Improve land use processing backend

app/package-lock.json

@@ -1097,6 +1097,12 @@
         "@types/geojson": "*"
       }
     },
+    "@types/lodash": {
+      "version": "4.14.149",
+      "resolved": "https://registry.npmjs.org/@types/lodash/-/lodash-4.14.149.tgz",
+      "integrity": "sha512-ijGqzZt/b7BfzcK9vTrS6MFljQRPn5BFWOx8oE0GYxribu6uV+aA9zZuXI1zc/etK9E8nrgdoF2+LgUw7+9tJQ==",
+      "dev": true
+    },
     "@types/mapbox__sphericalmercator": {
       "version": "1.1.3",
       "resolved": "https://registry.npmjs.org/@types/mapbox__sphericalmercator/-/mapbox__sphericalmercator-1.1.3.tgz",

app/package.json

@@ -42,6 +42,7 @@
     "@types/express": "^4.17.0",
     "@types/express-session": "^1.15.13",
     "@types/jest": "^24.0.17",
+    "@types/lodash": "^4.14.149",
     "@types/mapbox__sphericalmercator": "^1.1.3",
     "@types/node": "^8.10.52",
     "@types/nodemailer": "^6.2.1",

app/src/api/services/building.ts

@@ -158,7 +158,7 @@ async function getBuildingUPRNsById(id: number) {
 async function saveBuilding(buildingId: number, building: any, userId: string) { // TODO add proper building type
     try {
         return await updateBuildingData(buildingId, userId, async () => {
-            const processedBuilding = await processBuildingUpdate(building);
+            const processedBuilding = await processBuildingUpdate(buildingId, building);
             
             // remove read-only fields from consideration
             delete processedBuilding.building_id;

app/src/api/services/domainLogic/currentLandUseClassifications.ts

@@ -1,48 +1,73 @@
-import db from '../../../db';
+import * as _ from 'lodash';
-import { getBuildingById, getCurrentBuildingDataById } from '../building';
 
-export async function processCurrentLandUseClassifications(building: any): Promise<any> {
+import db from '../../../db';
+import { isNullishOrEmpty } from '../../../helpers';
+import { getCurrentBuildingDataById } from '../building';
+
+export async function processCurrentLandUseClassifications(buildingId: number, building: any): Promise<any> {
+    let updateData = _.pick(await getCurrentBuildingDataById(buildingId), [
+        'current_landuse_class',
+        'current_landuse_group',
+        'current_landuse_order'
+    ]);
+    
+    updateData = Object.assign({}, updateData, getClearValues(building));
     
     const updateFrom = getUpdateStartingStage(building);
-    const currentData = await getCurrentBuildingDataById(building.building_id);
-
     if(updateFrom === 'class') {
-        building.current_landuse_group = await deriveGroupFromClass(building.current_landuse_class);
+        updateData.current_landuse_class = building.current_landuse_class;
-        building.current_landuse_order = await deriveOrderFromGroup(building.current_landuse_group);
+        updateData.current_landuse_group = await deriveGroupFromClass(updateData.current_landuse_class);
+        updateData.current_landuse_order = await deriveOrderFromGroup(updateData.current_landuse_group);
     } else if (updateFrom === 'group') {
-        if(currentData.current_landuse_class == undefined) {
+        if (isNullishOrEmpty(updateData.current_landuse_class)) {
-            building.current_landuse_order = await deriveOrderFromGroup(building.current_landuse_group);
+            updateData.current_landuse_group = building.current_landuse_group;
+            updateData.current_landuse_order = await deriveOrderFromGroup(building.current_landuse_group);
         } else {
-            delete building.current_landuse_group;
+            throw new Error('Trying to update current_landuse_group field but a more detailed field (current_landuse_class) is already filled');
-            delete building.current_landuse_order;
         }
     } else if (updateFrom === 'order') {
-        if(currentData.current_landuse_class == undefined && currentData.current_landuse_group == undefined) {
+        if (isNullishOrEmpty(updateData.current_landuse_class) && isNullishOrEmpty(updateData.current_landuse_group)) {
-            // do nothing, building.current_landuse_order is already correctly set and can be used for the update
+            updateData.current_landuse_order = building.current_landuse_order;
         } else {
-            delete building.current_landuse_order;
+            throw new Error('Trying to update current_landuse_order field but a more detailed field (current_landuse_class or current_landuse_group) is already filled');
         }
     }
 
