Return more RowDescription fields

As we are trying to match client-side behaviour with node-postgres we
need to return this fields as well because node-postgres returns them.

Author: kelvich

tokio-postgres/src/client.rs

@@ -439,8 +439,10 @@ impl Client {
         if let Some(row_description) = row_description {
             let mut it = row_description.fields();
             while let Some(field) = it.next().map_err(Error::parse)? {
+                // NB: for some types that function may send a query to the server. At least in
+                // raw text mode we don't need that info and can skip this.
                 let type_ = get_type(&self.inner, field.type_oid()).await?;
-                let column = Column::new(field.name().to_string(), type_);
+                let column = Column::new(field.name().to_string(), type_, field);
                 columns.push(column);
             }
         }

tokio-postgres/src/statement.rs

@@ -2,7 +2,10 @@ use crate::client::InnerClient;
 use crate::codec::FrontendMessage;
 use crate::connection::RequestMessages;
 use crate::types::Type;
-use postgres_protocol::message::frontend;
+use postgres_protocol::{
+    message::{backend::Field, frontend},
+    Oid,
+};
 use postgres_types::Format;
 use std::{
     fmt,

tokio-postgres/tests/test/main.rs

@@ -351,6 +351,31 @@ async fn command_tag() {
     assert_eq!(row_stream.command_tag(), Some("SELECT 3".to_string()));
 }
 
+#[tokio::test]
+async fn column_extras() {
+    let client = connect("user=postgres").await;
+
+    let rows: Vec<tokio_postgres::Row> = client
+        .query_raw_txt("select relacl, relname from pg_class limit 1", [])
+        .await
+        .unwrap()
+        .try_collect()
+        .await
+        .unwrap();
+
+    let column = rows[0].columns().get(1).unwrap();
+    assert_eq!(column.name(), "relname");
+    assert_eq!(column.type_(), &Type::NAME);
+
+    assert!(column.table_oid() > 0);
+    assert_eq!(column.column_id(), 2);
+    assert_eq!(column.format(), 0);
+
+    assert_eq!(column.type_oid(), 19);
+    assert_eq!(column.type_size(), 64);
+    assert_eq!(column.type_modifier(), -1);
+}
+
 #[tokio::test]
 async fn custom_composite() {
     let client = connect("user=postgres").await;