do it.
What we have is a bunch of stuff in the System, and more comes in via XML - sometimes repeats of the existing objects. When they are the same, I don't want dups added to the set.
As mentioned above by Wain, NSManagedObject documentation states that you must not override hash or isEqual:. So this means a stock NSSet does not do what you need.
Some of your options are:
Enumerate the NSSet contents to identify and remove duplicates
Write a factory method for your NSManagedObjects that will return the same object when given the same inputs
Fix the XML to not include duplicated objects
Unique the objects coming from the XML before they become NSManagedObjects
Modify the input XML to include a unique identifier that you can track, assuming the duplicated objects are exact duplicates
Implement your own NSSet-like collection class that performs a different uniquing test than hash and isEqual:
I was just trying to parse a JSON-Object which includes a 2-dimensional array.
Example:
{
"2dimarray": [
[{"key": "val"}, {"key": "val"}],
[{"key": "val"}, {"key": "val"}]
]
}
Assuming the contents of 2dimarray[x][y] are only of one type, I added the mapping:
[objectMapping mapKeyPath:#"2dimarray" toRelationship:#"2dimarray" withMapping: myMappingForIncludedObjects];
In the log RestKit tells me:
W restkit.object_mapping:RKObjectMappingOperation.m:438 WARNING: Detected a relationship mapping for a collection containing another collection. This is probably not what you want. Consider using a KVC collection operator (such as #unionOfArrays) to flatten your mappable collection.
But actually it is what I want. Basicly I assumed that the object mapper would fill my Objective-C property NSArray* 2dimarray with NSArray*s that include objects that are mapped with myMappingForIncludedObjects. Instead, each array is mapped (which fails, of course) with myMappingForIncludedObjects.
What am I doing wrong? Or better: What do I need to do to archive the behavior I expected?
I believe that the issue you cite is Blake explaining the problem, not a solution. I don't think RestKit is set up to handle the mapping that you describe (an array of arrays of objects). You can walk through an example of what he describes in the issue as well as looking at his commit, and you'll see that the introduced logic was aimed at detecting the problem and logging it for debugging purposes.
Right now I am using ArrayCollection. But I want to change that to Set as I want make sure do duplicate values come.
var addressList:ArrayCollection = new ArrayCollection();
One way is I can use Dictionary and store addresses as a key. And I can just use keys to iterate.
But I am looking for Java HashSet like implementation.
You want to download Polygonal Data Structures. The swc contains a HashSet. If you want Java-style template syntax for Flash, you should also check out Haxe.
The AS3 equivalent to HashMap or HashSet is the Dictionary class, and to a lesser extent, the Object class. Object keys are stored as strings, while with Dictionary the keys are objects. You can't have duplicate entries with either. Are you looking for a specific implementation other than that?