rust-postgres/tokio-postgres/src/query.rs

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2019-07-25 02:18:15 +00:00
use crate::client::{InnerClient, Responses};
use crate::codec::FrontendMessage;
use crate::connection::RequestMessages;
use crate::types::{IsNull, ToSql};
use crate::{Error, Row, Statement};
use futures::{ready, Stream};
use postgres_protocol::message::backend::Message;
use postgres_protocol::message::frontend;
use std::future::Future;
use std::pin::Pin;
use std::sync::Arc;
use std::task::{Context, Poll};
pub async fn query<'a, I>(
client: Arc<InnerClient>,
statement: &Statement,
params: I,
) -> Result<Query, Error>
where
I: IntoIterator<Item = &'a dyn ToSql>,
I::IntoIter: ExactSizeIterator,
{
let responses = start(&client, &statement, params).await?;
Ok(Query {
statement: statement.clone(),
responses,
})
}
pub async fn execute<'a, I>(
client: Arc<InnerClient>,
statement: &Statement,
params: I,
) -> Result<u64, Error>
where
I: IntoIterator<Item = &'a dyn ToSql>,
I::IntoIter: ExactSizeIterator,
{
let mut responses = start(&client, &statement, params).await?;
loop {
match responses.next().await? {
Message::DataRow(_) => {}
Message::CommandComplete(body) => {
let rows = body
.tag()
.map_err(Error::parse)?
.rsplit(' ')
.next()
.unwrap()
.parse()
.unwrap_or(0);
return Ok(rows);
}
Message::EmptyQueryResponse => return Ok(0),
_ => return Err(Error::unexpected_message()),
}
}
}
async fn start<'a, I>(
client: &Arc<InnerClient>,
statement: &Statement,
params: I,
) -> Result<Responses, Error>
where
I: IntoIterator<Item = &'a dyn ToSql>,
I::IntoIter: ExactSizeIterator,
{
let params = params.into_iter();
assert!(
statement.params().len() == params.len(),
"expected {} parameters but got {}",
statement.params().len(),
params.len()
);
let mut buf = vec![];
let mut error_idx = 0;
let r = frontend::bind(
"",
statement.name(),
Some(1),
params.zip(statement.params()).enumerate(),
|(idx, (param, ty)), buf| match param.to_sql_checked(ty, buf) {
Ok(IsNull::No) => Ok(postgres_protocol::IsNull::No),
Ok(IsNull::Yes) => Ok(postgres_protocol::IsNull::Yes),
Err(e) => {
error_idx = idx;
Err(e)
}
},
Some(1),
&mut buf,
);
match r {
Ok(()) => {}
Err(frontend::BindError::Conversion(e)) => return Err(Error::to_sql(e, error_idx)),
Err(frontend::BindError::Serialization(e)) => return Err(Error::encode(e)),
}
frontend::execute("", 0, &mut buf).map_err(Error::encode)?;
frontend::sync(&mut buf);
let mut responses = client.send(RequestMessages::Single(FrontendMessage::Raw(buf)))?;
match responses.next().await? {
Message::BindComplete => {}
_ => return Err(Error::unexpected_message()),
}
Ok(responses)
}
pub struct Query {
statement: Statement,
responses: Responses,
}
impl Stream for Query {
type Item = Result<Row, Error>;
fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
match ready!(self.responses.poll_next(cx)?) {
Message::DataRow(body) => {
Poll::Ready(Some(Ok(Row::new(self.statement.clone(), body)?)))
}
Message::EmptyQueryResponse | Message::CommandComplete(_) => Poll::Ready(None),
Message::ErrorResponse(body) => Poll::Ready(Some(Err(Error::db(body)))),
_ => Poll::Ready(Some(Err(Error::unexpected_message()))),
}
}
}