fix(indexes): Limit indexes to three for sanity

examples/index.html

@@ -23,18 +23,18 @@
 
 		var ref = firebase.database().ref();
 		var peopleRef = ref.child("people");
-		var queryRef = querybase.ref(peopleRef, ['name', 'age', 'location', 'weight']);
+		var queryRef = querybase.ref(peopleRef, ['name', 'age', 'location']);
 
 		btnSeed.addEventListener('click', function(e) {
 			peopleRef.remove();
-			addPerson('David_East', 27, 'SF', 125);
-			addPerson('Shannon', 28, 'SF', 115);
-			addPerson('Coco', 1, 'SF', 12);
-			addPerson('Cash', 3, 'SF', 32);
-			addPerson('George', 27, 'DEN', 150);
-			addPerson('Bob', '27', 'SF', 160);
-			addPerson('Molly', 6, 'SF', 55);
-			addPerson('Mambo', 4, 'DEN', 6);
+			addPerson('David_East', 27, 'SF');
+			addPerson('Shannon', 28, 'SF');
+			addPerson('Coco', 1, 'SF');
+			addPerson('Cash', 3, 'SF');
+			addPerson('George', 27, 'DEN');
+			addPerson('Bob', '27', 'SF');
+			addPerson('Molly', 6, 'SF');
+			addPerson('Mambo', 4, 'DEN');
 		});
 
 		function listen(ref) {
@@ -47,8 +47,7 @@
 			queryRef.push({
 				name: name,
 				age: age,
-				location: location,
-				weight: weight
+				location: location
 			});
 		}
 

src/querybase.ts

@@ -27,6 +27,11 @@ interface QuerybaseUtils {
   values(obj): any[];
   encodeBase64(data: string): string;
   arraysToObject(keys, values): Object;
+  lexicographicallySort(a: string, b: string): number;
+  getKeyIndexPositions(arr: string[]): Object;
+  createSortedObject(keys: string[], values: any[]);
+  sortObjectLexicographically(obj: Object): Object;
+  decodeBase64(encoded: string): string;
 }
 
 const _: QuerybaseUtils = {
@@ -141,6 +146,19 @@ const _: QuerybaseUtils = {
     }
   },
 
+  /**
+   * Universal base64 decode method
+   * @param {string} data
+   * @return {string}
+   */  
+  decodeBase64(encoded: string): string {
+    if (this.isCommonJS()) {
+      return new Buffer(encoded, 'base64').toString('ascii');
+    } else {
+      return window.atob(encoded); 
+    }
+  },  
+
   /**
    * Creates an object from a keys array and a values array.
    * @param {any[]} keys
@@ -160,7 +178,73 @@ const _: QuerybaseUtils = {
       count++;
     });
     return indexHash;
+  },
+
+  /**
+   * A function for lexicographically comparing keys. Used for 
+   * array sort methods.
+   * @param {string} a
+   * @param {string} b
+   * @return {number}
+   */  
+  lexicographicallySort(a: string, b: string): number {
+    return a.localeCompare(b);
+  },
+
+  /**
+   * Creates an object with the key name and position in an array
+   * @param {string[]} arr
+   * @return {Object}
+   * @example
+   *  const keys = ['name', 'age', 'location'];
+   *  const indexKeys = _.getKeyIndexPositions(keys);
+   *    => { name: 0, age: 1, location: 2 }
+   */    
+  getKeyIndexPositions(arr: string[]): Object {
+    const indexOfKeys = {};
+    arr.forEach((key, index) => indexOfKeys[key] = index);
+    return indexOfKeys;
+  },
+
+  /**
+   * Creates an object whose keys are lexicographically sorted
+   * @param {string[]} keys
+   * @param {any[]} values
+   * @return {Object}
+   * @example
+   *  const keys = ['name', 'age', 'location'];
+   *  const values = ['David', '28', 'SF'];
+   *  const sortedObj = _.createSortedObject(keys, values);
+   *    => { age: '28', location: 'SF', name: 'David' }
+   */      
+  createSortedObject(keys: string[], values: any[]) {
+    const sortedRecord = {};
+    const indexOfKeys = this.getKeyIndexPositions(keys);
+    const sortedKeys = keys.sort(this.lexicographicallySort);
+
+    sortedKeys.forEach((key) => {
+      let index = indexOfKeys[key];
+      sortedRecord[key] = values[index];
+    });
+
+    return sortedRecord;
+  },
+
+  /**
+   * Creates an object whose keys are lexicographically sorted
+   * @param {obj} Object
+   * @return {Object}
+   * @example
+   *  const record = { name: 'David', age: '28', location: 'SF' };
+   *  const sortedObj = _.sortObjectLexicographically(record);
+   *    => { age: '28', location: 'SF', name: 'David' }
+   */  
+  sortObjectLexicographically(obj: Object): Object {
+    const keys = this.keys(obj);
+    const values = this.values(obj);
+    return this.createSortedObject(keys, values);
   }
+
 }
 
