Merge pull request diesel-rs#2652 from henryboisdequin/add-statement-pos-pg

Add the statement position for PostgreSQL errors

Author: weiznich

CHANGELOG.md

@@ -54,6 +54,8 @@ for Rust libraries in [RFC #1105](https://github.com/rust-lang/rfcs/blob/master/
 
 * Added support for `UNION`, `UNION ALL`, `INTERSECT`, `INTERSECT ALL`, `EXCEPT`, `EXCEPT ALL` clauses
 
+* Added the error position for PostgreSQL errors
+
 ### Removed
 
 * All previously deprecated items have been removed.

diesel/src/pg/connection/mod.rs

@@ -185,8 +185,26 @@ mod tests {
     use super::*;
     use crate::dsl::sql;
     use crate::prelude::*;
+    use crate::result::Error::DatabaseError;
     use crate::sql_types::{Integer, VarChar};
 
+    #[test]
+    fn malformed_sql_query() {
+        let connection = connection();
+        let query =
+            crate::sql_query("SELECT not_existent FROM also_not_there;").execute(&connection);
+        if let Err(err) = query {
+            match err {
+                DatabaseError(_, string) => {
+                    assert_eq!(Some(26), string.statement_position());
+                }
+                _ => unreachable!(),
+            }
+        } else {
+            unreachable!();
+        }
+    }
+
     #[test]
     fn prepared_statements_are_cached() {
         let connection = connection();

diesel/src/pg/connection/result.rs

@@ -167,6 +167,11 @@ impl DatabaseErrorInformation for PgErrorInformation {
     fn constraint_name(&self) -> Option<&str> {
         get_result_field(self.0.as_ptr(), ResultField::ConstraintName)
     }
+
+    fn statement_position(&self) -> Option<i32> {
+        let str_pos = get_result_field(self.0.as_ptr(), ResultField::StatementPosition)?;
+        str_pos.parse::<i32>().ok()
+    }
 }
 
 /// Represents valid options to
@@ -182,6 +187,7 @@ enum ResultField {
     TableName = 't' as i32,
     ColumnName = 'c' as i32,
     ConstraintName = 'n' as i32,
+    StatementPosition = 'P' as i32,
 }
 
 fn get_result_field<'a>(res: *mut PGresult, field: ResultField) -> Option<&'a str> {

diesel/src/result.rs

@@ -156,6 +156,10 @@ pub trait DatabaseErrorInformation {
     /// Currently this method will return `None` for all backends other than
     /// PostgreSQL.
     fn constraint_name(&self) -> Option<&str>;
+
+    /// An optional integer indicating an error cursor position as an index into
+    /// the original statement string.
+    fn statement_position(&self) -> Option<i32>;
 }
 
 impl fmt::Debug for dyn DatabaseErrorInformation + Send + Sync {
@@ -168,7 +172,6 @@ impl DatabaseErrorInformation for String {
     fn message(&self) -> &str {
         self
     }
-
     fn details(&self) -> Option<&str> {
         None
     }
@@ -184,6 +187,9 @@ impl DatabaseErrorInformation for String {
     fn constraint_name(&self) -> Option<&str> {
         None
     }
+    fn statement_position(&self) -> Option<i32> {
+        None
+    }
 }
 
 /// Errors which can occur during [`Connection::establish`]