Question

I am working on a web application which is based on spring MVC. We have various screens for adding different domain components(eg. Account details, Employee details etc). I need to implement an upload feature for each of these domain components i.e. to upload Account, upload employee details etc which will be provided in a csv file (open the file, parse its contents, validate and then persist).

My question is, which design pattern should i consider to implement such a requirement so that upload (open the file, parse its contents, validate and then persist) feature becomes generic. I was thinking about using the template design pattern. Template Pattern

Any suggestions,pointers,links would be highly appreciated.

Answer 1

A strategy pattern my be useful here for the uploader. The Uploader class would be a sort of container/manager class that would simply contain a parsing attribute and a persistance attribute. Both of these attributes would be defined as an abstract base class and would have multiple implementations. Even though you say it will always be csv and oracle, this approach would be future-proof and would also separate the parsing/verifying from the persistence code.

Here’s an example:

class Uploader
{
private:
    Parser parser_;
    Persistence persistence_;

    void upload() {
        parser_.read();
        parser_.parse();
        parser_.validate();
        persistence_.persist(parser_.getData());
    }

public:
    void setParser(Parser parser) {parser_ = parser;}
    void setPersister(Persistence persistence) {persistence_ = persistence;}
};

Class Parser
{
    abstract void read();
    abstract void parse();
    abstract void validate();
    abstract String getData();
};

class Persistence
{
    abstract persist(String data);
};

class CsvParser : public Parser
{
    // implement everything here
};

// more Parser implementations as needed

class DbPersistence : public Persistence
{
    // implement everything here
};

class NwPersistence : public Persistence
{
    // implement everything here
};

// more Persistence implementations as needed