JavaScript callback

Client to server

To call backend from JavaScript pantra defines method: processCall(oid, func_name, *args). Called function should be allowed by allow_call().

• oid - is unique node OID of any node in execution context. There is simple JS API to get OID:

  • OID.get(node) - get node OID

  • OID.node(oid) - get node by OID

  Otherwise, get node ID with pythonic expression node.oid.

• ‘func_name` - function defined in local Python script

• args - all simple types are serializable including lists and dicts

Example:

<script type="text/javascript" >
function go(oid) {
    let data = {
        a: 1,
        b: 2,
        c: 3
    };

    processCall(oid, "call_from_client", data);
}
</script>
<button onclick="go(`{ctx.oid}`)">Call from client</button>
<python>
def init():
    ctx.allow_call('call_from_client')

def call_from_client(data):
    session.log(data)
</python>

Server to client

To call JavaScript method from Python script use call() method. All simple types are serializable including lists and dicts.

Example:

<script type="text/javascript">
    function callFromServer(data) {
        console.log(data);
    }
</script>
<button on:click="go">Call from server</button>
<python>
def go(node):
    data = {
        'hello': 'from server',
    }
    session.call("callFromServer", data)
</python>