 /**
@@ -171,8 +255,8 @@ const _: QuerybaseUtils = {
  * 
  * @example
  *  // Querybase for multiple equivalency
- *  const firebaseRef = new Firebase('<my-app>/people');
- *  const querybaseRef = new Querybase(firebaseRef, ['name', 'age', 'location']);
+ *  const firebaseRef = firebase.database.ref().child('people');
+ *  const querybaseRef = querybase.ref(firebaseRef, ['name', 'age', 'location']);
  *  
  *  // Automatically handles composite keys
  *  querybaseRef.push({ 
@@ -198,6 +282,7 @@ const _: QuerybaseUtils = {
  *  querybaseRef.where('age').between(20, 30);
  */
 class Querybase {
+  INDEX_LENGTH = 3;
 
   // read only properties
 
@@ -206,7 +291,7 @@ class Querybase {
   // Returns a read-only set of indexes
   indexOn: () => string[];
   // the key of the Database ref
-  getKey: () => string;
+  key: string;
   // the set of indexOn keys base64 encoded
   private encodedKeys: () => string[];
 
@@ -219,36 +304,48 @@ class Querybase {
     // Check for constructor params and throw if not provided
     this._assertFirebaseRef(ref);
     this._assertIndexes(indexOn);
+    this._assertIndexLength(indexOn);
 
     this.ref = () => ref;
-    this.indexOn = () => indexOn;
+    this.indexOn = () => indexOn.sort(_.lexicographicallySort);
     /* istanbul ignore next */
-    this.getKey = () => this.ref().getKey();
+    this.key = this.ref().key;
     this.encodedKeys = () => this.encodeKeys(this.indexOn());
   }
 
   /**
-   * Check for a Firebase reference. Throw an exception if not provided.
+   * Check for a Firebase Database reference. Throw an exception if not provided.
    * @parameter {Firebase}
    * @return {void}
    */  
-  private _assertFirebaseRef(ref) {
+  private _assertFirebaseRef(ref: Firebase) {
     if (ref === null || ref === undefined || !ref.on) {
-      throw new Error(`No Firebase Reference provided in the Querybase constructor.`);
+      throw new Error(`No Firebase Database Reference provided in the Querybase constructor.`);
     }
   }
 
   /**
-   * Check for indexes. Throw and exception if not provided.
+   * Check for indexes. Throw an exception if not provided.
    * @param {string[]} indexes
    * @return {void}
    */    
-  private _assertIndexes(indexes) {
+  private _assertIndexes(indexes: any[]) {
     if (indexes === null || indexes === undefined) {
       throw new Error(`No indexes provided in the Querybase constructor. Querybase uses the indexOn() getter to create the composite queries for the where() method.`);
     }
   }
 
+  /**
+   * Check for indexes length. Throw and exception if greater than the INDEX_LENGTH value.
+   * @param {string[]} indexes
+   * @return {void}
+   */   
+  private _assertIndexLength(indexes: any[]) {
+    if (indexes.length > this.INDEX_LENGTH) {
+      throw new Error(`Querybase supports only ${this.INDEX_LENGTH} indexes for multiple querying.`)
+    }
+  }
+
   /**
    * Save data to the realtime database with composite keys
    * @param {any} data
@@ -322,9 +419,13 @@ class Querybase {
    * @return {FirebaseRef}
    */
   private _createQueryPredicate(criteria): QueryPredicate {
+
+    // Sort provided object lexicographically to match keys in database
+    const sortedCriteria = _.sortObjectLexicographically(criteria);
+
     // retrieve the keys and values array
-    const keys = _.keys(criteria);
-    const values = _.values(criteria);
+    const keys = _.keys(sortedCriteria);
+    const values = _.values(sortedCriteria);
 
