Better error output

Author: sfackler

src/lib.rs

@@ -134,6 +134,20 @@ impl PostgresDbError {
             routine: map.pop(&('R' as u8)).unwrap()
         }
     }
+
+    fn pretty_error(&self, query: &str) -> ~str {
+        match self.position {
+            Some(Position(pos)) =>
+                format!("{}: {} at position {} in\n{}", self.severity,
+                        self.message, pos, query),
+            Some(InternalPosition { position, query: ref inner_query }) =>
+                format!("{}: {} at position {} in\n{} called from\n{}",
+                        self.severity, self.message, position, *inner_query,
+                        query),
+            None => format!("{}: {} in\n{}", self.severity, self.message,
+                            query)
+        }
+    }
 }
 
 pub struct PostgresConnection {
@@ -328,8 +342,8 @@ impl PostgresConnection {
     pub fn prepare<'a>(&'a self, query: &str) -> NormalPostgresStatement<'a> {
         match self.try_prepare(query) {
             Ok(stmt) => stmt,
-            Err(err) => fail2!("Error preparing \"{}\": {}", query,
-                               err.to_str())
+            Err(err) => fail2!("Error preparing statement:\n{}",
+                               err.pretty_error(query))
         }
     }
 
@@ -385,6 +399,7 @@ impl PostgresConnection {
 
         Ok(NormalPostgresStatement {
             conn: self,
+            query: query.to_owned(),
             name: stmt_name,
             param_types: param_types,
             result_desc: result_desc,
@@ -414,7 +429,8 @@ impl PostgresConnection {
     pub fn update(&self, query: &str, params: &[&ToSql]) -> uint {
         match self.try_update(query, params) {
             Ok(res) => res,
-            Err(err) => fail2!("Error running update: {}", err.to_str())
+            Err(err) => fail2!("Error running update:\n{}",
+                               err.pretty_error(query))
         }
     }
 
@@ -522,6 +538,7 @@ pub trait PostgresStatement {
 
 pub struct NormalPostgresStatement<'self> {
     priv conn: &'self PostgresConnection,
+    priv query: ~str,
     priv name: ~str,
     priv param_types: ~[PostgresType],
     priv result_desc: ~[ResultDescription],
@@ -612,7 +629,8 @@ impl<'self> NormalPostgresStatement<'self> {
             -> PostgresResult<'a> {
         match self.try_lazy_query(row_limit, params) {
             Ok(result) => result,
-            Err(err) => fail2!("Error executing query: {}", err.to_str())
+            Err(err) => fail2!("Error executing query:\n{}",
+                               err.pretty_error(self.query))
         }
     }
 
@@ -654,7 +672,8 @@ impl<'self> PostgresStatement for NormalPostgresStatement<'self> {
     fn update(&self, params: &[&ToSql]) -> uint {
         match self.try_update(params) {
             Ok(count) => count,
-            Err(err) => fail2!("Error running update: {}", err.to_str())
+            Err(err) => fail2!("Error running update\n{}",
+                               err.pretty_error(self.query))
         }
     }