decouple from level-sublevel

README.md

@@ -20,11 +20,11 @@ var db = sub(level(__dirname + '/db', {
 var posts = db.sublevel('posts');
 
 // add a title index
-posts.byTitle = Secondary(posts, 'title');
+posts.byTitle = Secondary(posts, db.sublevel('title'), 'title');
 
 // add a length index
 // append the post.id for unique indexes with possibly overlapping values
-posts.byLength = Secondary(posts, 'length', function(post){
+posts.byLength = Secondary(posts, db.sublevel('length'), function(post){
   return post.body.length + '!' + post.id;
 });
 
@@ -69,12 +69,33 @@ posts.put('1337', {
 });
 ```
 
+Same arrangement as above, but using a separate index level and [subleveldown](https://github.com/mafintosh/subleveldown) instead of [level-sublevel](https://github.com/dominictarr/level-sublevel).
+
+```js
+var level = require('level');
+var Secondary = require('level-secondary');
+var sub = require('subleveldown');
+
+var db = level(__dirname + '/db');
+var idb = level(__dirname + '/idb');
+
+var posts = sub(db, 'posts', { valueEncoding: 'json' });
+
+// add a title index
+posts.byTitle = Secondary(posts, sub(idb, 'title', { valueEncoding: 'json' }), 'title');
+
+// add a length index
+// append the post.id for unique indexes with possibly overlapping values
+posts.byLength = Secondary(posts, sub(idb, 'length', { valueEncoding: 'json' }), function(post){
+  return post.body.length + '!' + post.id;
+});
+```
+
 ## API
 
-### Secondary(db, name[, reduce])
+### Secondary(db, idb[, reduce])
 
-Return a secondary index that either indexes property `name` or uses a custom
-`reduce` function to map values to indexes.
+Takes any level as `db` and any level as `idb` to use as a secondary index that either indexes a property name if `reduce` is a string or uses a custom `reduce` function to map values to indexes.  The level that gets passed as `db` gets mutated by [`dominictarr/level-hooks`](https://github.com/dominictarr/level-hooks) in order to capture db events.  Secondary returns a wrapped `idb` level that helps prune old index values.
 
 ### Secondary#get(key, opts[, cb])
 
@@ -90,6 +111,48 @@ A [level manifest](https://github.com/dominictarr/level-manifest) that you can p
 
 ## Breaking changes
 
+### 2.0.0
+
+You are now in charge of creating isolated levels for indexes yourself now.  This allows for greater flexibility on key and value encodings, and lets you separate out storage locations, as well as use other `sublevel` solutions.
+
+What used to be
+
+```js
+var level = require('level');
+var Secondary = require('level-secondary');
+var sub = require('level-sublevel');
+
+var db = sub(level(__dirname + '/db', {
+  valueEncoding: 'json'
+}));
+
+var posts = db.sublevel('posts');
+
+posts.byTitle = Secondary(posts, 'title');
+posts.byLength = Secondary(posts, 'length', function(post){
+  return post.body.length + '!' + post.id;
+});
+```
+
+is now
+
+```js
+var level = require('level');
+var Secondary = require('level-secondary');
+var sub = require('level-sublevel');
+
+var db = sub(level(__dirname + '/db', {
+  valueEncoding: 'json'
+}));
+
+var posts = db.sublevel('posts');
+
+posts.byTitle = Secondary(posts, db.sublevel('title'), 'title');
+posts.byLength = Secondary(posts, db.sublevel('length'), function(post){
+  return post.body.length + '!' + post.id;
+});
+```
+
 ### 1.0.0
 
 What used to be

index.js

@@ -1,31 +1,39 @@
 var extend = require('xtend');
+var hooks = require('level-hooks');
 var Transform = require('stream').Transform
   || require('readable-stream').Transform;
 
 module.exports = Secondary;
 
-function Secondary(db, name, reduce) {
-  var sub = db.sublevel(name);
+function Secondary(db, idb, reduce) {
+  if (db.sublevel && !db.hooks) {
+    db.hooks = {}
+    db.hooks.pre = db.pre
+    db.hooks.post = db.post
+  }
+
+  if (!db.hooks) {
+    hooks(db)
+  }
 
-  if (!reduce) {
+  if (reduce && typeof reduce === 'string') {
+    var reducerString = reduce
     reduce = function(value) {
-      return value[name];
+      return value[reducerString]
     };
   }
 
-  db.pre(function(change, add) {
-    if (change.type != 'put') return;
+  if (typeof reduce !== 'function') {
+    throw new Error('Reduce argument must be a string or function')
+  }
 
-    add({
-      type: 'put',
-      key: reduce(change.value),
-      value: change.key,
-      prefix: sub
-    });
+  db.hooks.pre(function(change, add) {
+    if (change.type != 'put') return;
+    idb.put(reduce(change.value), change.key)
   });
 
   var secondary = {};
-  
+
   secondary.manifest = {
     methods: {
       get: { type: 'async' },
@@ -46,7 +54,7 @@ function Secondary(db, name, reduce) {
         opts = {};
       }
 
-      sub.get(key, function(err, value) {
+      idb.get(key, function(err, value) {
         if (err) return fn(err);
         db[type](value, opts, fn);
       });
