Fix unable to save field dialog if certain fields are deleted (#2663)

* Fix unable to save field dialog if certain fields are deleted

Implemented solution suggested in issue #2556

* Fix unable to save field dialog if certain fields are deleted

fixed code formating

* Fix unable to save field dialog if certain fields are deleted

Made new functions to check referencelessness.  Added unit test.

CONTRIBUTORS

@@ -139,6 +139,7 @@ Nil Admirari <https://github.com/nihil-admirari>
 Michael Winkworth <github.com/SteelColossus>
 Mateusz Wojewoda <kawa1.11@o2.pl>
 Jarrett Ye <jarrett.ye@outlook.com>
+Sam Waechter <github.com/swektr>
 
 ********************
 

rslib/src/notetype/mod.rs

@@ -551,13 +551,21 @@ impl Notetype {
         fields: HashMap<String, Option<String>>,
         parsed: &mut [(Option<ParsedTemplate>, Option<ParsedTemplate>)],
     ) {
+        let first_remaining_field_name = &self.fields.get(0).unwrap().name;
+        let is_cloze = self.is_cloze();
         for (idx, (q_opt, a_opt)) in parsed.iter_mut().enumerate() {
             if let Some(q) = q_opt {
                 q.rename_and_remove_fields(&fields);
+                if !q.contains_field_replacement() || is_cloze && !q.contains_cloze_replacement() {
+                    q.add_missing_field_replacement(first_remaining_field_name, is_cloze);
+                }
                 self.templates[idx].config.q_format = q.template_to_string();
             }
             if let Some(a) = a_opt {
                 a.rename_and_remove_fields(&fields);
+                if is_cloze && !a.contains_cloze_replacement() {
+                    a.add_missing_field_replacement(first_remaining_field_name, is_cloze);
+                }
                 self.templates[idx].config.a_format = a.template_to_string();
             }
         }
@@ -745,3 +753,73 @@ impl Collection {
         }
     }
 }
+
+// Tests
+//---------------------------------------
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn update_templates_after_removing_crucial_fields() {
+        // Normal Test (all front fields removed)
+        let mut nt_norm = Notetype::default();
+        nt_norm.add_field("baz"); // Fields "foo" and "bar" were removed
+        nt_norm.fields[0].ord = Some(2);
+
+        nt_norm.add_template("Card 1", "front {{foo}}", "back {{bar}}");
+        nt_norm.templates[0].ord = Some(0);
+        let mut parsed = nt_norm.parsed_templates();
+
+        let mut field_map: HashMap<String, Option<String>> = HashMap::new();
+        field_map.insert("foo".to_owned(), None);
+        field_map.insert("bar".to_owned(), None);
+
+        nt_norm.update_templates_for_renamed_and_removed_fields(field_map, &mut parsed);
+        assert_eq!(nt_norm.templates[0].config.q_format, "front {{baz}}");
+        assert_eq!(nt_norm.templates[0].config.a_format, "back ");
+
+        // Cloze Test 1/2 (front and back cloze fields removed)
+        let mut nt_cloze = Notetype {
+            config: Notetype::new_cloze_config(),
+            ..Default::default()
+        };
+        nt_cloze.add_field("baz"); // Fields "foo" and "bar" were removed
+        nt_cloze.fields[0].ord = Some(2);
+
+        nt_cloze.add_template("Card 1", "front {{cloze:foo}}", "back {{cloze:bar}}");
+        nt_cloze.templates[0].ord = Some(0);
+        let mut parsed = nt_cloze.parsed_templates();
+
+        let mut field_map: HashMap<String, Option<String>> = HashMap::new();
+        field_map.insert("foo".to_owned(), None);
+        field_map.insert("bar".to_owned(), None);
+
+        nt_cloze.update_templates_for_renamed_and_removed_fields(field_map, &mut parsed);
+        assert_eq!(nt_cloze.templates[0].config.q_format, "front {{cloze:baz}}");
+        assert_eq!(nt_cloze.templates[0].config.a_format, "back {{cloze:baz}}");
+
+        // Cloze Test 2/2 (only back cloze field is removed)
+        let mut nt_cloze = Notetype {
+            config: Notetype::new_cloze_config(),
+            ..Default::default()
+        };
+        nt_cloze.add_field("foo");
+        nt_cloze.fields[0].ord = Some(0);
+        nt_cloze.add_field("baz");
+        nt_cloze.fields[1].ord = Some(2);
+        // ^ only field "bar" was removed
+
+        nt_cloze.add_template("Card 1", "front {{cloze:foo}}", "back {{cloze:bar}}");
+        nt_cloze.templates[0].ord = Some(0);
+        let mut parsed = nt_cloze.parsed_templates();
+
+        let mut field_map: HashMap<String, Option<String>> = HashMap::new();
+        field_map.insert("bar".to_owned(), None);
+
+        nt_cloze.update_templates_for_renamed_and_removed_fields(field_map, &mut parsed);
+        assert_eq!(nt_cloze.templates[0].config.q_format, "front {{cloze:foo}}");
+        assert_eq!(nt_cloze.templates[0].config.a_format, "back {{cloze:foo}}");
+    }
+}

rslib/src/template.rs

@@ -730,6 +730,30 @@ impl ParsedTemplate {
         let old_nodes = std::mem::take(&mut self.0);
         self.0 = rename_and_remove_fields(old_nodes, fields);
     }
+
+    pub(crate) fn contains_cloze_replacement(&self) -> bool {
+        self.0.iter().any(|node| {
+            matches!(
+                node,
+                ParsedNode::Replacement {key:_, filters} if filters.iter().any(|f| f=="cloze")
+            )
+        })
+    }
+
+    pub(crate) fn contains_field_replacement(&self) -> bool {
+        self.0
+            .iter()
+            .any(|node| matches!(node, ParsedNode::Replacement { key: _, filters: _ }))
+    }
+
+    pub(crate) fn add_missing_field_replacement(&mut self, field_name: &str, is_cloze: bool) {
+        let key = String::from(field_name);
+        let filters = match is_cloze {
+            true => vec![String::from("cloze")],
+            false => Vec::new(),
+        };
+        self.0.push(ParsedNode::Replacement { key, filters });
+    }
 }
 
 fn rename_and_remove_fields(