     // warn about the indexes for indexOn rules
     this._warnAboutIndexOnRule();
@@ -391,7 +492,7 @@ class Querybase {
     if (_.isString(criteria)) {
       return this._createChildOrderedQuery(criteria);
     }
-
+    
     // Create the query predicate to build the Firebase Query
     const queryPredicate = this._createQueryPredicate(criteria);
     return this._createEqualToQuery(queryPredicate);
@@ -400,7 +501,7 @@ class Querybase {
   /**
    * Creates a set of composite keys with composite data. Creates every
    * possible combination of keys with respecive combined values. Redudant 
-   * keys are not included ('name~~age' vs. 'agenname').
+   * keys are not included ('name~~age' vs. 'age~~name').
    * @param {any[]} indexes
    * @param {Object} data
    * @param {Object?} indexHash for recursive check
@@ -490,13 +591,14 @@ class Querybase {
 
   /**
    * Encode (base64) all keys and data to avoid collisions with the
-   * chosen Querybase delimiter key (_)
+   * chosen Querybase delimiter key (~~)
    * @param {Object} indexWithData
    * @return {Object}
    */
   indexify(data: Object) {
     const compositeIndex = this._createCompositeIndex(this.indexOn(), data);
-    return this._encodeCompositeIndex(compositeIndex);
+    const encodedIndexes = this._encodeCompositeIndex(compositeIndex);
+    return encodedIndexes;
   }
 
   /**

tests/unit/querybase-utils.spec.js

@@ -10,6 +10,42 @@ const expect = chai.expect;
 
 describe('QuerybaseUtils', () => {
 
+  const smallRecord = {
+    zed: 'a',
+    name: 'David',
+    time: '5:01'
+  };
+
+  const mediumRecord = {
+    zed: 'a',
+    zzzz: 'zzzz',
+    name: 'David',
+    time: '5:01',
+    alpha: 'a',
+    yogi: 'bear',
+    jon: 'jon'
+  };  
+
+  const smallRecordKeys = _.keys(smallRecord);
+  const smallRecordValues = _.values(smallRecord);
+  const mediumRecordKeys = _.keys(mediumRecord);
+  const mediumRecordValues = _.values(mediumRecord);
+
+  const sortedSmallRecord = {
+    name: 'David',
+    time: '5:01',
+    zed: 'a'
+  };
+
+  const sortedMediumRecord = {
+    'alpha': 'a',
+    'jon': 'jon',
+    'name': 'David',
+    'time': '5:01',
+    'yogi': 'bear',
+    'zed': 'a',
+    'zzzz': 'zzzz'
+  };  
 
   it('should exist', () => { expect(_).to.exist; })
 
@@ -96,4 +132,66 @@ describe('QuerybaseUtils', () => {
 
   });
 
+  describe('lexicographicallySort', () => {
+
+    it('should lexicographically sort', () => {
+      const sorted = smallRecordKeys.slice().sort(_.lexicographicallySort);
+      assert.deepEqual(['name', 'time', 'zed'], sorted);
+    });
+
+    it('should lexicographically sort', () => {
+      const sorted = mediumRecordKeys.slice().sort(_.lexicographicallySort);
+      const expectedOrder = [
+        'alpha',
+        'jon',
+        'name',
+        'time',
+        'yogi',
+        'zed',
+        'zzzz'
+       ];
+      assert.deepEqual(expectedOrder, sorted);
+    });    
+
+  });
+
+  describe('getKeyIndexPositions', () => {
+
+    it('should create an object with the index positions', () => {
+
+      const indexOfKeys = _.getKeyIndexPositions(smallRecordKeys);
+      assert.deepEqual({ 'zed': 0, 'name': 1, 'time': 2 }, indexOfKeys);   
+
+    });
+
+  });
+
+  describe('createSortedObject', () => {
+
+    it('should create a sorted object', () => {
+      const sortedRecord = _.createSortedObject(smallRecordKeys, smallRecordValues);
+      assert.deepEqual(_.keys(sortedRecord), _.keys(sortedSmallRecord)); 
+    })
+
+    it('should create a sorted object', () => {
+      const sortedRecord = _.createSortedObject(mediumRecordKeys, mediumRecordValues);
+      assert.deepEqual(_.keys(sortedMediumRecord), _.keys(sortedRecord)); 
+    })    
+
+  });
+
+  describe('sortObjectLexicographically', () => {
+
+    it('sort an object lexicographically', () => {
+      const sortedRecord = _.sortObjectLexicographically(smallRecord);
+      assert.deepEqual(_.keys(sortedSmallRecord), _.keys(sortedRecord));
+    });
+
+    it('sort an object lexicographically', () => {
+      const sortedRecord = _.sortObjectLexicographically(mediumRecord);
+      assert.deepEqual(_.keys(sortedMediumRecord), _.keys(sortedRecord));
+    });    
+
+  });
+
 });