fix: fix that child entity updates referencing non-existant IDs would add new child entities

Previously, we did not check whether the child entities we wanted to update
actually existed.

The bug has been introduced with the new dict-based child entity update
implementation.

Author: Yogu

spec/regression/logistics/tests/update-child-entities-dict.graphql

@@ -61,6 +61,9 @@ mutation updateMultiple {
                 { id: "id_test_0007", itemNumber: "updated07" }
                 { id: "id_test_0008", itemNumber: "updated08" }
                 { id: "id_test_0009", itemNumber: "updated09" }
+                # make sure this one does not end up in the list
+                # (the initial implementation of the dict-based update had a bug that it was)
+                { id: "nonexistant", itemNumber: "updated10" }
             ]
         }
     ) {

spec/regression/logistics/tests/update-child-entities.graphql

@@ -61,6 +61,9 @@ mutation updateMultiple {
                 { id: "id_test_0007", itemNumber: "updated07" }
                 { id: "id_test_0008", itemNumber: "updated08" }
                 { id: "id_test_0009", itemNumber: "updated09" }
+                # make sure this one does not end up in the list
+                # (the initial implementation of the dict-based update had a bug that it was)
+                { id: "nonexistant", itemNumber: "updated10" }
             ]
         }
     ) {

src/database/arangodb/aql-generator.ts

@@ -853,9 +853,13 @@ register(UpdateChildEntitiesQueryNode, (node, context) => {
         ),
         aql`})`,
 
-        // sort by the __index we stored, and unpack the dictionary into a list again
+        // sort by the __index we stored,
+        // filter out objects that were included in node.updates() but did not actually exist in node.originalList
+        // (for them, __index is not set)
+        // and unpack the dictionary into a list again
         aql`FOR ${itemVar}`,
         aql`IN VALUES(${updatedDictVar})`,
+        aql`FILTER ${itemVar}.__index != null`,
         aql`SORT ${itemVar}.__index`,
         aql`RETURN UNSET(${itemVar}, '__index')`,
     );

src/database/inmemory/js-generator.ts

@@ -528,7 +528,11 @@ register(UpdateChildEntitiesQueryNode, (node, context) => {
         // could be a complex expression, and we're using it multiple times -> store in a variable
         js`const ${itemsVar} = ${processNode(node.originalList, context)}`,
 
-        // add a __index property to each item so we can sort by this later
+        // the aql implementation needs an __index property to sort the object after applying
+        // the updates. the js implementation does not need to sort because {...obj, a: ...}
+        // keeps the order of properties in obj. However, we still need to filter out updates
+        // for which there are no items in originalList. To stay close to the aql implementation,
+        // we just also set an __index here.
         // regular field names cannot start with an underscore, so we're safe to use __index as a
         // temporary property to store the index of the child entity in the list
         // convert the list into a dict object like { 'id1': { ...}, 'id2': { ... } }
@@ -566,8 +570,10 @@ register(UpdateChildEntitiesQueryNode, (node, context) => {
         ),
         js`};`,
 
-        // sort by the __index we stored, and unpack the dictionary into a list again
-        js`return Object.values(${updatedDictVar}).map(({ __index, ...${itemVar} }) => ${itemVar});`,
+        // filter out objects that were included in node.updates() but did not actually exist in node.originalList
+        // (for them, __index is not set)
+        // and unpack the dictionary into a list again
+        js`return Object.values(${updatedDictVar}).filter(({ __index }) => __index !== undefined).map(({ __index, ...${itemVar} }) => ${itemVar});`,
     );
 });