beforeScriptListener custom extension

  • Hi,

    We are trying to migrate to v3 from v2.11 and there is one piece that doesn't quite fit.

    We have a custom extension that allow us to run some queries internally and return the data.
    On version v2 we have the following jsreport.config.ts

    module.exports = {
        name: "dataLoader",
        main: "index.js",
        dependencies: ["templates", "data", "scripts"]

    It seems that something change on v3 and dependencies is not longer there, not quite sure if we need to do something to adapt that.

    The main issue I think is on the actual extension code, we had

    reporter.initializeListeners.add("dataLoader", async () => {
                { after: "assets" },
                async (scriptDef, req, done) => {

    We use the beforeScriptListeners. It's not documented but it does what we need.
    To add some context:
    We have a jsreport script that adds some queries to = [QUERIES]

    Then on our extension we check the, we run the queries internally and we store the results on[tableName]

    If we try run the code as we have it on v3 the first error comes loading jsreport trying to access to beforeScriptListeners because it doesn't exist on the reporter. If we switch this to beforeRenderListeners when we reach the code it doesn't contain the data we need, my guess is because it actually run before the render and not before the scripts so at that point our script that set the queries on hasn't even run yet.

    What can we do? How we can run our extension to being able to capture that data?


  • Some documentation:

    Since v3, we split extension's code to the main part running in the main thread and worker part running in the safe worker thread. You just need to register beforeScriptListeners in the worker part and that should be all.

    This could be a simple example for you

  • Awesome, it worked like a charm.

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