Support changing dataType for a binding in v4

[ejizba]

v3 function.json content:

{
    "name": "myQueueItem",
    "type": "queueTrigger",
    "direction": "in",
    "queueName": "helloworldqueue",
    "connection": "storage_APPSETTING",
    "dataType": "binary"
}

v3 index.js content:

module.exports = async function (context, myQueueItem) {
    context.log('JavaScript queue trigger function processed work item', myQueueItem);
};

In v3 the type of myQueueItem changes based on the value of dataType. If you set dataType to binary, myQueueItem will be a Buffer. Otherwise, myQueueItem will either be a string or possibly a parsed object if the string was JSON.

In v4, we don't allow users to change myQueueItem to a Buffer type, which we should. This does not apply to http triggers, but probably applies to several other triggers/bindings other than storage queue.

[vsantele]

Is there any news on this issue? Or a way to help fix it?

[ejizba]

No updates, but this is still planned to be fixed before we GA. For a workaround, either use the v3 model or use generics:

import { app, InvocationContext, trigger } from "@azure/functions";

export async function storageQueueTrigger1(queueItem: unknown, context: InvocationContext): Promise<void> {
    context.log(`Is it a buffer? ${Buffer.isBuffer(queueItem)}`);
}

app.generic('storageQueueTrigger1', {
    trigger: trigger.generic({
        type: 'queueTrigger',
        queueName: 'testqueue',
        connection: 'storage_APPSETTING',
        dataType: 'binary'
    }),
    handler: storageQueueTrigger1
});