Struct Rows 

pub struct Rows<E: Entity> { /* private fields */ }

Represent a rows of result.

Implementations

impl<E: Entity> Rows<E>

pub fn get(&self, n: usize) -> E

Retreive the nth row.

Panics

Panics if n is greater than or equal to tuple length.

Examples found in repository

examples/08-composite.rs (line 50)

        pub fn employee_with_department(&self, id: i32) -> elephantry::Result<Entity> {
            use elephantry::{Model, Projectable};

            let employee_projection = Self::create_projection()
                .unset_field("department_id")
                .add_field("departments", "array_agg(depts)")
                .alias("e")
                .to_string();

            let employee = <Self as elephantry::Model>::Structure::relation();

            let sql = format!(
                r#"
with recursive
    depts (department_id, name, parent_id) as (
        select d.department_id, d.name, d.parent_id from department d join {employee} e using(department_id) where e.employee_id = $1
        union all
        select d.department_id, d.name, d.parent_id from depts parent join department d on parent.parent_id = d.department_id
    )
select {employee_projection}
    from {employee} e, depts
    where e.employee_id = $1
    group by e.employee_id
"#
            );

            Ok(self.connection.query::<Entity>(&sql, &[&id])?.get(0))
        }

examples/07-relations.rs (line 50)

        pub fn employee_with_department(&self, id: i32) -> elephantry::Result<Entity> {
            use elephantry::{Model, Projectable};

            let employee_projection = Self::create_projection()
                .unset_field("department_id")
                .add_field("departments", "array_agg(depts)")
                .alias("e")
                .to_string();

            let employee = <Self as elephantry::Model>::Structure::relation();

            let department_projection = super::department::Model::create_projection()
                .alias("d")
                .unset_field("parent")
                .to_string();

            let department = super::department::Structure::relation();

            let sql = format!(
                r#"
with recursive
    depts (department_id, name, parent_id) as (
        select {department_projection} from {department} d join {employee} e using(department_id) where e.employee_id = $1
        union all
        select {department_projection} from depts parent join {department} d on parent.parent_id = d.department_id
    )
select {employee_projection}
    from {employee} e, depts
    where e.employee_id = $1
    group by e.employee_id
"#
            );

            Ok(self.connection.query::<Entity>(&sql, &[&id])?.get(0))
        }

pub fn try_get(&self, n: usize) -> Option<E>

Retreive the nth row, or None if n is greater than or equal to the number of the rows.

pub fn into_vec(self) -> Vec<E>

Converts Rows into a vector.

Methods from Deref<Target = Result>

pub fn get(&self, n: usize) -> Tuple<'_>

Examples found in repository

examples/06-complex.rs (line 19)

        pub fn managers_salary(&self) -> elephantry::Result<f32> {
            let query = "select sum(day_salary) from employee where is_manager";

            let result = self.connection.execute(query)?.get(0).get("sum");

            Ok(result)
        }

examples/01-execute.rs (line 14)

fn main() -> elephantry::Result {
    let database_url =
        std::env::var("DATABASE_URL").unwrap_or_else(|_| "postgres://localhost".to_string());
    let elephantry = elephantry::Pool::new(&database_url)?;
    elephantry.execute(include_str!("structure.sql"))?;

    let results = elephantry.execute("select * from department")?;

    for result in &results {
        let name: String = result.get("name");
        println!("- {name}");
    }

    let parent_id: Option<i32> = results.get(0).get("parent_id");
    dbg!(parent_id);

    match results.get(0).try_get::<i32>("parent_id") {
        Ok(_) => (),
        Err(err) => eprintln!("Error: {err:?}"),
    }

    match results.get(0).try_get::<i32>("missing_field") {
        Ok(_) => (),
        Err(err) => eprintln!("Error: {err:?}"),
    }

    Ok(())
}

pub fn try_get(&self, n: usize) -> Option<Tuple<'_>>

pub fn len(&self) -> usize

pub fn is_empty(&self) -> bool

pub fn state(&self) -> Result<Option<State>>

Methods from Deref<Target = Result>

pub fn status(&self) -> Status

Returns the result status of the command.

See PQresultStatus.

pub fn error_message(&self) -> Result<Option<String>, Error>

Returns the error message associated with the command, or an empty string if there was no error.

