[firestore][js] implement Blob support

lib/modules/firestore/Blob.js

@@ -1,32 +1,40 @@
 import Base64 from './utils/Base64';
 
-type BlobFormat = 'string' | 'array';
-
 export default class Blob {
-  _data: Uint8Array | string;
-  _type: BlobFormat;
+  _binaryString: string;
 
-  constructor(data, type: BlobFormat) {
-    this._data = data;
-    this._type = type;
+  constructor(binaryString) {
+    this._binaryString = binaryString;
   }
 
   /**
    * Creates a new Blob from the given Base64 string
+   *
    * @url https://firebase.google.com/docs/reference/js/firebase.firestore.Blob#.fromBase64String
    * @param base64 string
    */
   static fromBase64String(base64: string): Blob {
-    return new Blob(base64, 'string');
+    return new Blob(Base64.atob(base64));
   }
 
   /**
    * Creates a new Blob from the given Uint8Array.
+   *
    * @url https://firebase.google.com/docs/reference/js/firebase.firestore.Blob#.fromUint8Array
    * @param array Array
    */
   static fromUint8Array(array: Uint8Array): Blob {
-    return new Blob(array, 'array');
+    if (!(array instanceof Uint8Array)) {
+      throw new Error(
+        'firestore.Blob.fromUint8Array expects an instance of Uint8Array'
+      );
+    }
+
+    return new Blob(
+      Array.prototype.map
+        .call(array, (char: number) => String.fromCharCode(char))
+        .join('')
+    );
   }
 
   /**
@@ -36,45 +44,42 @@ export default class Blob {
    * @returns boolean 'true' if this Blob is equal to the provided one.
    */
   isEqual(blob: Blob): boolean {
-    let thisBlobBase64 = '';
-    if (this._type === 'string') thisBlobBase64 = this._data;
-    else thisBlobBase64 = this.toBase64();
+    if (!(blob instanceof Blob)) {
+      throw new Error('firestore.Blob.isEqual expects an instance of Blob');
+    }
 
-    let thatBlobBase64 = '';
-    if (blob._type === 'string') thatBlobBase64 = blob._data;
-    else thatBlobBase64 = blob.toBase64();
-
-    return thisBlobBase64 === thatBlobBase64;
+    return this._binaryString === blob._binaryString;
   }
 
   /**
    * Returns the bytes of a Blob as a Base64-encoded string.
+   *
    * @url https://firebase.google.com/docs/reference/js/firebase.firestore.Blob#toBase64
    * @returns string The Base64-encoded string created from the Blob object.
    */
   toBase64(): string {
-    if (this._type === 'string') return this._data;
-
-    let binary = '';
-    const len = this._data.byteLength;
-    for (let i = 0; i < len; i++) {
-      binary += String.fromCharCode(this._data[i]);
-    }
-
-    return Base64.btoa(binary);
+    return Base64.btoa(this._binaryString);
   }
 
   /**
    * Returns the bytes of a Blob in a new Uint8Array.
+   *
    * @url https://firebase.google.com/docs/reference/js/firebase.firestore.Blob#toUint8Array
    * @returns non-null Uint8Array The Uint8Array created from the Blob object.
    */
   toUint8Array(): Uint8Array {
-    if (this._type === 'array') return this._data;
     return new Uint8Array(
-      Base64.atob(this._data)
-        .split('')
-        .map(c => c.charCodeAt(0))
+      this._binaryString.split('').map(c => c.charCodeAt(0))
     );
   }
+
+  /**
+   * Returns a string representation of this blob instance
+   *
+   * @returns {string}
+   * @memberof Blob
+   */
+  toString(): string {
+    return `firestore.Blob(base64: ${this.toBase64()})`;
+  }
 }

lib/modules/firestore/index.js

@@ -11,6 +11,7 @@ import DocumentReference from './DocumentReference';
 import FieldPath from './FieldPath';
 import FieldValue from './FieldValue';
 import GeoPoint from './GeoPoint';
+import Blob from './Blob';
 import Path from './Path';
 import WriteBatch from './WriteBatch';
 import TransactionHandler from './TransactionHandler';
@@ -258,6 +259,7 @@ export const statics = {
   FieldPath,
   FieldValue,
   GeoPoint,
+  Blob,
   enableLogging(enabled: boolean): void {
     // DEPRECATED: Remove method in v4.1.0
     console.warn(

lib/modules/firestore/types.js

@@ -42,6 +42,7 @@ export type NativeTypeMap = {
     | 'array'
     | 'boolean'
     | 'date'
+    | 'blob'
     | 'documentid'
     | 'fieldvalue'
     | 'geopoint'

lib/modules/firestore/utils/Base64.js

@@ -24,7 +24,7 @@ export default {
 
       if (charCode > 0xff) {
         throw new Error(
-          "'btoa' failed: The string to be encoded contains characters outside of the Latin1 range."
+          "'firestore.utils.btoa' failed: The string to be encoded contains characters outside of the Latin1 range."
         );
       }
 
@@ -48,7 +48,7 @@ export default {
 
     if (str.length % 4 === 1) {
       throw new Error(
-        "'atob' failed: The string to be decoded is not correctly encoded."
+        "'firestore.utils.atob' failed: The string to be decoded is not correctly encoded."
       );
     }
 

lib/modules/firestore/utils/serialize.js

@@ -3,6 +3,7 @@
  */
 
 import DocumentReference from '../DocumentReference';
+import Blob from '../Blob';
 import { DOCUMENT_ID } from '../FieldPath';
 import {
   DELETE_FIELD_VALUE,
@@ -98,6 +99,11 @@ export const buildTypeMap = (value: any): NativeTypeMap | null => {
         type: 'date',
         value: value.getTime(),
       };
+    } else if (value instanceof Blob) {
+      return {
+        type: 'blob',
+        value: value.toBase64(),
+      };
     }
     return {
       type: 'object',
@@ -156,6 +162,8 @@ const parseTypeMap = (firestore: Firestore, typeMap: NativeTypeMap): any => {
     return new GeoPoint(value.latitude, value.longitude);
   } else if (type === 'date') {
     return new Date(value);
+  } else if (type === 'blob') {
+    return Blob.fromBase64String(value);
   }
   console.warn(`Unknown data type received ${type}`);
   return value;