Struct Projection 

pub struct Projection<T> {
    pub value: T,
    pub selected: Vec<&'static str>,
}

Result of a .select(...)-projected read. Holds the model with only the selected columns populated — non-selected fields carry their type’s Default::default() value ("" for String, 0 for integers, None for Option<T>, etc.).

Caller responsibility: check Self::is_selected before reading a field if you need to distinguish “real zero-valued DB row” from “the runtime didn’t fetch this column”. For typical use — fetch one or two specific columns for a route that needs only those — just read the fields you asked for and don’t read the others.

Compile-time constraint: every model field type must impl Default. The codegen emits a #[derive(Default)] on the model struct; any field type that doesn’t satisfy Default (typically a Json<MyCustomType> where MyCustomType doesn’t derive Default) becomes a compile error at the include_server_schema! / include_embedded_schema! boundary. Wrap the offending field in Option or derive Default on the custom struct.

Fields

value: T

selected: Vec<&'static str>

Implementations

impl<T> Projection<T>

pub fn into_inner(self) -> T

Consume the projection and return the underlying model. The selection metadata is dropped — only do this when you already know which fields you asked for.

pub fn is_selected(&self, column: &str) -> bool

Was this SQL column populated by the runtime? Pass the column’s SQL name (the sql_name from ModelColumn, typically the snake_case form). Reading the corresponding Rust field is only meaningful when this returns true.

Trait Implementations

impl<T> Clone for Projection<T>

where T: Clone,

fn clone(&self) -> Projection<T>

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<T> Debug for Projection<T>

where T: Debug,

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl<T> PartialEq for Projection<T>

where T: PartialEq,

fn eq(&self, other: &Projection<T>) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<T> StructuralPartialEq for Projection<T>