See PQresultErrorMessage.

pub fn verbose_error_message( &self, verbosity: Verbosity, show_context: ContextVisibility, ) -> Result<Option<String>, Error>

Returns a reformatted version of the error message associated with a Result object.

See PQresultVerboseErrorMessage.

pub fn error_field( &self, field: ErrorField, ) -> Result<Option<&'static str>, Error>

Returns a reformatted version of the error message associated with a libpq::Result object.

See PQresultErrorField.

pub fn ntuples(&self) -> usize

Returns the number of rows (tuples) in the query result.

See PQntuples.

pub fn nfields(&self) -> usize

Returns the number of columns (fields) in each row of the query result.

See PQnfields.

pub fn field_name(&self, number: usize) -> Result<Option<String>, Error>

Returns the column name associated with the given column number.

See PQfname.

pub fn field_number(&self, name: &str) -> Option<usize>

Returns the column number associated with the given column name.

See PQfnumber.

pub fn field_table(&self, column: usize) -> Option<u32>

Returns the OID of the table from which the given column was fetched.

See PQftable.

pub fn field_tablecol(&self, column: usize) -> usize

Returns the column number (within its table) of the column making up the specified query result column.

See PQftablecol.

pub fn field_format(&self, column: usize) -> Format

Returns the format code indicating the format of the given column.

See PQfformat.

pub fn field_type(&self, column: usize) -> u32

Returns the data type associated with the given column number.

See PQftype.

pub fn field_mod(&self, column: usize) -> Option<i32>

Returns the type modifier of the column associated with the given column number.

See PQfmod.

pub fn field_size(&self, column: usize) -> Option<usize>

Returns the size in bytes of the column associated with the given column number.

None indicates the data type is variable-length.

See PQfsize.

pub fn binary_tuples(&self) -> bool

Returns true if the Result contains binary data and false if it contains text data.

See PQbinaryTuples.

pub fn value(&self, row: usize, column: usize) -> Option<&[u8]>

Returns a single field value of one row of a Result.

See PQgetvalue.

pub fn is_null(&self, row: usize, column: usize) -> bool

Tests a field for a null value.

See PQgetisnull.

pub fn length(&self, row: usize, column: usize) -> usize

Returns the actual length of a field value in bytes.

See PQgetlength.

pub fn nparams(&self) -> usize

Returns the number of parameters of a prepared statement.

See PQnparams.

pub fn param_type(&self, param: usize) -> Option<u32>

Returns the data type of the indicated statement parameter.

See PQparamtype.

pub fn print(&self, output: &dyn AsRawFd, option: &Options)

Available on Unix only.

Prints out all the rows and, optionally, the column names to the specified output stream.

See PQprint.

pub fn cmd_status(&self) -> Result<Option<String>, Error>

Returns the command status tag from the SQL command that generated the Result.

See PQcmdStatus.

pub fn cmd_tuples(&self) -> Result<usize, Error>

Returns the number of rows affected by the SQL command.

See PQcmdTuples.

pub fn oid_value(&self) -> Option<u32>

Returns the OID of the inserted row.

See PQoidValue.

pub fn oid_status(&self) -> Result<Option<String>, Error>

👎Deprecated:

This function is deprecated in favor of libpq::Result::oid_value and is not thread-safe.

See PQoidStatus.

pub fn copy(&self, flags: i32) -> Result<PQResult, Error>

Makes a copy of a Result object.

See PQcopyResult.

pub fn memory_size(&self) -> u64

Available on crate feature v12 only.

Retrieves the number of bytes allocated for a Result object.

See PQresultMemorySize

pub fn display_tuples( &self, file: File, fill_align: bool, field_sep: Option<&str>, print_header: bool, quiet: bool, )

Available on Unix only.

Really old printing routines.

Trait Implementations

impl<E: Debug + Entity> Debug for Rows<E>

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

Formats the value using the given formatter.

impl<E: Entity> Deref for Rows<E>

type Target = Result

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl<E: Entity> From<Result> for Rows<E>

fn from(result: Result) -> Self

Converts to this type from the input type.

impl<E: Entity> Iterator for Rows<E>

type Item = E

The type of the elements being iterated over.

fn next(&mut self) -> Option<Self::Item>

Advances the iterator and returns the next value.

fn next_chunk<const N: usize>( &mut self, ) -> Result<[Self::Item; N], IntoIter<Self::Item, N>>

where Self: Sized,

🔬This is a nightly-only experimental API. (iter_next_chunk)

Advances the iterator and returns an array containing the next N values.

