Need to compare to the value of yesterdays run

[lubeda]

I am really new to n8n as you will see. So here is my situation.
I query a rest api and get an array as answer. The next day i will do the same but want to compare the result to the day before to see if there are some new values.

The Rest-API is: https://awtrix.blueforcer.de/app?type=getAppList

So when there is a new entry in the array i will get an message. But how to compare to the result of yesterday?

Greeting from Germany #coronasucks

[jan]

Welcome to the community @lubeda!

To save the data you can use static-data if it is not large. Probably best you do not save the whole array only some kind of ID for each. That makes it then also easier to compare later to filter out the ones you did already process.

Here some information about static-data:

How to pick the latest item (row) added to an airtable table?

Ok in the latest n8n version (0.25.1) the bug got now fixed. Also, do the function nodes now have access to the static data. Here a basic counter-example: Be aware that the static data does not get persisted when testing via the Editor-UI. Only if it is in production mode will the static data be persisted and it will count up.

Code | n8n Docs

Here also some other ways to store data:

Storing and loading content from filesystem

Hello, i want to scrape a knowledge base and send myself new posts. For this I plan to store the article IDs somwhere in n8n and then filter them out in subsecuent executions. Can this be done?

For the comparison, you can then use a Function-Node. With it, you can then use for example a JavaScript filter function on the items or reference the data in an IF-Node and filter there. Not sure if you have JavaScript experience. If yes it should not be too hard, if you do not have, then it is probably harder. But here an example:

How to filter json data using function node?

Welcome to the community @suparman_aguuus! There are multiple ways to do that. Really depends on what you want to do with the data afterward and what else you have planned. One way would be to move the data you have underneath data into different items and then filter via an IF-Node. Another way would be to directly filter the data with the help of a Function-Node and leave it all in the first item underneath data. Here the workflow for both:

Apart from that should you find multiple examples if you search here in the forum for “filter”.

Hope that helps! Have fun!

Greetings back from Berlin!