Fixing Set Map String, dynamic Can't Be Assigned to Parameter Type Error in Flutter Firestore

Learn how to resolve the `Set Map String, dynamic ` can't be assigned to the parameter type 'Map String, dynamic ' error when writing data to Firestore in Flutter.
---

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Set Map String, dynamic ' can't be assigned to the parameter type 'Map String, dynamic error in Flutter when writing to Firestore

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Understanding and Resolving the Flutter Firestore Error

When working with Flutter and Firebase, you may encounter various errors that can hinder your app development. One common issue developers face is the error message: Set<Map<String, dynamic>> can't be assigned to the parameter type Map<String, dynamic>. This error typically occurs when you're trying to write a custom user model to Firestore using the toMap() function. Let's delve into why this error occurs and how to resolve it effectively.

The Problem: What Causes the Error?

You might have a custom user model similar to this:

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

You then try to use this method to save data to Firestore as follows:

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

However, this results in an error stating that a Set<Map<String, dynamic>> cannot be assigned to a parameter type of Map<String, dynamic>. This can be confusing, especially when your toMap() function appears to be correct.

What’s Happening Under the Hood

The crux of the error lies in the distinction between Set<Map<String, dynamic>> and Map<String, dynamic>. To clarify:

Set<Map<String, dynamic>> represents a collection of maps, which can look like this: { { 'test': 'msg' } }.

On the other hand, Map<String, dynamic> is an individual mapping of keys to values, such as {'test': 'msg'}.

Example:

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

The Solution: Correcting the Code

Original Code (Problematic):

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

Corrected Code:

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

By making this change, you are now correctly passing a Map<String, dynamic> to the set() method, aligning with the expected parameter type.

Conclusion

With clarity around the differentiation between Set<Map<String, dynamic>> and Map<String, dynamic>, resolving this error becomes straightforward. Just remember to pass your map directly into the set() method without extra braces. This will help you write your custom user data to Firestore without any complications. Happy coding!