Gson and the argonauts - problem converting javascript array, to json string, to java pojo using gson. Trying to get my structures correct
Here is my json string, that I am acessing in java:
json =
[
{"id":"123456","Data":"skill2","dmlcrud":false},
{"id":"123456","Data":"skill3","dmlcrud":true},
{"id":"123456","Data":"skill14","dmlcrud":true},
{"id":"123321","Data":"skill1","dmlcrud":false},
{"id":"123321","Data":"skill14","dmlcrud":false}
]
I now want to put it in a collection so ideally/theoretically I would want to do:
List<Person> personList = new Gson().fromJson(json, Person.class);
and personList.size() would = 5. I would then loop through personList and preform my relevant actions.
However, my understanding is that I would need to create a container class, which itself contains the person list ? So instead of (public getters/setters removed for brevity, probably syntax errror in there aswell).
Class Person {
private integer id;
private String Data;
private Boolean dmlCrud ;
}
I would actually need something like ?
Class container{
List<Person> personList;
static class Person {
private integer id;
private String Data;
private Boolean dmlCrud ;
}
}
However I would then need to alter the javascript json to be somethign different aswell ? Which seems rather probl开发者_开发知识库ematic as am I creating the json string from a javascript array, using JSON.stringifier.
Any help gratefully received.
EDIT
the solution I used was to add
public List<Person> personList;
to the person class and alter the json object so that it was
{ "personList" :
[
{"id":"123456","Data":"skill2","dmlcrud":false},
{"id":"123456","Data":"skill3","dmlcrud":true},
{"id":"123456","Data":"skill14","dmlcrud":true},
{"id":"123321","Data":"skill1","dmlcrud":false},
{"id":"123321","Data":"skill14","dmlcrud":false}
]
}
the gson call can then be
Person person = new Gson().fromJson(json, Person.class);
and the data accessed in a list like so
List<Person> personList = person.getPersonList();
EDIT 2
A second, better, solution is to use this json array
[
{"id":"123456","Data":"skill2","dmlcrud":false},
{"id":"123456","Data":"skill3","dmlcrud":true},
{"id":"123456","Data":"skill14","dmlcrud":true},
{"id":"123321","Data":"skill1","dmlcrud":false},
{"id":"123321","Data":"skill14","dmlcrud":false}
]
and then use
Type listType = new TypeToken<List<SkillsGsonTO>>() {}.getType();
List<Person> personList = new Gson().fromJson(json,listType);
Person person1 = personList.get(0);
where the original class is used
Class Person {
private integer id;
private String Data;
private Boolean dmlCrud ;
}
You could use a Container class but this only makes sense if you need to ship additional properties on the person list. If this is not the case, you could convert to a java.util.List as well. I think you need to specify the "name" of the list property as a root element in your JSON string. So for instance if you're domain object is a List of Person objects, than your JSON root element is: "persons" or "personList". So you're JSON could look something like:
"persons" : {[
{"id":"123456","Data":"skill2","dmlcrud":false},
{"id":"123456","Data":"skill3","dmlcrud":true},
{"id":"123456","Data":"skill14","dmlcrud":true},
{"id":"123321","Data":"skill1","dmlcrud":false},
{"id":"123321","Data":"skill14","dmlcrud":false}
]}
I could be a little bit off with the syntax, but it should be something similar to this. So to summarize:
In your case you can leave you're Person class untouched and gson should be able to create the List persons for you from the JSON string I suggested.
From the Gson API docs: If the object that your are deserializing is a ParameterizedType (i.e. contains at least one type parameter and may be an array) then you must use the fromJson(String, Type) method. Here is an example for deserialing a ParameterizedType:
Type listType = new TypeToken<List<String>>() {}.getType();
Gson gson = new Gson();
List<String> target2 = gson.fromJson(json, listType);
So in your case it would be:
Type listType = new TypeToken<List<Person>>() {}.getType();
List<Person> persons = new Gson().fromJson(json, listType);
where json is your json string obviously
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