MOBILE-4547 blog: Support offline blog

[alfonso-salces]

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[dpalou]

This code is not enough, we also want to save the data if the server is down. This is how the app works in all other cases. This problem also happens when creating a new entry.

Also, if the user is editing an offline entry but he's online when the Save button is pressed you will create the entry twice, because this function will send the data to the server (creating the entry) but the app will still have the offline data that will be sent later when synchronised. This can be fixed with the "forceOffline" parameter I tell you below.

If you look at this calendar code you'll see that the "storeOffline" function is called in 3 cases:

1. When the user is offline.
2. If the "forceOffline" parameter is true. You should use this when the user is editing an offline entry, that way you will save the data in offline even if the user is online now, and the sync process will be the one to send the entry to the server. In order for this to work properly, the index page should try to synchronize the data when opened as we do in many other places, I'll leave another comment about this.
3. If a WS call returns an error and it's not a "WebService error" (function CoreUtils.isWebServiceError). The WS calls can return errors like the ones telling you don't have permissions to do the action, in that case we don't want to store the data in offline because the user cannot perform the action. But if the error is not a WebService error, e.g. is an error 500, or a timeout or something like this we store the data to try again later.

This is just a personal opinion, but I usually prefer putting this logic to check network, erros and so on in a service instead of in the page (like calendar does). But if you prefer to leave it in the page it's ok for now since this is the only place creating entries.