feat(expression-builder): allow for empty arrays and objects

* docs(todo): update to post-v3 todos

* feat(expression-builder): allow for empty arrays, Sets and objects

* feat(expression-builder): revert for sets

Author: michaelwittwer

src/dynamo/expression/condition-expression-builder.spec.ts

@@ -42,11 +42,21 @@ describe('expressions', () => {
       {},
       [],
       { blub: undefined, other: undefined },
+      { emptyArr: [] },
       new Set(arr),
     ]
 
     const filteredObj = deepFilter(obj, (item) => item !== undefined)
-    expect(filteredObj).toEqual([{ street: 'street', zip: 1524 }, [{ age: 25 }], new Set([arr[0], arr[1]])])
+    expect(filteredObj).toEqual([
+      { street: 'street', zip: 1524 },
+      [{ age: 25 }],
+      [{}],
+      {},
+      [],
+      {},
+      { emptyArr: [] },
+      new Set([arr[0], arr[1]]),
+    ])
   })
 
   it('use property metadata', () => {

src/dynamo/expression/condition-expression-builder.ts

@@ -40,7 +40,7 @@ type BuildFilterFn = (
  */
 
 /**
- * Will walk the object tree recursively and removes all items which do not satisfy the filterFn
+ * Will walk the object tree recursively and removes all items that do not satisfy the filterFn
  * @param obj
  * @param {(value: any) => boolean} filterFn
  * @returns {any}
@@ -56,7 +56,7 @@ export function deepFilter(obj: any, filterFn: (value: any) => boolean): any {
       }
     })
 
-    return returnArr.length ? returnArr : null
+    return returnArr
   } else if (obj instanceof Set) {
     const returnArr: any[] = []
     Array.from(obj).forEach((i) => {
@@ -80,7 +80,7 @@ export function deepFilter(obj: any, filterFn: (value: any) => boolean): any {
       }
     }
 
-    return Object.keys(returnObj).length ? returnObj : null
+    return returnObj
   } else {
     if (filterFn(obj)) {
       return obj

src/dynamo/expression/prepare-and-add-update-expressions.function.ts

@@ -21,7 +21,7 @@ export function prepareAndAddUpdateExpressions(
   if (updateDefFns && updateDefFns.length) {
     const sortedByActionKeyWord: Map<UpdateActionKeyword, UpdateExpression[]> = updateDefFns
       .map((updateDefFn) => {
-        // TODO v3: investigate on how to remove any
+        // TODO post-v3:: investigate on how to remove any
         // tslint:disable-next-line:no-unnecessary-type-assertion
         return updateDefFn(params.ExpressionAttributeNames as any, metadata)
       })

src/dynamo/expression/update-expression-builder.spec.ts

@@ -81,6 +81,18 @@ describe('buildUpdateExpression', () => {
       })
     })
 
+    describe('should build set expression for empty collection', () => {
+      it('array', () => {
+        const exp = buildUpdateExpression('addresses', op, [[]], [], metaDataU)
+        expect(exp).toEqual({
+          attributeNames: { '#addresses': 'addresses' },
+          attributeValues: { ':addresses': { L: [] } },
+          statement: '#addresses = :addresses',
+          type: 'SET',
+        })
+      })
+    })
+
     it('should build set expression for number at document path', () => {
       const exp = buildUpdateExpression('numberValues[0]', op, [23], [], metaDataU)
       expect(exp).toEqual({
@@ -144,7 +156,7 @@ describe('buildUpdateExpression', () => {
     const op = new UpdateActionDef('DELETE', 'removeFromSet')
 
     it('should build the expression', () => {
-      const exp = buildUpdateExpression('topics', op, [['val1', 'val2']], [], metaDataU)
+      const exp = buildUpdateExpression('topics', op, [new Set(['val1', 'val2'])], [], metaDataU)
       expect(exp).toEqual({
         attributeNames: { '#topics': 'topics' },
         attributeValues: { ':topics': { SS: ['val1', 'val2'] } },

src/dynamo/expression/update-expression-builder.ts

@@ -36,7 +36,7 @@ export function buildUpdateExpression(
   existingValueNames: string[] | undefined,
   metadata: Metadata<any> | undefined,
 ): UpdateExpression {
-  // metadata get rid of undefined values
+  // get rid of undefined values
   values = deepFilter(values, (value) => value !== undefined) || []
 
   // load property metadata if model metadata was provided

src/dynamo/request/get/get.request.ts

@@ -52,7 +52,7 @@ export class GetRequest<T, T2 extends Partial<T> = T> extends StandardRequest<
       .getItem(this.params)
       .then(promiseTap((response) => this.logger.debug('response', response)))
       .then((getItemResponse) => {
-        // TODO v3: investigate on how to remove any
+        // TODO post-v3: investigate on how to remove any
         // tslint:disable-next-line:no-unnecessary-type-assertion
         const response: GetResponse<T2> = { ...(getItemResponse as any) }