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

Returns the bounds on the remaining length of the iterator.

fn count(self) -> usize

where Self: Sized,

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

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

where Self: Sized,

Consumes the iterator, returning the last element.

fn advance_by(&mut self, n: usize) -> Result<(), NonZero<usize>>

🔬This is a nightly-only experimental API. (iter_advance_by)

Advances the iterator by n elements.

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

Returns the nth element of the iterator.

fn step_by(self, step: usize) -> StepBy<Self>

where Self: Sized,

Creates an iterator starting at the same point, but stepping by the given amount at each iteration.

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

where Self: Sized, 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 as IntoIterator>::IntoIter>

where Self: Sized, U: IntoIterator,

‘Zips up’ two iterators into a single iterator of pairs.

fn intersperse(self, separator: Self::Item) -> Intersperse<Self>

where Self: Sized, Self::Item: Clone,

🔬This is a nightly-only experimental API. (iter_intersperse)

Creates a new iterator which places a copy of separator between items of the original iterator.

fn intersperse_with<G>(self, separator: G) -> IntersperseWith<Self, G>

where Self: Sized, G: FnMut() -> Self::Item,

🔬This is a nightly-only experimental API. (iter_intersperse)

Creates a new iterator which places an item generated by separator between items of the original iterator.

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

where Self: Sized, F: FnMut(Self::Item) -> B,

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

fn for_each<F>(self, f: F)

where Self: Sized, F: FnMut(Self::Item),

Calls a closure on each element of an iterator.

fn filter<P>(self, predicate: P) -> Filter<Self, P>

where Self: Sized, 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 Self: Sized, F: FnMut(Self::Item) -> Option<B>,

Creates an iterator that both filters and maps.

fn enumerate(self) -> Enumerate<Self>

where Self: Sized,

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

fn peekable(self) -> Peekable<Self>

where Self: Sized,

Creates an iterator which can use the peek and peek_mut methods to look at the next element of the iterator without consuming it. See their documentation for more information.

fn skip_while<P>(self, predicate: P) -> SkipWhile<Self, P>

where Self: Sized, P: FnMut(&Self::Item) -> bool,

Creates an iterator that skips elements based on a predicate.

fn take_while<P>(self, predicate: P) -> TakeWhile<Self, P>

where Self: Sized, P: FnMut(&Self::Item) -> bool,

Creates an iterator that yields elements based on a predicate.

fn map_while<B, P>(self, predicate: P) -> MapWhile<Self, P>

where Self: Sized, P: FnMut(Self::Item) -> Option<B>,

Creates an iterator that both yields elements based on a predicate and maps.

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

where Self: Sized,

Creates an iterator that skips the first n elements.

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

where Self: Sized,

Creates an iterator that yields the first n elements, or fewer if the underlying iterator ends sooner.

fn scan<St, B, F>(self, initial_state: St, f: F) -> Scan<Self, St, F>

where Self: Sized, F: FnMut(&mut St, Self::Item) -> Option<B>,

An iterator adapter which, like fold, holds internal state, but unlike fold, produces a new iterator.

fn flat_map<U, F>(self, f: F) -> FlatMap<Self, U, F>

where Self: Sized, U: IntoIterator, F: FnMut(Self::Item) -> U,

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

fn flatten(self) -> Flatten<Self>

where Self: Sized, Self::Item: IntoIterator,

Creates an iterator that flattens nested structure.

fn map_windows<F, R, const N: usize>(self, f: F) -> MapWindows<Self, F, N>

where Self: Sized, F: FnMut(&[Self::Item; N]) -> R,

🔬This is a nightly-only experimental API. (iter_map_windows)

Calls the given function f for each contiguous window of size N over self and returns an iterator over the outputs of f. Like slice::windows(), the windows during mapping overlap as well.

fn fuse(self) -> Fuse<Self>

where Self: Sized,

Creates an iterator which ends after the first None.

fn inspect<F>(self, f: F) -> Inspect<Self, F>

where Self: Sized, F: FnMut(&Self::Item),

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

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

where Self: Sized,

Creates a “by reference” adapter for this instance of Iterator.

