refactor(utils): replace isPresent with isNil

isPresent is a misleading name (see #704) as it considers options
specified as null to not be present.

src/auth/auth.ts

@@ -79,12 +79,12 @@ export class AngularFireAuth extends ReplaySubject<FirebaseAuthState> {
     }
     config = this._mergeConfigs(config);
 
-    if (!utils.isPresent(config.method)) {
+    if (utils.isNil(config.method)) {
       return this._reject('You must provide a login method');
     }
     let providerMethods = [AuthMethods.Popup, AuthMethods.Redirect, AuthMethods.OAuthToken];
     if (providerMethods.indexOf(config.method) != -1) {
-      if (!utils.isPresent(config.provider)) {
+      if (utils.isNil(config.provider)) {
         return this._reject('You must include a provider to use this auth method.');
       }
     }

src/auth/firebase_sdk_auth_backend.ts

@@ -3,7 +3,7 @@ import { Injectable, Inject } from '@angular/core';
 import { Observable } from 'rxjs/Observable';
 import { Observer } from 'rxjs/Observer';
 import { FirebaseApp } from '../tokens';
-import { isPresent, ZoneScheduler } from '../utils';
+import { ZoneScheduler } from '../utils';
 import {
   authDataToAuthState,
   AuthBackend,

src/database/firebase_list_factory.ts

@@ -49,44 +49,44 @@ export function FirebaseListFactory (
       }
 
       // check equalTo
-      if (utils.isPresent(query.equalTo)) {
+      if (!utils.isNil(query.equalTo)) {
           queried = queried.equalTo(query.equalTo);
 
-        if (utils.isPresent(query.startAt) || query.endAt) {
+        if (!utils.isNil(query.startAt) || query.endAt) {
           throw new Error('Query Error: Cannot use startAt or endAt with equalTo.');
         }
 
         // apply limitTos
-        if (utils.isPresent(query.limitToFirst)) {
+        if (!utils.isNil(query.limitToFirst)) {
           queried = queried.limitToFirst(query.limitToFirst);
         }
 
-        if (utils.isPresent(query.limitToLast)) {
+        if (!utils.isNil(query.limitToLast)) {
           queried = queried.limitToLast(query.limitToLast);
         }
 
         return queried;
       }
 
       // check startAt
-      if (utils.isPresent(query.startAt)) {
+      if (!utils.isNil(query.startAt)) {
           queried = queried.startAt(query.startAt);
       }
 
-      if (utils.isPresent(query.endAt)) {
+      if (!utils.isNil(query.endAt)) {
           queried = queried.endAt(query.endAt);
       }
 
-      if (utils.isPresent(query.limitToFirst) && query.limitToLast) {
+      if (!utils.isNil(query.limitToFirst) && query.limitToLast) {
         throw new Error('Query Error: Cannot use limitToFirst with limitToLast.');
       }
 
       // apply limitTos
-      if (utils.isPresent(query.limitToFirst)) {
+      if (!utils.isNil(query.limitToFirst)) {
           queried = queried.limitToFirst(query.limitToFirst);
       }
 
-      if (utils.isPresent(query.limitToLast)) {
+      if (!utils.isNil(query.limitToLast)) {
           queried = queried.limitToLast(query.limitToLast);
       }
 

src/database/query_observable.ts

@@ -14,10 +14,10 @@ import {
   LimitToSelection,
   Primitive
 } from '../interfaces';
-
+import { isNil } from '../utils';
 
 export function observeQuery(query: Query): Observable<ScalarQuery> {
-  if (!isPresent(query)) {
+  if (isNil(query)) {
     return observableOf(null);
   }
 
@@ -34,7 +34,7 @@ export function observeQuery(query: Query): Observable<ScalarQuery> {
         : [OrderBySelection, Primitive, Primitive, Primitive, LimitToSelection]) => {
 
         let serializedOrder: any = {};
-        if (isPresent(orderBy) && isPresent(orderBy.value)) {
+        if (!isNil(orderBy) && !isNil(orderBy.value)) {
           switch (orderBy.key) {
             case OrderByOptions.Key:
               serializedOrder = { orderByKey: <boolean>orderBy.value };
@@ -51,7 +51,7 @@ export function observeQuery(query: Query): Observable<ScalarQuery> {
           }
         }
 