@@ -69,15 +77,14 @@ function Secondary(db, name, reduce) {
 
     tr._transform = function(chunk, enc, done) {
       var key = chunk.value;
-
       if (opts.values === false) {
         done(null, key);
         return;
       }
 
       db.get(key, function(err, value) {
         if (err && err.type == 'NotFoundError') {
-          sub.del(key, done);
+          idb.del(key, done);
         } else if (err) {
           done(err);
         } else {
@@ -99,7 +106,7 @@ function Secondary(db, name, reduce) {
 
     var opts2 = extend({}, opts);
     opts2.keys = opts2.values = true;
-    sub.createReadStream(opts2).pipe(tr);
+    idb.createReadStream(opts2).pipe(tr);
 
     return tr;
   };

package.json

@@ -12,14 +12,16 @@
     "test": "tape test/*.js"
   },
   "dependencies": {
-    "xtend": "~4.0.1",
-    "readable-stream": "~2.2.0"
+    "level-hooks": "^4.5.0",
+    "readable-stream": "~2.2.0",
+    "xtend": "~4.0.1"
   },
   "devDependencies": {
-    "tape": "*",
     "level-sublevel": "~6.6.1",
     "memdb": "1.3.1",
-    "multilevel": "~7.3.0"
+    "multilevel": "~7.3.0",
+    "subleveldown": "^2.1.0",
+    "tape": "*"
   },
   "keywords": [
     "level",

test/del.js

@@ -6,9 +6,10 @@ var test = require('tape');
 test('del', function(t) {
   t.plan(5);
   var db = sub(level({ valueEncoding: 'json' }));
+  var idb = db.sublevel('title')
 
   var posts = db.sublevel('posts');
-  posts.byTitle = Secondary(posts, 'title');
+  posts.byTitle = Secondary(posts, idb, 'title');
 
   posts.put('1337', {
     title: 'a title',

test/get.js

@@ -4,12 +4,16 @@ var sub = require('level-sublevel');
 var test = require('tape');
 
 test('get', function(t) {
-  t.plan(3);
+  t.plan(5);
   var db = sub(level({ valueEncoding: 'json' }));
+  var index = {
+    title: db.sublevel('title'),
+    len: db.sublevel('length')
+  }
 
   var posts = db.sublevel('posts');
-  posts.byTitle = Secondary(posts, 'title');
-  posts.byLength = Secondary(posts, 'length', function(post){
+  posts.byTitle = Secondary(posts, index.title, 'title');
+  posts.byLength = Secondary(posts, index.len, function(post){
     return post.body.length;
   });
 
@@ -24,6 +28,10 @@ test('get', function(t) {
     posts.byTitle.get('a title', function(err, _post) {
       t.error(err);
       t.deepEqual(_post, post);
+      posts.byLength.get(post.body.length, function(err, _post) {
+        t.error(err)
+        t.deepEqual(_post, post)
+      })
     });
   });
 });

test/multilevel.js

@@ -6,9 +6,10 @@ var multilevel = require('multilevel');
 
 test('multilevel', function(t) {
 	t.plan(3);
-	
+
 	var db = sub(level({ valueEncoding: 'json' }));
-	var byTitle = Secondary(db, 'title');
+	var idb = db.sublevel('title')
+	var byTitle = Secondary(db, idb, 'title');
 	var server = multilevel.server(byTitle);
 	var client = multilevel.client(byTitle.manifest);
 

test/read-stream.js

@@ -6,10 +6,14 @@ var test = require('tape');
 test('read streams', function(t) {
   t.plan(4);
   var db = sub(level({ valueEncoding: 'json' }));
+  var index = {
+    title: db.sublevel('title'),
+    len: db.sublevel('length')
+  };
 
   var posts = db.sublevel('posts');
-  posts.byTitle = Secondary(posts, 'title');
-  posts.byLength = Secondary(posts, 'length', function(post){
+  posts.byTitle = Secondary(posts, index.title, 'title');
+  posts.byLength = Secondary(posts, index.len, function(post){
     return post.body.length;
   });
 
@@ -20,7 +24,6 @@ test('read streams', function(t) {
 
   posts.put('1337', post, function(err) {
     t.error(err);
-
     posts.byLength.createReadStream({
       start: 10,
       end: 20

test/subleveldown.js

@@ -0,0 +1,54 @@
+var level = require('memdb');
+var Secondary = require('..');
+var sub = require('subleveldown');
+var test = require('tape');
+
+test('subleveldown', function(t) {
+  t.plan(4);
+  var db = level();
+  var idb = level();
+
+  var index = {
+    title: sub(idb, 'title', { valueEncoding: 'json' }),
+    len: sub(idb, 'length', { valueEncoding: 'json' })
+  };
+
+  var posts = sub(db, 'posts', { valueEncoding: 'json' });
+  posts.byTitle = Secondary(posts, index.title, 'title');
+  posts.byLength = Secondary(posts, index.len, function(post){
+    return post.body.length;
+  });
+
+  var post = {
+    title: 'a title',
+    body: 'lorem ipsum'
+  };
+
+  posts.put('1337', post, function(err) {
+    t.error(err);
+    posts.byLength.createReadStream({
+      start: 10,
+      end: 20
+    }).on('data', function(data) {
+      t.deepEqual(data, {
+        key: '1337',
+        value: post
+      });
+    });
+
+    posts.byLength.createKeyStream({
+      start: 10,
+      end: 20
+    }).on('data', function(data) {
+      t.equal(data, '1337');
+    });
+
+    posts.byLength.createValueStream({
+      start: 10,
+      end: 20
+    }).on('data', function(data) {
+      t.deepEqual(data, post);
+    });
+  });
+});
+