Graceful fallback if the renderer process can't access the remote module

Right now this module will crash when being ran on a renderer process
that cannot access the `remote` module for determining a default data
path. After this commit, the module will gracefully require users to
call `.setDataPath()` if `remote.app` cannot be accessed.

See: #155
Signed-off-by: Juan Cruz Viotti <[email protected]>

README.md

@@ -30,40 +30,22 @@ You can require this module from either the **main** or **renderer** process (wi
 Running on Electron >10 renderer processes
 ------------------------------------------
 
-When loaded in renderer processes, this module will make use of
+When loaded in renderer processes, this module will try to make use of
 `electron.remote` in order to fetch the `userData` path.
 
 Electron 10 now [defaults `enableRemoteModule` to
 false](https://www.electronjs.org/docs/breaking-changes#default-changed-enableremotemodule-defaults-to-false),
-which means that `electron-json-storage` will not work on Electron 10 renderer
-processes unless you manually set `enableRemoteModule` to `true`:
+which means that `electron-json-storage` will be able to calculate a data path by default.
 
-```js
-const win = new BrowserWindow({
-  webPreferences: {
-    enableRemoteModule: true
-  }
-})
-```
-
-Alternatively, you can avoid using the `remote` module by:
-
-- Passing the `electron.app.getPath('userData')` value from the **main**
-  process to your **renderer** processes through IPC or a medium of your choice
-
-- Calling `storage.setDataPath()`, on the **renderer** process, with the user
-  data path obtained on the previous step before calling any other
-  `electron-json-storage` function.
-
-If you do this, the user data path will be cached by the renderer process,
-which will not need to go through the `remote` module to obtain it.
+The solution is to manually call `storage.setDataPath()` before reading or
+writing any values or setting `enableRemoteModule` to `true`.
 
 Documentation
 -------------
 
 
 * [storage](#module_storage)
-    * [.getDefaultDataPath()](#module_storage.getDefaultDataPath) ⇒ <code>String</code>
+    * [.getDefaultDataPath()](#module_storage.getDefaultDataPath) ⇒ <code>String</code> \| <code>Null</code>
     * [.setDataPath(directory)](#module_storage.setDataPath)
     * [.getDataPath()](#module_storage.getDataPath) ⇒ <code>String</code>
     * [.get(key, [options], callback)](#module_storage.get)
@@ -77,10 +59,15 @@ Documentation
 
 <a name="module_storage.getDefaultDataPath"></a>
 
-### storage.getDefaultDataPath() ⇒ <code>String</code>
+### storage.getDefaultDataPath() ⇒ <code>String</code> \| <code>Null</code>
+This function will return `null` when running in the
+renderer process without support for the `remote` IPC
+mechanism. You have to explicitly set a data path using
+`.setDataPath()` in these cases.
+
 **Kind**: static method of [<code>storage</code>](#module_storage)  
 **Summary**: Get the default data path  
-**Returns**: <code>String</code> - default data path  
+**Returns**: <code>String</code> \| <code>Null</code> - default data path  
 **Access**: public  
 **Example**  
 ```js
@@ -222,6 +209,7 @@ storage.getAll(function(error, data) {
 | [options] | <code>Object</code> | options |
 | [options.dataPath] | <code>String</code> | data path |
 | [options.validate] | <code>String</code> | validate writes by reading the data back |
+| [options.prettyPrinting] | <code>boolean</code> | adds line breaks and spacing to the written data |
 | callback | <code>function</code> | callback (error) |
 
 **Example**  

doc/README.hbs

@@ -30,33 +30,15 @@ You can require this module from either the **main** or **renderer** process (wi
 Running on Electron >10 renderer processes
 ------------------------------------------
 
-When loaded in renderer processes, this module will make use of
+When loaded in renderer processes, this module will try to make use of
 `electron.remote` in order to fetch the `userData` path.
 
 Electron 10 now [defaults `enableRemoteModule` to
 false](https://www.electronjs.org/docs/breaking-changes#default-changed-enableremotemodule-defaults-to-false),
-which means that `electron-json-storage` will not work on Electron 10 renderer
-processes unless you manually set `enableRemoteModule` to `true`:
-
-```js
-const win = new BrowserWindow({
-  webPreferences: {
-    enableRemoteModule: true
-  }
-})
-```
-
-Alternatively, you can avoid using the `remote` module by:
-
-- Passing the `electron.app.getPath('userData')` value from the **main**
-  process to your **renderer** processes through IPC or a medium of your choice
-
-- Calling `storage.setDataPath()`, on the **renderer** process, with the user
-  data path obtained on the previous step before calling any other
-  `electron-json-storage` function.
+which means that `electron-json-storage` will be able to calculate a data path by default.
 
-If you do this, the user data path will be cached by the renderer process,
-which will not need to go through the `remote` module to obtain it.
+The solution is to manually call `storage.setDataPath()` before reading or
+writing any values or setting `enableRemoteModule` to `true`.
 
 Documentation
 -------------

lib/storage.js

@@ -66,7 +66,13 @@ const readFile = function(fileName, callback, times) {
  * @function
  * @public
  *
- * @returns {String} default data path
+ * @description
+ * This function will return `null` when running in the
+ * renderer process without support for the `remote` IPC
+ * mechanism. You have to explicitly set a data path using
+ * `.setDataPath()` in these cases.
+ *
+ * @returns {(String|Null)} default data path
  *
  * @example
  * const defaultDataPath = storage.getDefaultDataPath()

lib/utils.js

@@ -27,7 +27,7 @@
 const _ = require('lodash');
 const path = require('path');
 const electron = require('electron');
-const app = electron.app || electron.remote.app;
+const app = electron.app || (electron.remote && electron.remote.app) || null;
 
 /**
  * @summary Get the default data path
@@ -40,6 +40,10 @@ const app = electron.app || electron.remote.app;
  * const defaultDataPath = utils.getDefaultDataPath()
  */
 exports.getDefaultDataPath = function() {
+  if (!app) {
+    return null;
+  }
+
   return path.join(app.getPath('userData'), 'storage');
 };
 
@@ -123,7 +127,12 @@ exports.getFileName = function(key, options) {
   const escapedFileName = encodeURIComponent(keyFileName)
     .replace(/\*/g, '-').replace(/%20/g, ' ');
 
-  return path.join(options.dataPath || exports.getDataPath(), escapedFileName);
+  const dataPath = options.dataPath || exports.getDataPath();
+  if (!dataPath) {
+    throw new Error('You must explicitly set a data path');
+  }
+
+  return path.join(dataPath, escapedFileName);
 };
 
 /**