Solving the Golang MySQL Query Issue: How to Properly Append Data into Structs

Discover how to fix the issue of appending query data into structs in `Golang` when working with MySQL. Follow our step-by-step guide for success!
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Solving the Golang MySQL Query Issue: How to Properly Append Data into Structs

When working with databases, it’s not uncommon to run into various issues, especially when dealing with querying data and parsing it into structs. A common scenario that developers encounter is the inability to append query results into a slice of structs in Go (or Golang). If you’ve faced a situation similar to the following, you’re in the right place!

The Problem

You’ve executed a MySQL query expecting to retrieve data into a struct, but for some reason, your struct list remains empty. While running the same query directly in MySQL Workbench returns the expected results, the Golang code fails to provide any output.

Here's a snippet of what the issue looks like:

[[See Video to Reveal this Text or Code Snippet]]

TodoUserDTO Structure

The struct in question is defined like this:

[[See Video to Reveal this Text or Code Snippet]]

As we can see, the intention is to map the data from the SQL query results directly into a slice of TodoUserDTO structs. So, what’s going wrong?

Understanding the Solution

The root cause of the issue lies in the SQL query itself. Instead of using the actual column names, the current query uses the string literals 'description' and 'is_done'. This means you are not actually querying the columns from the tasks table but rather returning those strings as results. Let’s break down how to fix it.

Step 1: Correct the SQL Query

Replace the current query with one that uses actual column names instead of string literals. Your new SQL query should look like this:

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Run the Updated Code

After updating the query, you can run the code again. The corrected query will now retrieve the actual values from the tasks table and appropriately map them to the fields of your TodoUserDTO struct.

Step 3: Check for Errors in Data Retrieval

Make sure to check for any errors while scanning the results to avoid silent failures. You can modify the code slightly to handle scan errors:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

By ensuring that your SQL queries utilize the correct column names instead of string literals, you can solve the issue of appending query data into a struct list in Golang. Remember to always check your queries and handle potential errors properly to prevent issues in data retrieval. Happy coding!