Struct mongodb::sync::Cursor [−][src]
pub struct Cursor<T> where
T: DeserializeOwned + Unpin + Send + Sync, { /* fields omitted */ }
sync
only.Expand description
A Cursor
streams the result of a query. When a query is made, a Cursor
will be returned with
the first batch of results from the server; the documents will be returned as the Cursor
is
iterated. When the batch is exhausted and if there are more results, the Cursor
will fetch the
next batch of documents, and so forth until the results are exhausted. Note that because of this
batching, additional network I/O may occur on any given call to Cursor::next
. Because of this,
a Cursor
iterates over Result<Document>
items rather than simply Document
items.
The batch size of the Cursor
can be configured using the options to the method that returns
it. For example, setting the batch_size
field of
FindOptions
will set the batch size of the
Cursor
returned by Collection::find
.
Note that the batch size determines both the number of documents stored in memory by the
Cursor
at a given time as well as the total number of network round-trips needed to fetch all
results from the server; both of these factors should be taken into account when choosing the
optimal batch size.
A cursor can be used like any other Stream
. The simplest way is just to iterate over the
documents it yields:
for doc in cursor {
println!("{}", doc?)
}
Additionally, all the other methods that an Stream
has are available on Cursor
as well.
This includes all of the functionality provided by StreamExt
, which provides similar functionality to the standard library Iterator
trait.
For instance, if the number of results from a query is known to be small, it might make sense
to collect them into a vector:
let results: Vec<Result<Document>> = cursor.collect();
Trait Implementations
Advances the iterator and returns the next value. Read more
Returns the bounds on the remaining length of the iterator. Read more
Consumes the iterator, counting the number of iterations and returning it. Read more
Consumes the iterator, returning the last element. Read more
🔬 This is a nightly-only experimental API. (iter_advance_by
)
recently added
Advances the iterator by n
elements. Read more
Returns the n
th element of the iterator. Read more
Creates an iterator starting at the same point, but stepping by the given amount at each iteration. Read more
1.0.0[src]fn chain<U>(self, other: U) -> Chain<Self, <U as IntoIterator>::IntoIter> where
U: IntoIterator<Item = Self::Item>,
fn chain<U>(self, other: U) -> Chain<Self, <U as IntoIterator>::IntoIter> where
U: IntoIterator<Item = Self::Item>,
Takes two iterators and creates a new iterator over both in sequence. Read more
1.0.0[src]fn zip<U>(self, other: U) -> Zip<Self, <U as IntoIterator>::IntoIter> where
U: IntoIterator,
fn zip<U>(self, other: U) -> Zip<Self, <U as IntoIterator>::IntoIter> where
U: IntoIterator,
‘Zips up’ two iterators into a single iterator of pairs. Read more
1.56.0[src]fn intersperse(self, separator: Self::Item) -> Intersperse<Self> where
Self::Item: Clone,
fn intersperse(self, separator: Self::Item) -> Intersperse<Self> where
Self::Item: Clone,
Creates a new iterator which places a copy of separator
between adjacent
items of the original iterator. Read more
1.56.0[src]fn intersperse_with<G>(self, separator: G) -> IntersperseWith<Self, G> where
G: FnMut() -> Self::Item,
fn intersperse_with<G>(self, separator: G) -> IntersperseWith<Self, G> where
G: FnMut() -> Self::Item,
Creates a new iterator which places an item generated by separator
between adjacent items of the original iterator. Read more
Takes a closure and creates an iterator which calls that closure on each element. Read more
Calls a closure on each element of an iterator. Read more
Creates an iterator which uses a closure to determine if an element should be yielded. Read more
Creates an iterator that both filters and maps. Read more
Creates an iterator which gives the current iteration count as well as the next value. Read more
Creates an iterator that yields elements based on a predicate. Read more
🔬 This is a nightly-only experimental API. (iter_map_while
)
recently added
Creates an iterator that both yields elements based on a predicate and maps. Read more
Creates an iterator that skips the first n
elements. Read more
Creates an iterator that yields the first n
elements, or fewer
if the underlying iterator ends sooner. Read more
Creates an iterator that works like map, but flattens nested structure. Read more
Creates an iterator that flattens nested structure. Read more
Does something with each element of an iterator, passing the value on. Read more
Transforms an iterator into a collection. Read more
Consumes an iterator, creating two collections from it. Read more
fn partition_in_place<'a, T, P>(self, predicate: P) -> usize where
Self: DoubleEndedIterator<Item = &'a mut T>,
T: 'a,
P: FnMut(&T) -> bool,
fn partition_in_place<'a, T, P>(self, predicate: P) -> usize where
Self: DoubleEndedIterator<Item = &'a mut T>,
T: 'a,
P: FnMut(&T) -> bool,
🔬 This is a nightly-only experimental API. (iter_partition_in_place
)
new API
Reorders the elements of this iterator in-place according to the given predicate,
such that all those that return true
precede all those that return false
.
