Best way to reload data when using Node.js WebSocketServer?

[mhkeller]

Following the Server-only via WebSocketServer() and Node.js docs, I am loading in an arrow file on the node server using host.host_table("table_one", table);. I want to be able to overwrite this data table and replace it with a new one. What's the best way to do that?

I don't see any docs for the WebSocketServer api but looking at the source code, I see it has an eject_table method which I can use like this:

host.eject_table('table_one');
host.host_table('table_one', table);

This seems to work and ejecting a table that does not exist doesn't throw an error. Is this the best pattern?

Note: The only issue I'm running into this is on the client where if the schema of my first file contains a subset of fields on the file that replaces it, the perspective viewer will not display those additional columns. I think I can play around with the perspective viewer, though, and have it reset its filters... This seems to have worked to reset the state on the client:

await elem.load(server_table);
await elem.reset();

[mhkeller]

I'm not sure if I have this right. The docs have a few references to clearing and deleting but I'm not able to glean what all of the proper reciprocal methods are. Here's what I have so far:

On the server

const { WebSocketServer, table } = require("@finos/perspective");

const host = new WebSocketServer({ assets: [__dirname], port: 8080 });

const table_id = 'foo';
// Clean up any existing table with this id
host.eject_table(table_id);

// Read in the arrow file
const file = readFileSync('data.arrow');
// Create the table
await table(file);
// Host the table
host.host_table(viewId, t)

On the client

// Do I need a clear here at the beginning that mirrors host.eject_table?
const server_table = await websocket.open_table(table_id);
elem.load(server_table);
// Reset the config with these two lines. Not sure why both seem necessary
elem.restore({})
elem.reset();

This seems to give me the right behavior but throws an error if any columns are dropped between calls to this lifecycle. Here's an example:

I tried putting the calls to .restore and .reset in a try...catch but I still get the error.

My two main questions are:

1. Do I need to clear the client before calling elem.load again?
2. Is there a better way of clearing the config to the default?