feat(spin_sdk::pg): Improve pg type's conversion in Rust SDK

- Add conversion support for: int16, int32, int64, floating32,
floating64, binary, boolean;
- Add support for nullable variants;
- Introduce spin_sdk::pg::Error;

Signed-off-by: Konstantin Shabanov <mail@etehtsea.me>

crates/outbound-pg/src/lib.rs

@@ -139,8 +139,7 @@ fn convert_data_type(pg_type: &Type) -> DbDataType {
         Type::INT2 => DbDataType::Int16,
         Type::INT4 => DbDataType::Int32,
         Type::INT8 => DbDataType::Int64,
-        Type::TEXT => DbDataType::Str,
-        Type::VARCHAR => DbDataType::Str,
+        Type::TEXT | Type::VARCHAR | Type::BPCHAR => DbDataType::Str,
         _ => {
             tracing::debug!("Couldn't convert Postgres type {} to WIT", pg_type.name(),);
             DbDataType::Other
@@ -208,17 +207,10 @@ fn convert_entry(row: &Row, index: usize) -> Result<DbValue, tokio_postgres::Err
                 None => DbValue::DbNull,
             }
         }
-        &Type::TEXT => {
-            let value: Option<&str> = row.try_get(index)?;
+        &Type::TEXT | &Type::VARCHAR | &Type::BPCHAR => {
+            let value: Option<String> = row.try_get(index)?;
             match value {
-                Some(v) => DbValue::Str(v.to_owned()),
-                None => DbValue::DbNull,
-            }
-        }
-        &Type::VARCHAR => {
-            let value: Option<&str> = row.try_get(index)?;
-            match value {
-                Some(v) => DbValue::Str(v.to_owned()),
+                Some(v) => DbValue::Str(v),
                 None => DbValue::DbNull,
             }
         }

examples/rust-outbound-pg/db/testdata.sql

@@ -2,7 +2,8 @@ CREATE TABLE articletest (
    id integer GENERATED BY DEFAULT AS IDENTITY PRIMARY KEY,
    title varchar(40) NOT NULL,
    content text NOT NULL,
-   authorname varchar(40) NOT NULL
+   authorname varchar(40) NOT NULL,
+   coauthor text
 );
 
 INSERT INTO articletest (title, content, authorname) VALUES

examples/rust-outbound-pg/src/lib.rs

@@ -1,9 +1,9 @@
 #![allow(dead_code)]
-use anyhow::{anyhow, Result};
+use anyhow::Result;
 use spin_sdk::{
     http::{Request, Response},
     http_component,
-    pg,
+    pg::{self, Decode},
 };
 
 // The environment variable set in `spin.toml` that points to the
@@ -16,22 +16,25 @@ struct Article {
     title: String,
     content: String,
     authorname: String,
+    coauthor: Option<String>,
 }
 
 impl TryFrom<&pg::Row> for Article {
     type Error = anyhow::Error;
 
     fn try_from(row: &pg::Row) -> Result<Self, Self::Error> {
-        let id: i32 = (&row[0]).try_into()?;
-        let title: String = (&row[1]).try_into()?;
-        let content: String = (&row[2]).try_into()?;
-        let authorname: String = (&row[3]).try_into()?;
+        let id = i32::decode(&row[0])?;
+        let title = String::decode(&row[1])?;
+        let content = String::decode(&row[2])?;
+        let authorname = String::decode(&row[3])?;
+        let coauthor = Option::<String>::decode(&row[4])?;
 
         Ok(Self {
             id,
             title,
             content,
             authorname,
+            coauthor,
         })
     }
 }
@@ -51,9 +54,8 @@ fn process(req: Request) -> Result<Response> {
 fn read(_req: Request) -> Result<Response> {
     let address = std::env::var(DB_URL_ENV)?;
 
-    let sql = "SELECT id, title, content, authorname FROM articletest";
-    let rowset = pg::query(&address, sql, &[])
-        .map_err(|e| anyhow!("Error executing Postgres query: {:?}", e))?;
+    let sql = "SELECT id, title, content, authorname, coauthor FROM articletest";
+    let rowset = pg::query(&address, sql, &[])?;
 
     let column_summary = rowset
         .columns
@@ -89,16 +91,14 @@ fn write(_req: Request) -> Result<Response> {
     let address = std::env::var(DB_URL_ENV)?;
 
     let sql = "INSERT INTO articletest (title, content, authorname) VALUES ('aaa', 'bbb', 'ccc')";
-    let nrow_executed =
-        pg::execute(&address, sql, &[]).map_err(|_| anyhow!("Error execute pg command"))?;
+    let nrow_executed = pg::execute(&address, sql, &[])?;
 
     println!("nrow_executed: {}", nrow_executed);
 
     let sql = "SELECT COUNT(id) FROM articletest";
-    let rowset = pg::query(&address, sql, &[])
-        .map_err(|e| anyhow!("Error executing Postgres query: {:?}", e))?;
+    let rowset = pg::query(&address, sql, &[])?;
     let row = &rowset.rows[0];
-    let count: i64 = (&row[0]).try_into()?;
+    let count = i64::decode(&row[0])?;
     let response = format!("Count: {}\n", count);
 
     Ok(http::Response::builder()
@@ -111,12 +111,10 @@ fn pg_backend_pid(_req: Request) -> Result<Response> {
     let sql = "SELECT pg_backend_pid()";
 
     let get_pid = || {
-        let rowset = pg::query(&address, sql, &[])
-            .map_err(|e| anyhow!("Error executing Postgres query: {:?}", e))?;
-
+        let rowset = pg::query(&address, sql, &[])?;
         let row = &rowset.rows[0];
 
-        i32::try_from(&row[0])
+        i32::decode(&row[0])
     };
 
     assert_eq!(get_pid()?, get_pid()?);

sdk/rust/Cargo.toml

@@ -13,4 +13,5 @@ bytes = "1"
 form_urlencoded = "1.0"
 http = "0.2"
 spin-macro = { path = "macro" }
+thiserror = "1.0.37"
 wit-bindgen-rust = { git = "https://github.com/bytecodealliance/wit-bindgen", rev = "cb871cfa1ee460b51eb1d144b175b9aab9c50aba" }