Skip to main content

Row

Struct Row 

Source
pub struct Row { /* private fields */ }
Expand description

A container for a single row within a query result set.

RowIterator::next() yields a Row.

Each Row contains parsed cell values and a reference to the table schema.

§Zero-Copy Struct Mapping via Derive Macros

Define typed structs with #[derive(FromRow)] to convert rows directly into your domain types using TryFrom<Row> without unnecessary allocations:

#[derive(FromRow, Debug)]
struct UserStats {
    name: String,
    count: i64,
}

let user: UserStats = row.try_into()?;
println!("{}: {}", user.name, user.count);

§Field Extraction by Name or Index

Retrieve individual cell values by column name (&str) or index (usize) using get() or take():

let name: String = row.get("name")?;
let age: i64 = row.get(1)?;
println!("{name} is {age} years old");

Implementations§

Source§

impl Row

Source

pub fn get<T: FromSql, I: ColumnIndex>(&self, index: I) -> Result<T, RowError>

Retrieves a value from the row by column name or zero-based index.

The return type must implement FromSql.

The cell value is cloned from the row data without modifying self. If you want to take ownership and avoid cloning large values, see take().

§Example
let msg: String = row.get("msg")?;
println!("Value: {msg}");
Source

pub fn take<T: FromSql, I: ColumnIndex>( &mut self, index: I, ) -> Result<T, RowError>

Takes ownership of a value from the row by column name or zero-based index.

This method mutates self by extracting the cell value in-place to avoid cloning. The extracted cell in the row is replaced with NULL. Subsequent attempts to read or take the column will treat it as NULL (returning Ok(None) when reading into Option<T>, or returning a type conversion error for non-nullable types).

take() removes the value from self before converting it to T. If type conversion fails and returns an error, the original value has already been consumed and cannot be recovered from the row.

If you are not sure of the column’s type or need to read the value multiple times, use get() instead of take(). Use take() when you are confident of the type and want to avoid cloning large values (such as strings, byte buffers, or nested records).

§Example
let text: String = row.take("big_text")?;
println!("Length: {}", text.len());

// Subsequent reads treat the column as NULL:
assert_eq!(row.get::<Option<String>, _>("big_text")?, None);

// Attempting to read or take again as a non-nullable type fails:
assert!(row.take::<String, _>("big_text").is_err());

Trait Implementations§

Source§

impl Clone for Row

Source§

fn clone(&self) -> Self

Returns a duplicate of the value. Read more
1.0.0 (const: unstable) · Source§

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

Performs copy-assignment from source. Read more
Source§

impl Debug for Row

Source§

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

Formats the value using the given formatter. Read more

Auto Trait Implementations§

§

impl Freeze for Row

§

impl RefUnwindSafe for Row

§

impl Send for Row

§

impl Sync for Row

§

impl Unpin for Row

§

impl UnsafeUnpin for Row

§

impl UnwindSafe for Row

Blanket Implementations§

Source§

impl<T> Any for T
where T: 'static + ?Sized,

Source§

fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
Source§

impl<T> Borrow<T> for T
where T: ?Sized,

Source§

fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
Source§

impl<T> BorrowMut<T> for T
where T: ?Sized,

Source§

fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
Source§

impl<ST, DT> CastableFrom<ST, Initialized, Initialized> for DT
where ST: ?Sized, DT: ?Sized,

Source§

impl<ST, DT> CastableFrom<ST, Uninit, Uninit> for DT
where ST: ?Sized, DT: ?Sized,

Source§

impl<T> CloneToUninit for T
where T: Clone,

Source§

unsafe fn clone_to_uninit(&self, dest: *mut u8)

🔬This is a nightly-only experimental API. (clone_to_uninit)
Performs copy-assignment from self to dest. Read more
Source§

impl<T> From<T> for T

Source§

fn from(t: T) -> T

Returns the argument unchanged.

Source§

impl<T> FutureExt for T

Source§

fn with_context(self, otel_cx: Context) -> WithContext<Self> ⓘ

Attaches the provided Context to this type, returning a WithContext wrapper. Read more
Source§

fn with_current_context(self) -> WithContext<Self> ⓘ

Attaches the current Context to this type, returning a WithContext wrapper. Read more
Source§

impl<T> Instrument for T

Source§

fn instrument(self, span: Span) -> Instrumented<Self> ⓘ

Instruments this type with the provided Span, returning an Instrumented wrapper. Read more
Source§

fn in_current_span(self) -> Instrumented<Self> ⓘ

Instruments this type with the current Span, returning an Instrumented wrapper. Read more
Source§

impl<T, U> Into<U> for T
where U: From<T>,

Source§

fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

Source§

impl<T> IntoRequest<T> for T

Source§

fn into_request(self) -> Request<T>

Wrap the input message T in a tonic::Request
Source§

impl<L> LayerExt<L> for L

Source§

fn named_layer<S>(&self, service: S) -> Layered<<L as Layer<S>>::Service, S>
where L: Layer<S>,

Applies the layer to a service and wraps it in Layered.
Source§

impl<T> PolicyExt for T
where T: ?Sized,

Source§

fn and<P, B, E>(self, other: P) -> And<T, P>
where T: Sized + Policy<B, E>, P: Policy<B, E>,

Create a new Policy that returns Action::Follow only if self and other return Action::Follow. Read more
Source§

fn or<P, B, E>(self, other: P) -> Or<T, P>
where T: Sized + Policy<B, E>, P: Policy<B, E>,

Create a new Policy that returns Action::Follow if either self or other returns Action::Follow. Read more
Source§

impl<T> Read<Exclusive, BecauseExclusive> for T
where T: ?Sized,

Source§

impl<T> Same for T

Source§

type Output = T

Should always be Self
Source§

impl<T> ToOwned for T
where T: Clone,

Source§

type Owned = T

The resulting type after obtaining ownership.
Source§

fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
Source§

fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
Source§

impl<T, U> TryFrom<U> for T
where U: Into<T>,

Source§

type Error = !

The type returned in the event of a conversion error.
Source§

fn try_from(value: U) -> Result<T, !>

Performs the conversion.
Source§

impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

Source§

type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
Source§

fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.
Source§

impl<V, T> VZip<V> for T
where V: MultiLane<T>,

Source§

fn vzip(self) -> V

Source§

impl<T> WithSubscriber for T

Source§

fn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self> ⓘ
where S: Into<Dispatch>,

Attaches the provided Subscriber to this type, returning a WithDispatch wrapper. Read more
Source§

fn with_current_subscriber(self) -> WithDispatch<Self> ⓘ

Attaches the current default Subscriber to this type, returning a WithDispatch wrapper. Read more