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can I invert the order the events creates by a rss trigger in my workflow ?
To invert the order of events created by an RSS trigger in your workflow, you would typically need to collect the events and then process them in reverse order. However, Pipedream triggers process and emit events individually as they are received, so there isn’t a built-in feature to reverse the order of events directly at the trigger level. If you need to process events in reverse order, you could consider storing the events in an array within a Pipedream workflow and then reversing that array. Here’s a basic example of how you could do this using a Pipedream workflow with Node.js code steps: 1. Use an RSS trigger to initiate the workflow when new items are found. 2. Store the events in a temporary array or data store. 3. Once you have collected all the events you want to process, use a code step to reverse the order of the array. 4. Process the reversed array as needed. Here’s a simple example of a code step that could reverse an array of events: ```
export default defineComponent({ async run({ steps, $ }) { // Assume events is an array of events you’ve collected const events = steps.previous_step.result; // Reverse the order of the events const reversedEvents = events.reverse(); // Now you can process reversedEvents as needed for (const event of reversedEvents) { // Process each event } // Optionally, return the reversed array return reversedEvents; }, });
if my trigger emits three events at time X1, X2, X3, it processes before X3 and then the others, I want to invert the process order
To process events in reverse order, you can’t directly invert the order of events as they are emitted by the trigger because Pipedream processes each event sequentially as it comes in. However, you can achieve the desired result by storing the events temporarily and then processing them in reverse order. Here’s an example of how you might write a Pipedream workflow to collect events and then process them in reverse: ```
import { axios } from “@pipedream/platform”; export default defineComponent({ props: { rss: { type: “app”, app: “rss”, }, data: { type: “data_store”, }, }, async run({ steps, $ }) { // Retrieve the stored events array, or initialize it if it doesn’t exist let events = (await this.data.get(“events”)) || []; // Add the new event from the trigger to the start of the array events.unshift(steps.trigger.event); // Store the updated events array await this.data.set(“events”, events); // Check if we’ve collected all events we want to process // For example, if we’re waiting for 3 events if (events.length === 3) { // Reverse the events array events = events.reverse(); // Process the events in reverse order for (const event of events) { // Process each event // For example, making an HTTP request with the event data // await axios($, { method: “POST”, url: “https://example.com/api”, data: event }); // Log the event or take other actions as needed console.log(event); } // Clear the events array after processing await this.data.set(“events”, []); } // Optionally, return the reversed array or a message return events.length === 3 ? “Processed events in reverse order” : “Event stored, awaiting more events”; }, });
are you familiar with Node.js? All of our triggers (called event sources) are available in our GitHub repo. You can see the RSS source here. If you’d like, you can publish a custom version of that source that reverses the order of items to your own account. See more about working with custom event sources here.