257 lines
6.5 KiB
Rust
257 lines
6.5 KiB
Rust
//! Rows.
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use crate::row::sealed::{AsName, Sealed};
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use crate::statement::Column;
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use crate::types::{FromSql, Type, WrongType};
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use crate::{Error, Statement};
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use fallible_iterator::FallibleIterator;
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use postgres_protocol::message::backend::DataRowBody;
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use std::fmt;
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use std::ops::Range;
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use std::str;
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use std::sync::Arc;
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mod sealed {
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pub trait Sealed {}
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pub trait AsName {
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fn as_name(&self) -> &str;
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}
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}
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impl AsName for Column {
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fn as_name(&self) -> &str {
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self.name()
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}
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}
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impl AsName for String {
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fn as_name(&self) -> &str {
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self
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}
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}
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/// A trait implemented by types that can index into columns of a row.
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///
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/// This cannot be implemented outside of this crate.
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pub trait RowIndex: Sealed {
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#[doc(hidden)]
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fn __idx<T>(&self, columns: &[T]) -> Option<usize>
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where
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T: AsName;
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}
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impl Sealed for usize {}
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impl RowIndex for usize {
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#[inline]
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fn __idx<T>(&self, columns: &[T]) -> Option<usize>
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where
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T: AsName,
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{
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if *self >= columns.len() {
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None
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} else {
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Some(*self)
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}
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}
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}
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impl Sealed for str {}
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impl RowIndex for str {
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#[inline]
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fn __idx<T>(&self, columns: &[T]) -> Option<usize>
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where
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T: AsName,
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{
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if let Some(idx) = columns.iter().position(|d| d.as_name() == self) {
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return Some(idx);
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};
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// FIXME ASCII-only case insensitivity isn't really the right thing to
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// do. Postgres itself uses a dubious wrapper around tolower and JDBC
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// uses the US locale.
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columns
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.iter()
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.position(|d| d.as_name().eq_ignore_ascii_case(self))
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}
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}
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impl<'a, T> Sealed for &'a T where T: ?Sized + Sealed {}
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impl<'a, T> RowIndex for &'a T
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where
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T: ?Sized + RowIndex,
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{
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#[inline]
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fn __idx<U>(&self, columns: &[U]) -> Option<usize>
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where
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U: AsName,
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{
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T::__idx(*self, columns)
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}
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}
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/// A row of data returned from the database by a query.
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pub struct Row {
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statement: Statement,
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body: DataRowBody,
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ranges: Vec<Option<Range<usize>>>,
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}
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impl fmt::Debug for Row {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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f.debug_struct("Row")
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.field("columns", &self.columns())
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.finish()
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}
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}
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impl Row {
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pub(crate) fn new(statement: Statement, body: DataRowBody) -> Result<Row, Error> {
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let ranges = body.ranges().collect().map_err(Error::parse)?;
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Ok(Row {
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statement,
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body,
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ranges,
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})
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}
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/// Returns information about the columns of data in the row.
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pub fn columns(&self) -> &[Column] {
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self.statement.columns()
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}
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/// Determines if the row contains no values.
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pub fn is_empty(&self) -> bool {
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self.len() == 0
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}
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/// Returns the number of values in the row.
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pub fn len(&self) -> usize {
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self.columns().len()
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}
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/// Deserializes a value from the row.
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///
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/// The value can be specified either by its numeric index in the row, or by its column name.
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///
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/// # Panics
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///
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/// Panics if the index is out of bounds or if the value cannot be converted to the specified type.
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pub fn get<'a, I, T>(&'a self, idx: I) -> T
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where
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I: RowIndex + fmt::Display,
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T: FromSql<'a>,
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{
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match self.get_inner(&idx) {
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Ok(ok) => ok,
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Err(err) => panic!("error retrieving column {}: {}", idx, err),
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}
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}
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/// Like `Row::get`, but returns a `Result` rather than panicking.
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pub fn try_get<'a, I, T>(&'a self, idx: I) -> Result<T, Error>
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where
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I: RowIndex + fmt::Display,
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T: FromSql<'a>,
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{
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self.get_inner(&idx)
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}
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fn get_inner<'a, I, T>(&'a self, idx: &I) -> Result<T, Error>
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where
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I: RowIndex + fmt::Display,
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T: FromSql<'a>,
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{
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let idx = match idx.__idx(self.columns()) {
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Some(idx) => idx,
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None => return Err(Error::column(idx.to_string())),
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};
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let ty = self.columns()[idx].type_();
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if !T::accepts(ty) {
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return Err(Error::from_sql(
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Box::new(WrongType::new::<T>(ty.clone())),
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idx,
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));
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}
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FromSql::from_sql_nullable(ty, self.col_buffer(idx)).map_err(|e| Error::from_sql(e, idx))
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}
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/// Get the raw bytes for the column at the given index.
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fn col_buffer(&self, idx: usize) -> Option<&[u8]> {
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let range = self.ranges[idx].to_owned()?;
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Some(&self.body.buffer()[range])
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}
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}
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/// A row of data returned from the database by a simple query.
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pub struct SimpleQueryRow {
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columns: Arc<[String]>,
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body: DataRowBody,
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ranges: Vec<Option<Range<usize>>>,
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}
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impl SimpleQueryRow {
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#[allow(clippy::new_ret_no_self)]
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pub(crate) fn new(columns: Arc<[String]>, body: DataRowBody) -> Result<SimpleQueryRow, Error> {
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let ranges = body.ranges().collect().map_err(Error::parse)?;
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Ok(SimpleQueryRow {
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columns,
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body,
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ranges,
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})
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}
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/// Determines if the row contains no values.
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pub fn is_empty(&self) -> bool {
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self.len() == 0
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}
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/// Returns the number of values in the row.
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pub fn len(&self) -> usize {
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self.columns.len()
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}
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/// Returns a value from the row.
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///
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/// The value can be specified either by its numeric index in the row, or by its column name.
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///
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/// # Panics
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///
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/// Panics if the index is out of bounds or if the value cannot be converted to the specified type.
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pub fn get<I>(&self, idx: I) -> Option<&str>
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where
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I: RowIndex + fmt::Display,
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{
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match self.get_inner(&idx) {
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Ok(ok) => ok,
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Err(err) => panic!("error retrieving column {}: {}", idx, err),
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}
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}
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/// Like `SimpleQueryRow::get`, but returns a `Result` rather than panicking.
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pub fn try_get<I>(&self, idx: I) -> Result<Option<&str>, Error>
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where
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I: RowIndex + fmt::Display,
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{
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self.get_inner(&idx)
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}
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fn get_inner<I>(&self, idx: &I) -> Result<Option<&str>, Error>
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where
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I: RowIndex + fmt::Display,
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{
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let idx = match idx.__idx(&self.columns) {
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Some(idx) => idx,
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None => return Err(Error::column(idx.to_string())),
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};
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let buf = self.ranges[idx].clone().map(|r| &self.body.buffer()[r]);
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FromSql::from_sql_nullable(&Type::TEXT, buf).map_err(|e| Error::from_sql(e, idx))
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}
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}
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