fn collect<B>(self) -> B

where B: FromIterator<Self::Item>, Self: Sized,

Transforms an iterator into a collection.

fn try_collect<B>( &mut self, ) -> <<Self::Item as Try>::Residual as Residual<B>>::TryType

where Self: Sized, Self::Item: Try, <Self::Item as Try>::Residual: Residual<B>, B: FromIterator<<Self::Item as Try>::Output>,

🔬This is a nightly-only experimental API. (iterator_try_collect)

Fallibly transforms an iterator into a collection, short circuiting if a failure is encountered.

fn collect_into<E>(self, collection: &mut E) -> &mut E

where E: Extend<Self::Item>, Self: Sized,

🔬This is a nightly-only experimental API. (iter_collect_into)

Collects all the items from an iterator into a collection.

fn partition<B, F>(self, f: F) -> (B, B)

where Self: Sized, B: Default + Extend<Self::Item>, F: FnMut(&Self::Item) -> bool,

Consumes an iterator, creating two collections from it.

fn is_partitioned<P>(self, predicate: P) -> bool

where Self: Sized, P: FnMut(Self::Item) -> bool,

🔬This is a nightly-only experimental API. (iter_is_partitioned)

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.

fn try_fold<B, F, R>(&mut self, init: B, f: F) -> R

where Self: Sized, F: FnMut(B, Self::Item) -> R, R: Try<Output = B>,

An iterator method that applies a function as long as it returns successfully, producing a single, final value.

fn try_for_each<F, R>(&mut self, f: F) -> R

where Self: Sized, F: FnMut(Self::Item) -> R, R: Try<Output = ()>,

An iterator method that applies a fallible function to each item in the iterator, stopping at the first error and returning that error.

fn fold<B, F>(self, init: B, f: F) -> B

where Self: Sized, F: FnMut(B, Self::Item) -> B,

Folds every element into an accumulator by applying an operation, returning the final result.

fn reduce<F>(self, f: F) -> Option<Self::Item>

where Self: Sized, F: FnMut(Self::Item, Self::Item) -> Self::Item,

Reduces the elements to a single one, by repeatedly applying a reducing operation.

fn try_reduce<R>( &mut self, f: impl FnMut(Self::Item, Self::Item) -> R, ) -> <<R as Try>::Residual as Residual<Option<<R as Try>::Output>>>::TryType

where Self: Sized, R: Try<Output = Self::Item>, <R as Try>::Residual: Residual<Option<Self::Item>>,

🔬This is a nightly-only experimental API. (iterator_try_reduce)

Reduces the elements to a single one by repeatedly applying a reducing operation. If the closure returns a failure, the failure is propagated back to the caller immediately.

fn all<F>(&mut self, f: F) -> bool

where Self: Sized, F: FnMut(Self::Item) -> bool,

Tests if every element of the iterator matches a predicate.

fn any<F>(&mut self, f: F) -> bool

where Self: Sized, 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 Self: Sized, P: FnMut(&Self::Item) -> bool,

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

fn find_map<B, F>(&mut self, f: F) -> Option<B>

where Self: Sized, F: FnMut(Self::Item) -> Option<B>,

Applies function to the elements of iterator and returns the first non-none result.

fn try_find<R>( &mut self, f: impl FnMut(&Self::Item) -> R, ) -> <<R as Try>::Residual as Residual<Option<Self::Item>>>::TryType

where Self: Sized, R: Try<Output = bool>, <R as Try>::Residual: Residual<Option<Self::Item>>,

🔬This is a nightly-only experimental API. (try_find)

Applies function to the elements of iterator and returns the first true result or the first error.

fn position<P>(&mut self, predicate: P) -> Option<usize>

where Self: Sized, P: FnMut(Self::Item) -> bool,

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

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

where Self: Sized, Self::Item: Ord,

Returns the maximum element of an iterator.

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

where Self: Sized, 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, Self: Sized, F: FnMut(&Self::Item) -> B,

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

fn max_by<F>(self, compare: F) -> Option<Self::Item>

where Self: Sized, F: FnMut(&Self::Item, &Self::Item) -> Ordering,

Returns the element that gives the maximum value with respect to the specified comparison function.

