Having decided to explore Nodejs, i wanted to start with something like Rails that would be able to generate an MVC app from the database. While i haven't worked with Rails, i did work with the Rails inspired CakePHP, and liked it. So Sails.js was the equivalent in the Nodejs world.
On a side note, while Node is noted for its performance in handling I/O bound tasks, there are async frameworks in the Python world too like gevent and asyncio and uvloop, which can do the same, and there are some comparsions :
https://magic.io/blog/uvloop-blazing-fast-python-networking/
Development wise, i think i would prefer python over Javascript.
Anyways, on to sails :
So i installed node and sails 1.1 and fired the app with sails lift. Its nice to have some example models and setup running like sails has, so we can get started quickly.
Though sails does not generate CRUD from the database, there is a
sails-inverse-model module that does a basic CRUD generation. Haven't tested end to end tho.
I made some changes to the User model, added another model.
Then i wanted to point the default file-based database to my local mysql. Accordingly i toddled over to the config/datastores.js and made the necessary changes. Restarted sails and got a nasty shock ! There was a big stack trace about some auto-migration and some error about being unable to insert data. But i hadn't setup any migration. Seems that sails has a facility to apply to latest moel changes to the database, to keep the database in sync with the models. This is called migration, and is set to 'alter' by default in the config/models.js. This alter mode drops and recreates tables instead of altering them ! I fell this is a very dangerous behaviour, and should be been turned off by default.
So first thing, set migration to 'safe', or risk losing your data !
The next problem i faced was that my changes to the User model were not being reflected, and i was getting and error on account of that. I thought it might be some sort of caching. But restart or deleting the temp folder did not help either. Neither could i find any such issues reported on the internet. Finally, when looking at the files, i saw that there was a User.js~ backup file created by jedit, and this had the old User model that was getting picked up. Apparently the filter to load the files is too lenient, it will even allow a *.xml extension as a model.
In order to see where the files were being loaded, i created a syntax error in the model file. Sure enough, Sails complained about the error, and i saw from the error trace that it was being done in (
node_modules/sails/lib/hooks/moduleloader/index.js:304:18). Adding a [^~]$ at the end of the regex fixed the loading-backup-files issue at least.
Another issue was about having to restart sails after every change, which is really irritating. I saw options like forever, nodemon and sails-hook-autoreload. I tried the auto-reload-hook, but it seems to trigger the auto-migration again, so i removed it. I tried forever, one issue is that the stop does not work. Also, difficult to see logs, and if there are errors, it crashes. Still to check out.
Trying to get the hang of files. Did not like the actions approach, where each action lives in a separate file, rather than all in a controller. But the controller with methods approach is also supported. Tried using the ajax-form from parasails as in the examples. However, my form was not being rendered. Read about the client asset js file, and how we need to add one and register the page there, and write form validations. What about server-side validations, these would need to be repeated there too ? There should be a way to share them. And the default layout is updated to load all of these client files at once ! Why not include the required one in the particular view instead ?
Model objects are global, tho there seems to be a setting to control this. I like to know what i am importing.
Overall, sails seems to be doing too much implicitly, and if something is not working, finding and changing the behaviour takes a lot of time. I also wonder whether how all this affects performance. The Waterline ORM has its limitations like not fetching associations data. Also, what about all those facilities like default apis, one would need to know how to turn them off. I think i would prefer to go with something minimal like express, rather than sails.
On the positive side, sails comes with responsive ui and ready-to-go facilities.
It seems that sails comes with an auto-generator, and
just by defining a model, we can expose the model's api as json.