Great question! Let’s break down exactly how Gorilla/schema behaves when you skip explicit schema tags on your struct fields, since the docs can feel a bit unclear on this edge case.

1. Does it recognize other tags (like json)? #

By default, no—Gorilla/schema only looks for the schema tag out of the box. If you’re seeing it work with json tags, there are two likely explanations:

• Your json tag name matches the struct field name (e.g., a field UserName with json:"userName" might align with form keys that match either value)
• You’ve explicitly configured the library to use the json tag instead, via code like this:

  decoder := schema.NewDecoder()
  decoder.SetTag("json")
  

That said, you can customize the tag it uses to any string you want with SetTag, but the default is strictly schema.

2. Case-insensitive matching behavior #

Yes! Even without schema tags, Gorilla/schema uses case-insensitive matching between struct field names and form keys. It also handles common separator conversions automatically:

• A struct field like UserName will match form keys like username, user_name, user-name, or even USERNAME
• This matching logic applies whether you’re using schema tags or relying on raw field names

3. Performance impact of skipping schema tags #

The performance difference is negligible for most real-world use cases. Here’s why:

• Gorilla/schema caches struct metadata (field names, tags, types) after the first time it parses a struct type. Subsequent parses reuse this cache, so reflection overhead only hits once.
• The only minor overhead when skipping schema tags is that the library has to convert the raw field name into its "normalized" form (lowercase, handling separators) instead of just using the pre-defined tag value. But this is a trivial string operation that won’t show up in profiling unless you’re parsing thousands of structs per second.

If you’re working in an ultra-high-throughput scenario, you might see a tiny improvement from using schema tags, but for most apps, it’s not worth worrying about.

内容的提问来源于stack exchange，提问作者TopherGopher