Core Design Decisions

All fields optional by default. Same as graphql
When parsing into structs, private fields are ignored (same as stdlib json.Unmarshal)
The struct parser expects a DataProvider (although if you pass something else to the data field it will try to coerce it into a DataProvider), which is an interface that wraps around an input like a map. This is less efficient than doing it directly but allows us to reuse the same code for all kinds of data sources (i.e json, query params, forms, etc). Generally as a normal user you should ignore that DataProviders exist. So forget you ever read this.
Errors returned by you (for example in a PreTransform or PostTransform function) can be the ZogIssue interface or an error. If you return an error, it will be wrapped in a ZogIssue. ZogIssue is just a struct that wraps around an error and adds a message field which is text that can be shown to the user. For more on this see Errors
You should not depend on test execution order. They might run in parallel in the future

A WORD OF CAUTION. ZOG & PANICS In general Zog will never panic if the input data is wrong but it will panic if you configure it wrong. For example:

In parse mode Zog will never panic due to invalid input data but will always panic if invalid destination is passed to the Parse function. if the destination does not match the schema in terms of types or fields.

In validate mode Zog will panic if the expected types or fields are not present in the structure you are validating.

var schema = z.Struct(z.Schema{
  "name": z.String().Required(),
})
// This struct is a valid destination for the schema
type User struct {
  Name string
  Age int // age will be ignored since it is not a field in the schema
}
// this struct is not a valid structure for the schema. It is missing the name field.
// This will cause Zog to panic in both Parse and Validate mode
type User2 struct {
  Email string
  Age int
}
schema.Parse(map[string]any{"name": "zog"}, &User{}) // this will panic even if input data is valid. Because the destination is not a valid structure for the schema
schema.Validate(&User2{}) // This will panic because the structure does not match the schema

Limitations

Most of these things are issues we would like to address in future versions.

maps are not a supported schema type
structs and slices don't support catch, and structs don't support default values
It is not recommended to use very deeply nested schemas since that requires a lot of reflection and can have a negative impact on performance

Limitations​

Limitations