Returns the number of true
elements found. Read more
🔬 This is a nightly-only experimental API. (iter_is_partitioned
)
new API
Checks if the elements of this iterator are partitioned according to the given predicate,
such that all those that return true
precede all those that return false
. Read more
An iterator method that applies a function as long as it returns successfully, producing a single, final value. Read more
An iterator method that applies a fallible function to each item in the iterator, stopping at the first error and returning that error. Read more
Folds every element into an accumulator by applying an operation, returning the final result. Read more
Reduces the elements to a single one, by repeatedly applying a reducing operation. Read more
Tests if every element of the iterator matches a predicate. Read more
Tests if any element of the iterator matches a predicate. Read more
Searches for an element of an iterator that satisfies a predicate. Read more
Applies function to the elements of iterator and returns the first non-none result. Read more
🔬 This is a nightly-only experimental API. (try_find
)
new API
Applies function to the elements of iterator and returns the first true result or the first error. Read more
Searches for an element in an iterator, returning its index. Read more
1.0.0[src]fn rposition<P>(&mut self, predicate: P) -> Option<usize> where
Self: ExactSizeIterator + DoubleEndedIterator,
P: FnMut(Self::Item) -> bool,
fn rposition<P>(&mut self, predicate: P) -> Option<usize> where
Self: ExactSizeIterator + DoubleEndedIterator,
P: FnMut(Self::Item) -> bool,
Searches for an element in an iterator from the right, returning its index. Read more
Returns the maximum element of an iterator. Read more
Returns the minimum element of an iterator. Read more
Returns the element that gives the maximum value from the specified function. Read more
Returns the element that gives the maximum value with respect to the specified comparison function. Read more
Returns the element that gives the minimum value from the specified function. Read more
Returns the element that gives the minimum value with respect to the specified comparison function. Read more
Reverses an iterator’s direction. Read more
Converts an iterator of pairs into a pair of containers. Read more
Creates an iterator which copies all of its elements. Read more
Sums the elements of an iterator. Read more
Iterates over the entire iterator, multiplying all the elements Read more
Lexicographically compares the elements of this Iterator
with those
of another. Read more
fn cmp_by<I, F>(self, other: I, cmp: F) -> Ordering where
F: FnMut(Self::Item, <I as IntoIterator>::Item) -> Ordering,
I: IntoIterator,
fn cmp_by<I, F>(self, other: I, cmp: F) -> Ordering where
F: FnMut(Self::Item, <I as IntoIterator>::Item) -> Ordering,
I: IntoIterator,
iter_order_by
)Lexicographically compares the elements of this Iterator
with those
of another with respect to the specified comparison function. Read more
1.5.0[src]fn partial_cmp<I>(self, other: I) -> Option<Ordering> where
I: IntoIterator,
Self::Item: PartialOrd<<I as IntoIterator>::Item>,
fn partial_cmp<I>(self, other: I) -> Option<Ordering> where
I: IntoIterator,
Self::Item: PartialOrd<<I as IntoIterator>::Item>,
