Adding data to the database using Portable classes

Anvil Q&A
1

Hello dear Forumers,

I created Client module with Portable classes

Inside that class put function which adding data to the database - same code which we’re usually putting to the server and calling by anvil.server.call.

Then I importing that Portable Class from Client Module to the Client Form and calling that function as usual we calling function of class

Speed of adding data to the Anvil database is fantactic - instant

but… security

How can I sucure my codes on Client side? on Client Module and Form?
Any thought?

2

If your data tables are accessible to the client, you cannot secure them. Security requires they only be accessible on the server. You can’t avoid the server call and maintain security.

Your portable classes could recognize whether they’re on the client or server and do something different in each situation. That at least would make it transparent to your client code. Something like:

from anvil import is_server_side

def save (self):
    if is_server_side():
        app_tables.table.update(whatever)
    else:
        anvil.server.call('update_object', self)
1 Like
3

Thank you very much Jay

This mean I cannot avoid server side calls

Sad

I thought I could restrict access to the Client module where I putted function which writes to the database

4

You have three access levels for data tables. No client access, client read access, or client read-write access. Any level of client access is available to the entire client. Any sufficiently motivated hacker could write their own client code to perform operations on the data table that you didn’t intend, if the client has write access.

The same holds true for server calls, too. Any sufficiently motivated hacker can cause the client to call the server calls with data you didn’t intend, so the server calls need to check to make sure the update coming from the client makes sense.

5

did you see this post: Partially-writable Data Table rows ?

looks like you can have restrictions(capabilities) on client writable rows

6

That’s more of a row level filter. It helps if there are no bad updates that can be put into those rows (e.g. no invalid combinations of data, no restrictions on who can update certain fields, etc). Otherwise, you still have logic in the client that can be circumvented by hackers.

If you do have a data table where the user can put any data in any field and it’s okay, then a client-writeable view would be safe.

Edit: Sorry, the above was responding only to the client-writeable view portion of the linked post. The full approach that was given in that linked post is perfectly fine for the OP’s needs, although it only hides the server call, not eliminate it.

1 Like
7

See Views.

8

“Server Modules can return views on a Data Table to client code, with extra permissions or restrictions.”

Again we need server code

9

Guys,

İ think İ found solution to write down data to the Avil server fast

  1. Create duplicate table in Database. - give full permission to Client code

  2. Write data from Client to that Duplicated table - function on Client side

  3. Copy data from Duplicated table to the Main table (Which is restricted to write from Client) - Server function

  4. Delete data in Duplicated table - same Server function

Write down time decrease from 30 sec approx to 7-8 seconds!! Which is acceptible

Executed by one Client function and on Anvil.server.call with one button click

What do you think?

10

30 / 7 seconds to write to the database?
That’s a huge time!

How much data are you saving?
Why is it taking so long?

I never had an app that needed more than half second to save.

Reading can be slow, because it can require accessing tons of rows, from multiple tables and reorganizing the whole thing before sending it to the client. But in my experience the amount of data that the client changes or adds and needs to be saved is always so small that can be saved in real time.

11

User inputs of financial reports
All anvil. Server. Call functions are very slow

12

How many millions of numbers do users type between two saves :slight_smile: ?

If the input comes from a form data entry rather than a sensor, how is it possible that you have megabytes of data to save? Any user can’t possibly type that much?

13

It it just several numbers))
Many forms with couple of lines inputs

14

Calling a server function and passing several numbers to save them to the database shouldn’t take longer than half a second (for me in the US, if you are closer to the UK it should be faster)

I’m sure if it takes 30 seconds there is something going on that is wasting 99% of the time. And adding one more table and copying stuff from table to table, it can only slow down (but I don’t know the details, so perhaps I’m completely wrong).

15

I want you could be right, but believe me, anvil.server.calls slow down every Form it’s included. My application is ready, and I’m afraid to go into the production and present it - users will not accept its slow performance.
And next thing I should optimize - it is PDF creation. Here I have to wait around one minute to get download Two-page PDF.
But the most slow performance I face with Dashboards - even I decided to postpone including them to the application))

16

Well… I can’t comment on your app, because I haven’t seen it. But I can comment on my apps. There are cases where I need to wait a few seconds to populate the form, because the server needs to dig and find the data and do some calculation with it before returning it to the form. But once the form is populated, I have never needed more than half a second to save.

I have hundreds of apps, and some can be slow to start because they are large, some forms can be slow to populate because they need to do complex calculation before completing the rendering, but saving from the from to the server has always been in real time, never more than half a second.

1 Like
17

@stefano.menci

This is excellent job done !
Thank you very much and I try to fully understand this )

18

You might want to start a new thread asking for optimization advice, showing example code that is slow. It does seem that your results are significantly slower than others are seeing.

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