-    return building;
+    return Object.assign({}, building, updateData);
 }
 
+function getClearValues(building) {
+    const clearValues: any = {};
+    if(building.hasOwnProperty('current_landuse_class') && isNullishOrEmpty(building.current_landuse_class)) {
+        clearValues.current_landuse_class = [];
+    }
+    if(building.hasOwnProperty('current_landuse_group') && isNullishOrEmpty(building.current_landuse_group)) {
+        clearValues.current_landuse_group = [];
+    }
+    if(building.hasOwnProperty('current_landuse_order') && isNullishOrEmpty(building.current_landuse_order)) {
+        clearValues.current_landuse_order = null;
+    }
+
+    return clearValues;
+}
 /**
  * Choose which level of the land use classification hierarchy the update should start from.
  * @param building 
  */
 function getUpdateStartingStage(building) {
-    if(building.hasOwnProperty('current_landuse_class')) {
+    if(building.hasOwnProperty('current_landuse_class') && !isNullishOrEmpty(building.current_landuse_class)) {
         return 'class';
-    } else if(building.hasOwnProperty('current_landuse_group')) {
+    } else if(building.hasOwnProperty('current_landuse_group') && !isNullishOrEmpty(building.current_landuse_group)) {
         return 'group';
-    } else if(building.hasOwnProperty('current_landuse_order')) {
+    } else if(building.hasOwnProperty('current_landuse_order') && !isNullishOrEmpty(building.current_landuse_order)) {
         return 'order';
     } else return 'none';
 }
 
-function deriveGroupFromClass(classes: string[]): Promise<string[]> {
+async function deriveGroupFromClass(classes: string[]): Promise<string[]> {
-    return db.many(
+    if (classes.length === 0) return [];
+
+    return (await db.many(
         `
         SELECT DISTINCT parent.description
         FROM reference_tables.buildings_landuse_group AS parent
@@ -51,11 +76,13 @@ function deriveGroupFromClass(classes: string[]): Promise<string[]> {
         WHERE child.description IN ($1:csv)
         ORDER BY parent.description`,
         [classes]
-    );
+    )).map(x => x.description);
 }
 
 async function deriveOrderFromGroup(groups: string[]): Promise<string> {
-    const orders = await db.many(
+    if(groups.length === 0) return null;
+
+    const orders = (await db.many(
         `
         SELECT DISTINCT parent.description
         FROM reference_tables.buildings_landuse_order AS parent
@@ -65,7 +92,7 @@ async function deriveOrderFromGroup(groups: string[]): Promise<string> {
         ORDER BY parent.description
         `,
         [groups]
-    );
+    )).map(x => x.description);
 
     if(orders.length === 1) {
         return orders[0];

app/src/api/services/domainLogic/processBuildingUpdate.ts

@@ -2,9 +2,9 @@ import { hasAnyOwnProperty } from '../../../helpers';
 
 import { processCurrentLandUseClassifications } from './currentLandUseClassifications';
 
-export async function processBuildingUpdate<T>(building: T): Promise<T> {
+export async function processBuildingUpdate(buildingId: number, building: any): Promise<any> {
     if(hasAnyOwnProperty(building, ['current_landuse_class', 'current_landuse_group', 'current_landuse_order'])) {
-        building = await processCurrentLandUseClassifications(building);
+        building = await processCurrentLandUseClassifications(buildingId, building);
     }
 
     return building;

app/src/helpers.ts

@@ -27,3 +27,10 @@ export function parseJsonOrDefault(jsonString: string) {
 export function hasAnyOwnProperty(obj: {}, keys: string[]) {
     return keys.some(k => obj.hasOwnProperty(k));
 }
+
+export function isNullishOrEmpty(obj: any) {
+    return obj == undefined || isEmptyArray(obj);
+}
+export function isEmptyArray(obj: any) {
+    return Array.isArray(obj) && obj.length === 0;
+}