better error messages

Author: lovasoa

CHANGELOG.md

@@ -12,6 +12,7 @@ This is a bugfix release.
   - adds support for MSSQL's `JSON_ARRAY` and `JSON_OBJECT` functions
   - adds support for PostgreSQL's `JSON_OBJECT(key : value)` and `JSON_OBJECT(key VALUE value)` syntax
   - fixes the parsing of `true` and `false` in Microsoft SQL Server (mssql): they are now correctly parsed as column names, not as boolean values, since mssql does not support boolean literals. This means you may have to replace `TRUE as some_property` with `1 as some_property` in your SQL code when working with mssql.
+- When your SQL contains errors, the error message now displays the precise line(s) number(s) of your file that contain the error.
 
 ## 0.32.0 (2024-12-29)
 

src/webserver/database/error_highlighting.rs

@@ -3,11 +3,18 @@ use std::{
     path::{Path, PathBuf},
 };
 
+use super::sql::{SourceSpan, StmtWithParams};
+
 #[derive(Debug)]
 struct NiceDatabaseError {
+    /// The source file that contains the query.
     source_file: PathBuf,
+    /// The error that occurred.
     db_err: sqlx::error::Error,
+    /// The query that was executed.
     query: String,
+    /// The start location of the query in the source file, if the query was extracted from a larger file.
+    query_position: Option<SourceSpan>,
 }
 
 impl std::fmt::Display for NiceDatabaseError {
@@ -22,12 +29,20 @@ impl std::fmt::Display for NiceDatabaseError {
             let Some(mut offset) = db_err.offset() else {
                 return write!(f, "{}", self.query);
             };
-            for (line_no, line) in self.query.lines().enumerate() {
+            for line in self.query.lines() {
                 if offset > line.len() {
                     offset -= line.len() + 1;
                 } else {
                     highlight_line_offset(f, line, offset);
-                    write!(f, "line {}, character {offset}", line_no + 1)?;
+                    if let Some(query_position) = self.query_position {
+                        let start_line = query_position.start.line;
+                        let end_line = query_position.end.line;
+                        if start_line == end_line {
+                            write!(f, "{}: line {}", self.source_file.display(), start_line)?;
+                        } else {
+                            write!(f, "{}: lines {} to {}", self.source_file.display(), start_line, end_line)?;
+                        }
+                    }
                     break;
                 }
             }
@@ -51,6 +66,22 @@ pub fn display_db_error(
         source_file: source_file.to_path_buf(),
         db_err,
         query: query.to_string(),
+        query_position: None,
+    })
+}
+
+/// Display a database error with a highlighted line and character offset.
+#[must_use]
+pub fn display_stmt_db_error(
+    source_file: &Path,
+    stmt: &StmtWithParams,
+    db_err: sqlx::error::Error,
+) -> anyhow::Error {
+    anyhow::Error::new(NiceDatabaseError {
+        source_file: source_file.to_path_buf(),
+        db_err,
+        query: stmt.query.to_string(),
+        query_position: Some(stmt.query_position),
     })
 }
 

src/webserver/database/execute_queries.rs

@@ -8,6 +8,7 @@ use std::path::Path;
 use std::pin::Pin;
 
 use super::csv_import::run_csv_import;
+use super::error_highlighting::display_stmt_db_error;
 use super::sql::{
     DelayedFunctionCall, ParsedSqlFile, ParsedStatement, SimpleSelectValue, StmtWithParams,
 };
@@ -62,7 +63,7 @@ pub fn stream_query_results_with_conn<'a>(
                     let mut stream = connection.fetch_many(query);
                     let mut error = None;
                     while let Some(elem) = stream.next().await {
-                        let mut query_result = parse_single_sql_result(source_file, &stmt.query, elem);
+                        let mut query_result = parse_single_sql_result(source_file, stmt, elem);
                         if let DbItem::Error(e) = query_result {
                             error = Some(e);
                             break;
@@ -196,7 +197,7 @@ async fn execute_set_variable_query<'a>(
         Ok(None) => None,
         Err(e) => {
             try_rollback_transaction(connection).await;
-            let err = display_db_error(source_file, &statement.query, e);
+            let err = display_stmt_db_error(source_file, statement, e);
             return Err(err);
         }
     };
@@ -257,7 +258,7 @@ async fn take_connection<'a, 'b>(
 #[inline]
 fn parse_single_sql_result(
     source_file: &Path,
-    sql: &str,
+    stmt: &StmtWithParams,
     res: sqlx::Result<Either<AnyQueryResult, AnyRow>>,
 ) -> DbItem {
     match res {
@@ -272,7 +273,7 @@ fn parse_single_sql_result(
             DbItem::FinishedQuery
         }
         Err(err) => {
-            let nice_err = display_db_error(source_file, sql, err);
+            let nice_err = display_stmt_db_error(source_file, stmt, err);
             DbItem::Error(nice_err)
         }
     }

src/webserver/database/sql.rs

@@ -70,6 +70,8 @@ impl AsyncFromStrWithState for ParsedSqlFile {
 pub(super) struct StmtWithParams {
     /// The SQL query with placeholders for parameters.
     pub query: String,
+    /// The line and column of the first token in the query.
+    pub query_position: SourceSpan,
     /// Parameters that should be bound to the query.
     /// They can contain functions that will be called before the query is executed,
     /// the result of which will be bound to the query.
@@ -82,6 +84,20 @@ pub(super) struct StmtWithParams {
     pub json_columns: Vec<String>,
 }
 
+/// A location in the source code.
+#[derive(Debug, PartialEq, Clone, Copy)]
+pub(super) struct SourceSpan {
+    pub start: SourceLocation,
+    pub end: SourceLocation,
+}
+
+/// A location in the source code.
+#[derive(Debug, PartialEq, Clone, Copy)]
+pub(super) struct SourceLocation {
+    pub line: usize,
+    pub column: usize,
+}
+
 #[derive(Debug)]
 pub(super) enum ParsedStatement {
     StmtWithParams(StmtWithParams),
@@ -165,12 +181,27 @@ fn parse_single_statement(
     log::debug!("Final transformed statement: {stmt}");
     Some(ParsedStatement::StmtWithParams(StmtWithParams {
         query,
+        query_position: extract_query_start(&stmt),
         params,
         delayed_functions,
         json_columns,
     }))
 }
 
+fn extract_query_start(stmt: &impl Spanned) -> SourceSpan {
+    let location = stmt.span();
+    SourceSpan {
+        start: SourceLocation {
+            line: usize::try_from(location.start.line).unwrap_or(0),
+            column: usize::try_from(location.start.column).unwrap_or(0),
+        },
+        end: SourceLocation {
+            line: usize::try_from(location.end.line).unwrap_or(0),
+            column: usize::try_from(location.end.column).unwrap_or(0),
+        },
+    }
+}
+
 fn syntax_error(err: ParserError, parser: &Parser, sql: &str) -> ParsedStatement {
     let location = parser.peek_token_no_skip().span;
     ParsedStatement::Error(anyhow::Error::from(err).context(format!(
@@ -426,6 +457,7 @@ fn extract_set_variable(
                 variable,
                 StmtWithParams {
                     query: select_stmt.to_string(),
+                    query_position: extract_query_start(&select_stmt),
                     params: std::mem::take(params),
                     delayed_functions,
                     json_columns,