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Learn the best methods to `append data` into a CSV file using ChoETL while processing multiple JSON files efficiently.
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How to Append to the Same CSV File with ChoETL

When working with data, especially in formats like JSON and CSV, one common issue developers encounter is the need to append data to an existing CSV file without overwriting it. If you’ve been struggling with this while using ChoETL, you're not alone.

In this guide, we'll discuss how to properly append multiple JSON files’ data into a single CSV file using ChoETL’s APIs. We'll explore various methods to ensure that your data is not lost and is structured correctly in the resulting CSV.

The Problem

Consider that you have multiple JSON files that need to be converted and consolidated into a single CSV file. You might have started with code to parse these JSON files and write to a CSV, only to find that the CSV file is being overwritten with each iteration—it only contains the last JSON file's data. This is frustrating, as you likely want all the data from those JSON files to appear in the CSV.

For example, with three JSON files in your input, you would want the output CSV to look like this:

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Instead, you are getting only the last entry. Let’s solve this issue.

Solution Approaches

There are several ways to append data to a CSV file using ChoETL. Here are three different options you can implement in your project:

Option 1: Update Method Signature

One simple way to handle multiple JSON files is by modifying the method signature to accept an enumerable collection of JSON input files. Here’s how you can do it:

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Key Changes: This version of the JsonToCsv method will read each JSON file in the collection and append its data to the provided CSV file.

Option 2: Use FileStream with Append Option

Another method is utilizing FileStream with the Append option. This allows you to open the file and write to it without overwriting existing data.

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Purpose of this Method: This approach helps handle the CSV format efficiently while ensuring that data remains structured and complete.

Option 3: Conditional File Mode

You could switch between create and append options using a condition. This is useful if your logic needs flexibility for different execution contexts:

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Usage: This approach allows dynamic file handling based on your program’s needs, streamlining file access operations.

Conclusion

Dealing with data management can be tricky, especially when it comes to file handling. By utilizing the methods discussed above, you can easily parse multiple JSON files and append their data to a single CSV file using ChoETL. Remember to choose the method that best fits your requirements and context.

If you have any questions or thoughts, feel free to reach out. Happy coding!