-        if (isPresent(limitTo) && isPresent(limitTo.value)) {
+        if (!isNil(limitTo) && !isNil(limitTo.value)) {
           switch (limitTo.key) {
             case LimitToOptions.First:
               serializedOrder.limitToFirst = limitTo.value;
@@ -63,15 +63,15 @@ export function observeQuery(query: Query): Observable<ScalarQuery> {
           }
         }
 
-        if (isPresent(startAt)) {
+        if (!isNil(startAt)) {
           serializedOrder.startAt = startAt;
         }
 
-        if (isPresent(endAt)) {
+        if (!isNil(endAt)) {
           serializedOrder.endAt = endAt;
         }
 
-        if (isPresent(equalTo)) {
+        if (!isNil(equalTo)) {
           serializedOrder.equalTo = equalTo;
         }
 
@@ -86,7 +86,7 @@ export function getOrderObservables(query: Query): Observable<OrderBySelection>
       return ({ key, option })
     })
     .filter(({key, option}: { key: string, option: OrderByOptions }) => {
-      return isPresent(query[key]);
+      return !isNil(query[key]);
     })
     .map(({key, option}) => mapToOrderBySelection(<any>query[key], option));
 
@@ -104,7 +104,7 @@ export function getOrderObservables(query: Query): Observable<OrderBySelection>
 export function getLimitToObservables(query: Query): Observable<LimitToSelection> | Observable<LimitToSelection | Observable<LimitToSelection>> {
   var observables = ['limitToFirst', 'limitToLast']
     .map((key: string, option: LimitToOptions) => ({ key, option }))
-    .filter(({key, option}: { key: string, option: LimitToOptions }) => isPresent(query[key]))
+    .filter(({key, option}: { key: string, option: LimitToOptions }) => !isNil(query[key]))
     .map(({key, option}) => mapToLimitToSelection(<any>query[key], option));
 
   if (observables.length === 1) {
@@ -191,8 +191,3 @@ function hasObservableProperties(query: Query): boolean {
   if (query.orderByKey instanceof Observable) return true;
   return false;
 }
-
-function isPresent(val: any): boolean {
-  return val !== undefined && val !== null;
-}
-

src/utils.ts

@@ -4,8 +4,8 @@ import { Scheduler } from 'rxjs/Scheduler';
 import { queue } from 'rxjs/scheduler/queue';
 import { AFUnwrappedDataSnapshot} from './interfaces';
 
-export function isPresent(obj: any): boolean {
-  return obj !== undefined && obj !== null;
+export function isNil(obj: any): boolean {
+  return obj === undefined || obj === null;
 }
 
 export function isString(value: any): boolean {
@@ -29,7 +29,7 @@ export function isFirebaseQuery(value: any): boolean {
 }
 
 export function isEmptyObject(obj: Object): boolean {
-  if (!isPresent(obj)) { return false; }
+  if (isNil(obj)) { return false; }
   return Object.keys(obj).length === 0 && JSON.stringify(obj) === JSON.stringify({});
 }
 
@@ -47,7 +47,7 @@ export interface CheckUrlRef {
  * unwrapMapFn(snapshot) => { name: 'David', $key: 'david', $exists: Function }
  */
 export function unwrapMapFn (snapshot:firebase.database.DataSnapshot): AFUnwrappedDataSnapshot {
-  var unwrapped = isPresent(snapshot.val()) ? snapshot.val() : { $value: null };
+  var unwrapped = !isNil(snapshot.val()) ? snapshot.val() : { $value: null };
   if ((/string|number|boolean/).test(typeof unwrapped)) {
     unwrapped = {
       $value: unwrapped

src/worker/auth/worker/auth.ts

@@ -22,7 +22,7 @@ import {
   OAuth2Credentials,
   OAuthCredentials
 } from '../../auth_backend';
-import {isPresent} from '../../../utils';
+import {isNil} from '../../../utils';
 import * as firebase from 'firebase';
 
 @Injectable()
@@ -48,7 +48,7 @@ export class WebWorkerFirebaseAuth extends AuthBackend {
   onAuth (onComplete: (authData: FirebaseAuthData) => void): void {
     this._fbApp.onAuth((authData) => {
       if (!this._gotAuth) return false;
-      if (isPresent(authData) && isPresent(this._authMetadata[authData.token])) {
+      if (!isNil(authData) && !isNil(this._authMetadata[authData.token])) {
         authData = this._authMetadata[authData.token];
       }
       onComplete(authData);