Module builder 

Type-level markers for the generated typestate builders.

Every struct-shaped type include_*_schema! emits — model structs, Create{Model}Input/Update{Model}Input, {Model}Where, {Model}OrderByClause, {Model}FindManyInput, view structs, type structs, and per-procedure Args — gets a companion {Type}Builder whose build() method only exists once every required field has been set. The “has this slot been filled” bit is carried in the type system by these two markers, one type parameter per required field:

pub struct CreateBoardInputBuilder<S0 = Unset, S1 = Unset> { .. }

impl<S0, S1> CreateBoardInputBuilder<S0, S1> {
    pub fn id(self, value: i64) -> CreateBoardInputBuilder<Set, S1> { .. }
    pub fn name(self, value: impl Into<String>) -> CreateBoardInputBuilder<S0, Set> { .. }
}

impl CreateBoardInputBuilder<Set, Set> {
    pub fn build(self) -> CreateBoardInput { .. }   // infallible
}

Forgetting .name(..) is therefore a compile error (“no method named build found for struct CreateBoardInputBuilder<Set, Unset>”), not a runtime Result the caller has to handle. Optional fields (Option<T> and Vec<T> — the two shapes whose Default is exactly the right “caller said nothing” value) get no state parameter at all: their setters return Self, so an all-optional struct like {Model}Where has a plain non-generic builder.

Both markers are uninhabited on purpose: they exist only as type-level bits inside a PhantomData, and nothing should ever hold a value of either one.

Enums

Set

Type-level “this required field has been set”.

Unset

Type-level “this required field has not been set yet” — the default every state parameter starts at.