Fix bug with column position (#69)

* Fix bug with column position

* Update CHANGELOG

CHANGELOG.md

@@ -12,6 +12,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### ⚙️ Changed
 
 ### 🛠 Fixed
+- Fix bug with dropped columns [#69](https://github.com/datanymizer/datanymizer/pull/69)
+  ([@evgeniy-r](https://github.com/evgeniy-r))
 - Update crates with security issues [#65](https://github.com/datanymizer/datanymizer/pull/65)
   ([@evgeniy-r](https://github.com/evgeniy-r))
 - Add proper escaping after the transformation for Postgres [#60](https://github.com/datanymizer/datanymizer/pull/60)

datanymizer_dumper/src/postgres/table.rs

@@ -80,8 +80,10 @@ impl PgTable {
 
     pub fn set_columns(&mut self, columns: Vec<PgColumn>) {
         let mut map: HashMap<String, usize> = HashMap::with_capacity(columns.len());
-        for column in &columns {
-            map.insert(column.name.clone(), (column.position - 1) as usize);
+        let mut column_refs: Vec<_> = columns.iter().collect();
+        column_refs.sort_by_key(|c| c.position);
+        for (i, column) in column_refs.iter().enumerate() {
+            map.insert(column.name.clone(), i);
         }
 
         self.column_indexes = map;
@@ -240,8 +242,10 @@ mod tests {
             inner_type: Some(0),
         };
         let col3 = PgColumn {
-            position: 3,
-            name: String::from("col3"),
+            // Column positions in Postgres are not always in sequence
+            // (e.g., when we have dropped some column).
+            position: 4,
+            name: String::from("col4"),
             data_type: String::new(),
             inner_type: Some(0),
         };
@@ -253,7 +257,7 @@ mod tests {
         assert_eq!(table.column_indexes.len(), 3);
         assert_eq!(table.column_indexes["col1"], 0);
         assert_eq!(table.column_indexes["col2"], 1);
-        assert_eq!(table.column_indexes["col3"], 2);
+        assert_eq!(table.column_indexes["col4"], 2);
     }
 
     mod query_to {