From fb16f02a35658a262ee5c62be79cf018b0bc78d2 Mon Sep 17 00:00:00 2001
From: Torgny Bjers <torgny@xorcode.com>
Date: Wed, 9 Oct 2013 21:52:46 -0400
Subject: [PATCH] Added progressive enhancement to adapters Will warn when an
 adapter is instantiated if its driver is not installed.

---
 lib/adapters/level/index.js  | 13 ++++++++++++-
 lib/adapters/mongo/index.js  | 13 ++++++++++++-
 lib/adapters/sql/postgres.js | 13 ++++++++++++-
 package.json                 |  5 +----
 4 files changed, 37 insertions(+), 7 deletions(-)

diff --git a/lib/adapters/level/index.js b/lib/adapters/level/index.js
index 116a9eb0..cc9d6f51 100644
--- a/lib/adapters/level/index.js
+++ b/lib/adapters/level/index.js
@@ -6,7 +6,7 @@ var model = require('../../index')
   , datatypes = require('../../datatypes')
   , request = utils.request
   , BaseAdapter = require('../base_adapter').BaseAdapter
-  , level = require('level')
+  , level = undefined
   , _baseConfig
   , _data = {}
   , delimiter = '!';
@@ -15,6 +15,11 @@ _baseConfig = {
   db: '/data/level'
 };
 
+// Progressive adapter enhancement
+try {
+  level = require('level');
+} catch (err) {}
+
 var Adapter = function (options) {
   var opts = options || {}
     , config;
@@ -36,6 +41,12 @@ utils.mixin(Adapter.prototype, new (function () {
 
   this.init = function () {
     var config = this.config;
+    if (level === 'undefined') {
+      // Progressive enhancement failed, notify user
+      console.warn('The LevelDB driver is not installed.\nInstall it with `npm install level --save`');
+      console.trace();
+      process.exit(1);
+    }
     this.db = level(config.db, {keyEncoding: 'utf8', valueEncoding: 'json'});
   };
 
diff --git a/lib/adapters/mongo/index.js b/lib/adapters/mongo/index.js
index eec3a172..dd4d5f4c 100644
--- a/lib/adapters/mongo/index.js
+++ b/lib/adapters/mongo/index.js
@@ -1,6 +1,6 @@
 var model = require('../../index')
   , file = require('utilities').file
-  , driver = require('mongodb-wrapper')
+  , driver = undefined
   , utils = require('utilities')
   , operation = require('../../query/operation')
   , comparison = require('../../query/comparison')
@@ -12,6 +12,11 @@ var model = require('../../index')
   , _comparisonTypeMap
   , _collectionizeModelName;
 
+// Progressive adapter enhancement
+try {
+  driver = require('mongodb-wrapper');
+} catch (err) {}
+
 _baseConfig = {
   username: null
 , dbname: null
@@ -173,6 +178,12 @@ utils.mixin(Adapter.prototype, new (function () {
   this.init = function () {
     var config = this.config
       , args = [];
+    if (driver === undefined) {
+      // Progressive enhancement failed, notify user
+      console.warn('The MongoDB drivers are not installed.\nInstall them with `npm install mongodb mongodb-wrapper --save`');
+      console.trace();
+      process.exit(1);
+    }
     ['host', 'port', 'dbname', 'prefix', 'username',
         'password'].forEach(function (c) {
       args.push(config[c]);
diff --git a/lib/adapters/sql/postgres.js b/lib/adapters/sql/postgres.js
index 0399d7b2..9e1e1c40 100644
--- a/lib/adapters/sql/postgres.js
+++ b/lib/adapters/sql/postgres.js
@@ -1,5 +1,5 @@
 var file = require('utilities').file
-  , pg = require('pg')
+  , pg = undefined
   , generator = require('../../generators/sql')
   , utils = require('utilities')
   , model = require('../../index')
@@ -8,6 +8,11 @@ var file = require('utilities').file
   , Adapter
   , _baseConfig;
 
+// Progressive adapter enhancement
+try {
+  pg = require('pg');
+} catch (err) {}
+
 _baseConfig = {
   user: process.env.USER
 , database: process.env.USER
@@ -159,6 +164,12 @@ utils.mixin(Adapter.prototype, new (function () {
       };
 
   this.init = function () {
+    if (pg === undefined) {
+      // Progressive enhancement failed, notify user
+      console.warn('The PostgreSQL driver is not installed.\nInstall it with `npm install pg --save`');
+      console.trace();
+      process.exit(1);
+    }
     this.client = new pg.Client(this.config);
   };
 
diff --git a/package.json b/package.json
index 68592d14..e2d4f979 100644
--- a/package.json
+++ b/package.json
@@ -25,10 +25,7 @@
     "url": "git://github.com/mde/model.git"
   },
   "dependencies": {
-    "utilities": "0.0.x",
-    "mongodb-wrapper": "0.4.x",
-    "pg": "0.9.x",
-    "level": "0.17.x"
+    "utilities": "0.0.x"
   },
   "devDependencies": {
     "jake": "0.7.x"