Lexicographically compares the elements of this Iterator
with those
of another. Read more
fn partial_cmp_by<I, F>(self, other: I, partial_cmp: F) -> Option<Ordering> where
F: FnMut(Self::Item, <I as IntoIterator>::Item) -> Option<Ordering>,
I: IntoIterator,
fn partial_cmp_by<I, F>(self, other: I, partial_cmp: F) -> Option<Ordering> where
F: FnMut(Self::Item, <I as IntoIterator>::Item) -> Option<Ordering>,
I: IntoIterator,
iter_order_by
)Lexicographically compares the elements of this Iterator
with those
of another with respect to the specified comparison function. Read more
1.5.0[src]fn eq<I>(self, other: I) -> bool where
I: IntoIterator,
Self::Item: PartialEq<<I as IntoIterator>::Item>,
fn eq<I>(self, other: I) -> bool where
I: IntoIterator,
Self::Item: PartialEq<<I as IntoIterator>::Item>,
fn eq_by<I, F>(self, other: I, eq: F) -> bool where
F: FnMut(Self::Item, <I as IntoIterator>::Item) -> bool,
I: IntoIterator,
fn eq_by<I, F>(self, other: I, eq: F) -> bool where
F: FnMut(Self::Item, <I as IntoIterator>::Item) -> bool,
I: IntoIterator,
iter_order_by
)1.5.0[src]fn ne<I>(self, other: I) -> bool where
I: IntoIterator,
Self::Item: PartialEq<<I as IntoIterator>::Item>,
fn ne<I>(self, other: I) -> bool where
I: IntoIterator,
Self::Item: PartialEq<<I as IntoIterator>::Item>,
1.5.0[src]fn lt<I>(self, other: I) -> bool where
I: IntoIterator,
Self::Item: PartialOrd<<I as IntoIterator>::Item>,
fn lt<I>(self, other: I) -> bool where
I: IntoIterator,
Self::Item: PartialOrd<<I as IntoIterator>::Item>,
Determines if the elements of this Iterator
are lexicographically
less than those of another. Read more
1.5.0[src]fn le<I>(self, other: I) -> bool where
I: IntoIterator,
Self::Item: PartialOrd<<I as IntoIterator>::Item>,
fn le<I>(self, other: I) -> bool where
I: IntoIterator,
Self::Item: PartialOrd<<I as IntoIterator>::Item>,
Determines if the elements of this Iterator
are lexicographically
less or equal to those of another. Read more
1.5.0[src]fn gt<I>(self, other: I) -> bool where
I: IntoIterator,
Self::Item: PartialOrd<<I as IntoIterator>::Item>,
fn gt<I>(self, other: I) -> bool where
I: IntoIterator,
Self::Item: PartialOrd<<I as IntoIterator>::Item>,
Determines if the elements of this Iterator
are lexicographically
greater than those of another. Read more
1.5.0[src]fn ge<I>(self, other: I) -> bool where
I: IntoIterator,
Self::Item: PartialOrd<<I as IntoIterator>::Item>,
fn ge<I>(self, other: I) -> bool where
I: IntoIterator,
Self::Item: PartialOrd<<I as IntoIterator>::Item>,
Determines if the elements of this Iterator
are lexicographically
greater than or equal to those of another. Read more
🔬 This is a nightly-only experimental API. (is_sorted
)
new API
Checks if the elements of this iterator are sorted. Read more
🔬 This is a nightly-only experimental API. (is_sorted
)
new API
Checks if the elements of this iterator are sorted using the given comparator function. Read more
fn is_sorted_by_key<F, K>(self, f: F) -> bool where
F: FnMut(Self::Item) -> K,
K: PartialOrd<K>,
fn is_sorted_by_key<F, K>(self, f: F) -> bool where
F: FnMut(Self::Item) -> K,
K: PartialOrd<K>,
🔬 This is a nightly-only experimental API. (is_sorted
)
new API
Checks if the elements of this iterator are sorted using the given key extraction function. Read more