[UIPQB-168] Allow editing queries containing no fields (#196)

CHANGELOG.md

@@ -1,5 +1,9 @@
 # Change history for ui-plugin-query-builder
 
+## IN PROGRESS
+
+* [UIPQB-168](https://folio-org.atlassian.net/browse/UIPQB-168) Allow editing queries containing no fields.
+
 ## [1.2.6](https://github.com/folio-org/ui-plugin-query-builder/tree/v1.2.6) (2024-12-11)
 
 * [UIPQB-128](https://folio-org.atlassian.net/browse/UIPQB-128) Invalid fields handling > Errors when query includes a deleted custom field.

src/QueryBuilder/QueryBuilder/helpers/upgradeInitialValues.js

@@ -7,16 +7,25 @@
  * queries edited/created here are the latest version, as we only have the latest version of entity types available.
  * In the future, it might be neat to send a request to /fqm/migrate if we see initialValues are out of date, but that's
  * outside the scope of UIPQB-125 as we already upgrade queries in the background in mod-lists.
+ *
+ * Returns undefined if there is no initial value (new query).
  */
 export default function upgradeInitialValues(initialValues, entityType) {
   if (!initialValues) {
-    return initialValues;
+    return undefined;
   }
 
   const withoutVersion = { ...initialValues };
 
   delete withoutVersion._version;
 
+  if (Object.keys(withoutVersion).length === 0) {
+    // if the query is {}, treat it as a new query
+    // (all add buttons are displayed on existing rows except for the "new list" state, so if we do
+    // not simulate this state, the user will be unable to add anything)
+    return undefined;
+  }
+
   if (!entityType) {
     return withoutVersion;
   }

src/QueryBuilder/QueryBuilder/helpers/upgradeInitialValues.test.js

@@ -10,13 +10,16 @@ describe('initial values legacy conversion', () => {
     [undefined, undefined],
     [null, {}],
     [undefined, {}],
-    [{}, null],
-    [{}, undefined],
-  ])('ignores initialValues=%s and entityType=%s', (initialValues, entityType) => {
-    expect(upgradeInitialValues(initialValues, entityType)).toStrictEqual(initialValues);
+    [{ _version: '1' }, null],
+    [{ _version: '1' }, undefined],
+    [{ _version: '1' }, null],
+    [{ _version: '1' }, undefined],
+    [{ _version: '1' }, {}],
+  ])('considers initialValues=%s and entityType=%s as a new query', (initialValues, entityType) => {
+    expect(upgradeInitialValues(initialValues, entityType)).toStrictEqual(undefined);
   });
 
-  it.each([{}, { foo: '' }, { bar: '' }, { foo: '', bar: '' }])(
+  it.each([{ foo: '' }, { bar: '' }, { foo: '', bar: '' }])(
     'processes but does not convert non-id columns in %s',
     (values) => {
       expect(upgradeInitialValues(values, ENTITY_TYPE)).toStrictEqual(values);