Design patterns - Data to object

Question

Suppose I have some data in a file or maybe database. It could be JSON, XML, YAML, CSV, String[], etc.

I'd like to create a model object with this data. For example:

Data:

{
    "name": "John Doe",
    "age": "30"
}

Model (Pseudocode):

class Person {
    Person(name, age) {
        this.name = name;
        this.age = age;
    }
    // business logic
}

Some code that creates Person objects from JSON data (Pseudocode):

peopleArray = [];
recordSet = aJSONReader.read('file');
for (recordSet as r) {
    peopleArray.add(new Person(r[0], r[1]));
}

What would you use to build model objects from given data? In my example I'd start supporting JSON. What if I'd like to change it or support new data formats? How do I decouple this code? Which design pattern fit here?

Answer 1

Use the strategy pattern (see here). You want to provide different methods to parse data. A method would parse JSON, another method would parse XML and another method would read a database. Each method can be seen as a strategy to parse data and generate data objects.

Create a common interface, let's say IDataObjectParser with a single method like public List<DataObject> parse(). Each parser would implement this interface. Then you can exchange the parser whenever you want, e.g. during runtime or according to a configuration file.