Only detect deletions where attribute set to null

For fields where an empty value is represented by null,
it is easy to detect deletions. For other fields e.g. arrays,
more complex logic needs to be developed later

app/src/api/dataAccess/__mocks__/editHistory.ts

@@ -18,7 +18,7 @@ mockEditHistory.__setHistory = function(mockHistoryData: EditHistoryEntry[]) {
 };
 
 function hasDeletions(json) {
-    return Object.values(json).some(x => x === null || (Array.isArray(x) && x.length === 0))
+    return Object.values(json).some(x => x === null);
 }
 
 mockEditHistory.getHistoryAfterId = function(id: string, count: number, filterDeletions: boolean): Promise<EditHistoryEntry[]> {

app/src/api/dataAccess/editHistory.ts

@@ -14,7 +14,7 @@ const baseQuery = `
         JOIN users ON logs.user_id = users.user_id`;
 
 const deletionCondition = `
-    EXISTS (SELECT * from jsonb_each(forward_patch) WHERE value IN ('null', '[]'))
+    EXISTS (SELECT * from jsonb_each(forward_patch) WHERE value = 'null' )
 `;
 
 export function getHistoryAfterId(id: string, count: number, filterDeletions: boolean = false): Promise<EditHistoryEntry[]> {