keep bc cursors after view change

Author: aegorov

src/actions/actions.ts

@@ -585,6 +585,7 @@ export class ActionPayloadTypes {
     bcChangeCursors: {
         cursorsMap: Record<string, string>
         keepDelta?: boolean
+        resetChildren?: boolean
     } = z
 
     /**

src/epics/data.ts

@@ -92,8 +92,11 @@ export const bcSelectRecord: Epic = (action$, store) =>
                 keepDelta: action.payload.keepDelta
             })
         })
+
         return Observable.concat(
-            Observable.of($do.bcChangeCursors({ cursorsMap: { [bcName]: cursor }, keepDelta: action.payload.keepDelta })),
+            Observable.of(
+                $do.bcChangeCursors({ cursorsMap: { [bcName]: cursor }, keepDelta: action.payload.keepDelta, resetChildren: true })
+            ),
             Observable.of($do.bcFetchRowMeta({ widgetName: '', bcName })),
             fetchChildrenBcData
         )

src/epics/data/bcFetchData.ts

@@ -213,12 +213,14 @@ function getCursorChange(data: DataItem[], action: ActionType, prevCursor: strin
     const { bcName } = action.payload
     const { keepDelta } = (action as ActionsMap[typeof types.bcFetchDataRequest]).payload
     const newCursor = data[0]?.id
+    const prevCursorData = data.some(i => i.id === prevCursor)
     const changeCurrentCursor = Observable.of<AnyAction>(
         $do.bcChangeCursors({
             cursorsMap: {
-                [bcName]: data.some(i => i.id === prevCursor) ? prevCursor : newCursor
+                [bcName]: prevCursorData ? prevCursor : newCursor
             },
-            keepDelta: isHierarchy || keepDelta
+            keepDelta: isHierarchy || keepDelta,
+            resetChildren: !prevCursorData
         })
     )
     return changeCurrentCursor

src/reducers/screen.ts

@@ -95,7 +95,7 @@ export function screen(state = initialState, action: AnyAction, store: Store): S
             )
                 .filter(bcName => state.bo.bc[bcName])
                 .forEach(bcName => {
-                    newBcs[bcName] = { ...state.bo.bc[bcName], page: 1 }
+                    newBcs[bcName] = { ...state.bo.bc[bcName] }
                 })
             return {
                 ...state,
@@ -210,19 +210,21 @@ export function screen(state = initialState, action: AnyAction, store: Store): S
         case types.bcChangeCursors: {
             const newCursors: Record<string, BcMetaState> = {}
             const newCache: Record<string, string> = {}
+            const { resetChildren } = action.payload
             Object.entries(action.payload.cursorsMap).forEach(entry => {
                 const [bcName, cursor] = entry
                 newCursors[bcName] = { ...state.bo.bc[bcName], cursor }
                 newCache[bcName] = cursor
             })
             // Also reset cursors of all children of requested BCs
             const changedParents = Object.values(newCursors).map(bc => `${bc.url}/:id`)
-            Object.values(state.bo.bc).forEach(bc => {
-                if (changedParents.some(item => bc.url.includes(item))) {
-                    newCursors[bc.name] = { ...state.bo.bc[bc.name], cursor: null }
-                    newCache[bc.name] = null
-                }
-            })
+            resetChildren &&
+                Object.values(state.bo.bc).forEach(bc => {
+                    if (changedParents.some(item => bc.url.includes(item))) {
+                        newCursors[bc.name] = { ...state.bo.bc[bc.name], cursor: null, page: 1 }
+                        newCache[bc.name] = null
+                    }
+                })
             return {
                 ...state,
                 bo: {