This is more of a question on design approach. I have an application which has the following details:
UI in Angular
UI uses an api which is in Node/Express
Database is just a JSON file for now.
I want to move to mongoDb from the JSON file. What I'd like is, whenever anyone uses the UI to make changes to the database, I'd like to review the changes before they are updated in the database. what is the best way to achieve this?
This was easier for me with the JSON file because I was creating a pull request on git where I would review all the changes and then update.
Things that I have thought:
Let the UI write to a separate clone collection(table) and then review them and update the main collection accordingly. Not sure if this is the right way to do it.
Are you yourself wanting to review changes, or wanting an end user to review before saving? If it's you, you have a few options:
You can create a mongodb collection of pending objects that will get moved to a different collection once they're approved. This is OK, but not great because you'll end up shuttling objects around and it's probably more reasonable to use a flag to do aggregate grouping instead of collection-based delineation
You can simply use a property on an object as a flag and send objects that are pending review to your db with that flag enabled (using some property like true, 1, or another way of saying "this is true/on/enabled etc.")
If you want an end-user to be able to save, you can use mongoose hooks/middleware to fire off validators or whatever you want and return a response with meaningful data back to your angular UI. From there, you can have a user 'review' what they're saving. This doesn't persist or get saved, it's only saved once they send everything back up again (if that's how you choose to build the save process).
Related
I am working on an API for my first web app, a scheduling system, with Django on the back end.
Shifts are sent to the front end in a single JSON object (schedule), that contains shift objects. This object can then be modified by the front end and sent back to have the server update the database according to any changes in the JSON object.
My question: is it better to use "marker" properties, such as {... "delete": true...} and {... "new": true...} within the shift objects to let the server know what has changed, or should the back end figure it out on its own by comparing the incoming data to existing data?
The first option seems to me to allow for fewer database queries, while the second option seems more robust (i.e. it does not depend on the front end to properly tag its changes).
Also, as this is my first attempt at web dev, any related recommendations or criticisms are encouraged.
Here's my question: How might I try to get rid of the 'skipping precaching' and cache everything that comes in from https://laoadventist.info/beta/r as the precache list?
Also, is it correct for me to set precache="https://laoadventist.info/beta/r" or should I be setting that to a function that grabs the data and returns it instead?
Skipping precaching: Cannot read property 'concat' of null
comes out on the console when using My Polymer App
<platinum-sw-cache default-cache-strategy="fastest" cache-config-file="cache-config.json" precache="https://laoadventist.info/beta/r">
I am assuming correctly I can precahce a URL like this, right?
I am trying to load a json result from laravel 5.1 to set what my precache should be... I know it's not the most elegant, but I'm new to Polymer, cache, service workers, etc, and using this app as a learning opportunity. It'll be a bit different at the end of the day, but for now I just want to load everything. :)
I want to precache all of the data so that a user can fully utilize this app when offline (though later I'll set it up so that they don't have to precache loads and loads of json requests, only the ones they want, like per book - but that's for later).
If you have a array of resource URLs that you want precached, the cleanest way to specify them is to use the cacheConfigFile option and to point to a JSON file that contains your array as its precache property. Take a look at the example in the docs for cacheConfigFile: https://elements.polymer-project.org/elements/platinum-sw?active=platinum-sw-cache
You shouldn't have to use the precache attribute on the element if you're using cacheConfigFile.
It sounds like you're using Polymer Starter Kit, and that will create the JSON config file and populate it for you with an array corresponding to your local resources. But if you'd like to specify additional resources to be precached, you can modify the build process to append those URLs to the auto-generated list.
The reason you're seeing that error is because you're pointing to a JSON config file that is effectively empty, and is just meant for the development environment.
Is there common design pattern for dispatching deleted objects to the requestor (client of the API)?
Challenges we are having:
When object is deleted on the API completely, client will not know
that object is gone and will keep it locally (as API only shows objects changed after the certain date)
If we enable object's property to show that is deleted (ex. "deleted = TRUE") then
eventually number of objects in the API grows and slows down the transfer rate.
Another option we looking into is to have separate Endpoints on the API to show list of deleted objects only (is this the pattern that anyone uses?).
I'm looking for most "RESTful way" to delete local objects.
The way I handle it is a variation on your #1: each item has a last updated field in the database, and if something is deleted, I make an entry in another table of deleted items, and it's updated value is when it was deleted.
The client makes a request asking for "changes since X" which is their own locally stored last updated value...it returns new data, and an array of deleted items. Then on the client I purge those values
Stale data is always a problem with client/server applications. If clients loads some data, then some object is deleted on the server, and then client sends a DELETE request, the RESTFul thing to do would be to return a 404, which indicated "not found". If the client knows that if it sends a DELETE, and gets a 404, the resource was deleting from underneath...
What if you think of your resource not as a list, but rather as a changeset?
Eg. changesets what you have in git or SVN.
This way, there's always a "head" version, and the client always has some version, and the resource is the change between client's last and head.
That way you can apply whatever you've learned by examining/using version control systems.
If you need anything more complex, the science behind is called Operational Transformation (OT) - http://en.wikipedia.org/wiki/Operational_transformation
I am creating a dashboard application in which i show information about the servers. I have a Servlet called "poller.java" that will collect information from the servers and send it back to a client.jsp file. In the client.jsp , i make AJAX calls every 2 minutes to call the poller.java servlet in order to get information about the servers.
The client.jsp file shows information in the form of a table like
server1 info
server 2 info
Now, i want to add one more functionality. when the user clicks on the server1, I should show a separate page (call it server1.jsp) containing the time stamps in which the AJAX call was made by calling.jsp and the server information that was retrieved. This information is available in my calling.jsp page. But, how do i show it in the next page.
Initially, i thought of writing to a file and then retrieving it in my server1.jsp file. But, I dont think it is a good approach. I am sure i am missing a much simpler way to do this. Can someone help me ?
You should name your servlet Poller.java not poller.java. Classes should always start with an uppercase. You can implement your servlet to forward to a different page for example if sombody clicks to server1 then the servlet will forward to server1.jsp. Have a look at RequestDispatcher for this. Passing information between request's should be done by request attributes. if you need to retain the information over several request you could think about using session.
In the .NET world, we use SessionState to maintain data that must persist between requests. Surely there's something similar for JSP? (The session object, perhaps.)
If you can't use session state in a servelet, you're going to have to fall back on a physical backing store. I'd use a database, or a known standard file format (like XML). Avoid home-brew file formats that require you to write your own parser.
I'm using CouchDB and I have a situation where there are a bunch of documents keyed on user ids. I would like to be able to send a single query to update a particular field in all these documents. For example when a notification comes in, I'd like each user document to be updated with it by passing in the list of users to whom the notification applies and the notification message.
Sadly the _update handlers in CouchDB currently only support a single document at a time, so it's not possible to use an _update handler on multiple documents. For this, you'd need to build a small "proxy," server-side script that would receive the request and send individual _update handler requests one per document. Not ideal, but until there's a patch to allow bulk update handlers to be built, this is the way to go.
I've requested a _bulk_update handler (or similar) be added to a future version of CouchDB...as I'd like the feature as well. :)
https://issues.apache.org/jira/browse/COUCHDB-1303
I'd read _changes (probably apply a filter) and then execute the HTTP queries needed.
Keep in mind that you'll need to fetch the document, before updating it.