Question 1

How do I merge a map into a struct using Mergo?

Accepted Answer

Use the Map function: if err := mergo.Map(&dst, srcMap); err != nil { ... }. It capitalizes map keys to match struct field names, but note it won't merge structs recursively within maps, as per the README.

Question 2

Can Mergo handle merging time.Time fields?

Accepted Answer

Yes, but you need a custom transformer. The README provides an example where a transformer checks if the destination time.Time is zero before overwriting it, allowing proper handling of non-zero values.

Question 3

Mergo vs other Go merging libraries like go-merge?

Accepted Answer

Mergo offers more features like recursive merging and transformers, making it better for configuration management, while go-merge might be simpler but less customizable. Mergo's stability and wide adoption add to its reliability.

Question 4

Why isn't Mergo merging my private struct fields?

Accepted Answer

Mergo only merges exported (public) fields by design, as stated in the README. For private fields, you must handle them manually or restructure your code to use exported fields.

Question 5

How to overwrite all values in the destination with Mergo?

Accepted Answer

Use the WithOverride option: mergo.Merge(&dst, src, mergo.WithOverride). This ensures source values replace destination values even if they are non-zero, useful for configuration overrides.

Question 6

Is Mergo still maintained since it's frozen?

Accepted Answer

Mergo is stable and frozen, meaning no new features are added, but it's production-ready. Bug fixes might be considered for critical issues, but the README notes that development is minimal with a focus on reliability for existing projects.

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