[aerogear-dev] [aerogear-android] DataManager API inconsistency + solution

[Tadeas Kriz]

Hey everyone,

I’ve been recently going through the DataManager API in aerogear-android. In this email, I’d like to suggest addiction of two method (or possibly three) into the `Store<T>` interface. These would be:

```java
/**
 * If store is open, it can be read or written to.
 */
boolean isOpen();

/**
 * Opens store in current thread (blocking).
 */
Store<T> open();

/**
 * Opens store in background thread and then callback#onSuccess is called.
 */
void open(Callback<Store<T>> callback);
```

>From my point of view, this makes sense to be in the `Store<T>` so I can switch between stores easily during development with no need to change other code. Also, if `read` or `write` operations are done with closed store, there are two possible workflows. First one is, that I’d fail and throw an exception. Second (and for me a preferred one) is, that all those methods would internally check if the store is open and if not, they’d call the `open` method. This also leads me to another API change for `Store<T>`.

```java
/**
 * Reads all the data from the underlying storage system asynchronously.
 */
void readAll(Callback<Collection<T>> callback);

/**
 * Reads a specific object/record from the underlying storage system asynchronously.
 */
void read(Serializable id, Callback<T> callback);

/**
 * Search for objects/records from the underlying storage system asynchronously.
 */
void readWithFilter(ReadFilter filter, Callback<List<T>> callback);

/**
 * Saves the given object in the underlying storage system asynchronously.
 */
void save(T item, Callback<Void> callback);

/**
 * Resets the entire storage system asynchronously.
 */
void reset(Callback<Void> callback);

/**
 * Removes a specific object/record from the underlying storage system asynchronously.
 */
void remove(Serializable id, Callback<Void> callback);

/**
 * Checks if the storage system contains no stored elements asynchronously.
 */
void isEmpty(Callback<Boolean> callback);
```

That’s right, async methods for easy access to the storage from background thread, without the pain of writing it myself (for example, it makes no sense if I want to just call `store.save(..)` and I’d have to write all the `AsyncTask` boilerplate).

So, what do you think?

PS: You can find the whole text with highlighted syntax here: 

—
Tadeas Kriz
tkriz at redhat.com