Struct rusqlite::Rows

pub struct Rows<'stmt> {
    // some fields omitted
}

An iterator over the resulting rows of a query.

Warning

Due to the way SQLite returns result rows of a query, it is not safe to attempt to get values from a row after it has become stale (i.e., next() has been called again on the Rows iterator). For example:

fn bad_function_will_panic(conn: &Connection) -> Result<i64> {
    let mut stmt = try!(conn.prepare("SELECT id FROM my_table"));
    let mut rows = try!(stmt.query(&[]));

    let row0 = try!(rows.next().unwrap());
    // row 0 is value now...

    let row1 = try!(rows.next().unwrap());
    // row 0 is now STALE, and row 1 is valid

    let my_id = row0.get(0); // WILL PANIC because row 0 is stale
    Ok(my_id)
}

Please note that this means some of the methods on Iterator are not useful, such as collect (which would result in a collection of rows, only the last of which can safely be used) and min/max (which could return a stale row unless the last row happened to be the min or max, respectively).

This problem could be solved by changing the signature of next to tie the lifetime of the returned row to the lifetime of (a mutable reference to) the result rows handle, but this would no longer implement Iterator, and therefore you would lose access to the majority of functions which are useful (such as support for for ... in ... looping, map, filter, etc.).

Trait Implementations

impl<'stmt> Iterator for Rows<'stmt>

type Item = Result<Row<'stmt>>

The type of the elements being iterated over.

fn next(&mut self) -> Option<Result<Row<'stmt>>>

Advances the iterator and returns the next value.

fn size_hint(&self) -> (usize, Option<usize>)

Returns the bounds on the remaining length of the iterator.

fn count(self) -> usize

Consumes the iterator, counting the number of iterations and returning it.

fn last(self) -> Option<Self::Item>

Consumes the iterator, returning the last element.

fn nth(&mut self, n: usize) -> Option<Self::Item>

Consumes the n first elements of the iterator, then returns the next() one.

fn chain<U>(self, other: U) -> Chain<Self, U::IntoIter> where U: IntoIterator<Item=Self::Item>

Takes two iterators and creates a new iterator over both in sequence.

fn zip<U>(self, other: U) -> Zip<Self, U::IntoIter> where U: IntoIterator

'Zips up' two iterators into a single iterator of pairs.

fn map<B, F>(self, f: F) -> Map<Self, F> where F: FnMut(Self::Item) -> B

Takes a closure and creates an iterator which calls that closure on each element.

fn filter<P>(self, predicate: P) -> Filter<Self, P> where P: FnMut(&Self::Item) -> bool

Creates an iterator which uses a closure to determine if an element should be yielded.

fn filter_map<B, F>(self, f: F) -> FilterMap<Self, F> where F: FnMut(Self::Item) -> Option<B>

Creates an iterator that both filters and maps.

fn enumerate(self) -> Enumerate<Self>

Creates an iterator which gives the current iteration count as well as the next value.

fn peekable(self) -> Peekable<Self>

Creates an iterator which can use peek to look at the next element of the iterator without consuming it.

fn skip_while<P>(self, predicate: P) -> SkipWhile<Self, P> where P: FnMut(&Self::Item) -> bool

Creates an iterator that [skip()]s elements based on a predicate.

fn take_while<P>(self, predicate: P) -> TakeWhile<Self, P> where P: FnMut(&Self::Item) -> bool

Creates an iterator that yields elements based on a predicate.

fn skip(self, n: usize) -> Skip<Self>

Creates an iterator that skips the first n elements.

fn take(self, n: usize) -> Take<Self>

Creates an iterator that yields its first n elements.

fn scan<St, B, F>(self, initial_state: St, f: F) -> Scan<Self, St, F> where F: FnMut(&mut St, Self::Item) -> Option<B>

An iterator adaptor similar to [fold()] that holds internal state and produces a new iterator.

fn flat_map<U, F>(self, f: F) -> FlatMap<Self, U, F> where F: FnMut(Self::Item) -> U, U: IntoIterator

Creates an iterator that works like map, but flattens nested structure.

fn fuse(self) -> Fuse<Self>

Creates an iterator which ends after the first None.

fn inspect<F>(self, f: F) -> Inspect<Self, F> where F: FnMut(&Self::Item) -> ()

Do something with each element of an iterator, passing the value on.