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

where B: Ord, Self: Sized, F: FnMut(&Self::Item) -> B,

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

fn min_by<F>(self, compare: F) -> Option<Self::Item>

where Self: Sized, F: FnMut(&Self::Item, &Self::Item) -> Ordering,

Returns the element that gives the minimum value with respect to the specified comparison function.

fn unzip<A, B, FromA, FromB>(self) -> (FromA, FromB)

where FromA: Default + Extend<A>, FromB: Default + Extend<B>, Self: Sized + Iterator<Item = (A, B)>,

Converts an iterator of pairs into a pair of containers.

fn copied<'a, T>(self) -> Copied<Self>

where T: Copy + 'a, Self: Sized + Iterator<Item = &'a T>,

Creates an iterator which copies all of its elements.

fn cloned<'a, T>(self) -> Cloned<Self>

where T: Clone + 'a, Self: Sized + Iterator<Item = &'a T>,

Creates an iterator which clones all of its elements.

fn array_chunks<const N: usize>(self) -> ArrayChunks<Self, N>

where Self: Sized,

🔬This is a nightly-only experimental API. (iter_array_chunks)

Returns an iterator over N elements of the iterator at a time.

fn sum<S>(self) -> S

where Self: Sized, S: Sum<Self::Item>,

Sums the elements of an iterator.

fn product<P>(self) -> P

where Self: Sized, P: Product<Self::Item>,

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, Self: Sized,

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

fn cmp_by<I, F>(self, other: I, cmp: F) -> Ordering

where Self: Sized, I: IntoIterator, F: FnMut(Self::Item, <I as IntoIterator>::Item) -> Ordering,

🔬This is a nightly-only experimental API. (iter_order_by)

Lexicographically compares the elements of this Iterator with those of another with respect to the specified comparison function.

fn partial_cmp<I>(self, other: I) -> Option<Ordering>

where I: IntoIterator, Self::Item: PartialOrd<<I as IntoIterator>::Item>, Self: Sized,

Lexicographically compares the PartialOrd elements of this Iterator with those of another. The comparison works like short-circuit evaluation, returning a result without comparing the remaining elements. As soon as an order can be determined, the evaluation stops and a result is returned.

fn partial_cmp_by<I, F>(self, other: I, partial_cmp: F) -> Option<Ordering>

where Self: Sized, I: IntoIterator, F: FnMut(Self::Item, <I as IntoIterator>::Item) -> Option<Ordering>,

🔬This is a nightly-only experimental API. (iter_order_by)

Lexicographically compares the elements of this Iterator with those of another with respect to the specified comparison function.

fn eq<I>(self, other: I) -> bool

where I: IntoIterator, Self::Item: PartialEq<<I as IntoIterator>::Item>, Self: Sized,

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

fn eq_by<I, F>(self, other: I, eq: F) -> bool

where Self: Sized, I: IntoIterator, F: FnMut(Self::Item, <I as IntoIterator>::Item) -> bool,

🔬This is a nightly-only experimental API. (iter_order_by)

Determines if the elements of this Iterator are equal to those of another with respect to the specified equality function.

fn ne<I>(self, other: I) -> bool

where I: IntoIterator, Self::Item: PartialEq<<I as IntoIterator>::Item>, Self: Sized,

Determines if the elements of this Iterator are not equal to those of another.

fn lt<I>(self, other: I) -> bool

where I: IntoIterator, Self::Item: PartialOrd<<I as IntoIterator>::Item>, Self: Sized,

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 as IntoIterator>::Item>, Self: Sized,

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 as IntoIterator>::Item>, Self: Sized,

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 as IntoIterator>::Item>, Self: Sized,

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

fn is_sorted(self) -> bool

where Self: Sized, Self::Item: PartialOrd,

Checks if the elements of this iterator are sorted.

fn is_sorted_by<F>(self, compare: F) -> bool

where Self: Sized, F: FnMut(&Self::Item, &Self::Item) -> bool,

Checks if the elements of this iterator are sorted using the given comparator function.

fn is_sorted_by_key<F, K>(self, f: F) -> bool

where Self: Sized, F: FnMut(Self::Item) -> K, K: PartialOrd,

Checks if the elements of this iterator are sorted using the given key extraction function.

impl<E: Entity + Serialize> Serialize for Rows<E>

Available on crate feature serde only.

fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>

where S: Serializer,

Serialize this value into the given Serde serializer.