Tracking updates and changes in JSON data is crucial for many applications, from monitoring API updates to version control. For instance, imagine wanting to keep up with the latest releases of Minecraft versions by comparing JSON metadata. Directly comparing raw JSON strings can be cumbersome and inefficient, especially when dealing with complex structures. This article explores how to effectively Compare JsoN data within n8n, a powerful workflow automation platform, to streamline version tracking and identify new entries.
Many users, like in the example of tracking Minecraft versions, attempt direct JSON comparison in n8n and encounter difficulties. Often, simple comparison methods yield outputs indicating completely different datasets (“In A only” and “In B only”) even when the changes are subtle. This is because direct string or object comparison fails to account for the structure and intended logic of comparing lists of items within JSON.
To overcome this, n8n offers a robust solution using the Item Lists node in conjunction with the Compare Items mode. This approach allows for intelligent comparison of JSON arrays, identifying differences based on a specified key property. Instead of just seeing “different JSON,” you can pinpoint exactly what’s new or changed.
Here’s a breakdown of how to implement an efficient JSON comparison workflow in n8n for version tracking:
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Fetch New JSON Data: Begin your workflow with an HTTP Request node to retrieve the latest JSON data from your source. In the Minecraft example, this would be the endpoint providing version information.
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Prepare Data (If Necessary): Depending on your data source and how you are storing the previous version, you might need a Set node or Function node to format or prepare your current and previous JSON datasets to be in a consistent array format for comparison. For simplicity, let’s assume you have two JSON arrays ready for comparison: one representing the old data (A) and one representing the new data (B).
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Utilize the Item Lists Node: This is the core of the solution. Add an Item Lists node to your workflow. Configure it as follows:
- Mode: Select “Compare Items.”
- JSON/RAW Parameters: Choose “Use for Items Lists” for both List 1 and List 2.
- List 1 Items: Input your “old” JSON data (List A). This could come from a previous execution, a stored JSON file, or any source holding the baseline data.
- List 2 Items: Input your “new” JSON data (List B) obtained from the HTTP Request node.
- Property to Compare On: Crucially, specify the property within your JSON objects that uniquely identifies each item. In the Minecraft version example, the
"id"field is the ideal choice as it uniquely represents each version. Enter"id"in this field.
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Analyze the Output: The Item Lists node in “Compare Items” mode provides three outputs:
- In A only: Items present only in the “old” JSON (List A).
- In B only: Items present only in the “new” JSON (List B). This is where you’ll find the new entries – the new versions in the Minecraft example.
- In Both: Items present in both lists.
By examining the “In B only” output of the Item Lists node, you get a clean list of the new versions or entries that have been added since the last data retrieval. This method efficiently compares JSON arrays based on a key identifier, providing a practical solution for version tracking and identifying updates in your data.
In conclusion, for effective JSON comparison in n8n, especially for version tracking and identifying new entries in lists, the Item Lists node with “Compare Items” mode is the recommended approach. By specifying a key property for comparison, you can accurately pinpoint the differences between JSON datasets and automate the process of tracking updates, like new Minecraft versions, with ease and precision.