fn by_ref(&mut self) -> &mut Self

Borrows an iterator, rather than consuming it.

fn collect<B>(self) -> B where B: FromIterator<Self::Item>

Transforms an iterator into a collection.

fn partition<B, F>(self, f: F) -> (B, B) where B: Default + Extend<Self::Item>, F: FnMut(&Self::Item) -> bool

Consumes an iterator, creating two collections from it.

fn fold<B, F>(self, init: B, f: F) -> B where F: FnMut(B, Self::Item) -> B

An iterator adaptor that applies a function, producing a single, final value.

fn all<F>(&mut self, f: F) -> bool where F: FnMut(Self::Item) -> bool

Tests if every element of the iterator matches a predicate.

fn any<F>(&mut self, f: F) -> bool where F: FnMut(Self::Item) -> bool

Tests if any element of the iterator matches a predicate.

fn find<P>(&mut self, predicate: P) -> Option<Self::Item> where P: FnMut(&Self::Item) -> bool

Searches for an element of an iterator that satisfies a predicate.

fn position<P>(&mut self, predicate: P) -> Option<usize> where P: FnMut(Self::Item) -> bool

Searches for an element in an iterator, returning its index.

fn rposition<P>(&mut self, predicate: P) -> Option<usize> where P: FnMut(Self::Item) -> bool, Self: ExactSizeIterator + DoubleEndedIterator

Searches for an element in an iterator from the right, returning its index.

fn max(self) -> Option<Self::Item> where Self::Item: Ord

Returns the maximum element of an iterator.

fn min(self) -> Option<Self::Item> where Self::Item: Ord

Returns the minimum element of an iterator.

fn max_by_key<B, F>(self, f: F) -> Option<Self::Item> where B: Ord, F: FnMut(&Self::Item) -> B

Returns the element that gives the maximum value from the specified function.

fn min_by_key<B, F>(self, f: F) -> Option<Self::Item> where B: Ord, F: FnMut(&Self::Item) -> B

Returns the element that gives the minimum value from the specified function.

fn rev(self) -> Rev<Self> where Self: DoubleEndedIterator

Reverses an iterator's direction.

fn unzip<A, B, FromA, FromB>(self) -> (FromA, FromB) where FromA: Default + Extend<A>, FromB: Default + Extend<B>, Self: Iterator<Item=(A, B)>

Converts an iterator of pairs into a pair of containers.

fn cloned<'a, T>(self) -> Cloned<Self> where Self: Iterator<Item=&'a T>, T: 'a + Clone

Creates an iterator which clone()s all of its elements.

fn cycle(self) -> Cycle<Self> where Self: Clone

Repeats an iterator endlessly.

fn sum<S>(self) -> S where S: Add<Self::Item, Output=S> + Zero

Sums the elements of an iterator.

fn product<P>(self) -> P where P: Mul<Self::Item, Output=P> + One

Iterates over the entire iterator, multiplying all the elements

fn cmp<I>(self, other: I) -> Ordering where I: IntoIterator<Item=Self::Item>, Self::Item: Ord

Lexicographically compares the elements of this Iterator with those of another.

fn partial_cmp<I>(self, other: I) -> Option<Ordering> where I: IntoIterator, Self::Item: PartialOrd<I::Item>

Lexicographically compares the elements of this Iterator with those of another.

fn eq<I>(self, other: I) -> bool where I: IntoIterator, Self::Item: PartialEq<I::Item>

Determines if the elements of this Iterator are equal to those of another.

fn ne<I>(self, other: I) -> bool where I: IntoIterator, Self::Item: PartialEq<I::Item>

Determines if the elements of this Iterator are unequal to those of another.

fn lt<I>(self, other: I) -> bool where I: IntoIterator, Self::Item: PartialOrd<I::Item>

Determines if the elements of this Iterator are lexicographically less than those of another.

fn le<I>(self, other: I) -> bool where I: IntoIterator, Self::Item: PartialOrd<I::Item>

Determines if the elements of this Iterator are lexicographically less or equal to those of another.

fn gt<I>(self, other: I) -> bool where I: IntoIterator, Self::Item: PartialOrd<I::Item>

Determines if the elements of this Iterator are lexicographically greater than those of another.

fn ge<I>(self, other: I) -> bool where I: IntoIterator, Self::Item: PartialOrd<I::Item>

Determines if the elements of this Iterator are lexicographically greater than or equal to those of another.