Drop support of key types other than string and Buffer (#191)

Author: vweevers

README.md

@@ -40,31 +40,32 @@ Your data is discarded when the process ends or you release a reference to the s
 
 ## Data types
 
-Unlike [`leveldown`], `memdown` does not stringify keys or values. This means that in addition to Buffers, you can store any JS type without the need for [`encoding-down`]. For keys for example, you could use Buffers or strings, which sort lexicographically, or numbers, even Dates, which sort naturally. The only exceptions are `null` and `undefined`. Keys and values of that type are rejected.
+Keys can be strings or Buffers. Any other key type will be irreversibly stringified. Unlike [`leveldown`] though, `memdown` does not stringify values. This means that in addition to Buffers, you can store any JS value without the need for [`encoding-down`]. The only exceptions are `null` and `undefined`. Keys and values of that type are rejected.
 
 ```js
 const db = levelup(memdown())
 
-db.put(12, true, (err) => {
+db.put('example', 123, (err) => {
   if (err) throw err
 
   db.createReadStream({
     keyAsBuffer: false,
     valueAsBuffer: false
   }).on('data', (entry) => {
-    console.log(typeof entry.key) // 'number'
-    console.log(typeof entry.value) // 'boolean'
+    console.log(typeof entry.key) // 'string'
+    console.log(typeof entry.value) // 'number'
   })
 })
 ```
 
-If you desire normalization for keys and values (e.g. to stringify numbers), wrap `memdown` with [`encoding-down`]. Alternatively install [`level-mem`] which conveniently bundles [`levelup`], `memdown` and [`encoding-down`]. Such an approach is also recommended if you want to achieve universal (isomorphic) behavior. For example, you could have [`leveldown`] in a backend and `memdown` in the frontend.
+If you desire normalization for values (e.g. to stringify numbers), wrap `memdown` with [`encoding-down`]. Alternatively install [`level-mem`] which conveniently bundles [`levelup`], `memdown` and [`encoding-down`]. Such an approach is also recommended if you want to achieve universal (isomorphic) behavior. For example, you could have [`leveldown`] in a backend and `memdown` in the frontend.
 
 ```js
 const encode = require('encoding-down')
 const db = levelup(encode(memdown()))
 
-db.put(12, true, (err) => {
+// The default value encoding is utf8, which stringifies input.
+db.put('example', 123, (err) => {
   if (err) throw err
 
   db.createReadStream({

UPGRADING.md

@@ -2,6 +2,10 @@
 
 This document describes breaking changes and how to upgrade. For a complete list of changes including minor and patch releases, please refer to the [`CHANGELOG`][changelog].
 
+## v5 (unreleased)
+
+Support of keys other than strings and Buffers has been dropped. Internally `memdown` now stores keys as Buffers which solves a number of compatibility issues ([#186](https://github.com/Level/memdown/issues/186)). If you pass in a key that isn't a string or Buffer, it will be irreversibly stringified.
+
 ## v4
 
 This is an upgrade to `abstract-leveldown@6` which solves long-standing issues around serialization and type support.

memdown.js

@@ -10,6 +10,7 @@ var Buffer = require('safe-buffer').Buffer
 var setImmediate = require('./immediate')
 var NONE = {}
 
+// TODO (perf): replace ltgt.compare with a simpler, buffer-only comparator
 function gt (value) {
   return ltgt.compare(value, this._upperBound) > 0
 }
@@ -97,8 +98,8 @@ MemIterator.prototype._next = function (callback) {
 
   if (!this._test(key)) return setImmediate(callback)
 
-  if (this.keyAsBuffer && !Buffer.isBuffer(key)) {
-    key = Buffer.from(String(key))
+  if (!this.keyAsBuffer) {
+    key = key.toString()
   }
 
   if (this.valueAsBuffer && !Buffer.isBuffer(value)) {
@@ -167,7 +168,7 @@ MemDOWN.prototype._open = function (options, callback) {
 }
 
 MemDOWN.prototype._serializeKey = function (key) {
-  return key
+  return Buffer.isBuffer(key) ? key : Buffer.from(String(key))
 }
 
 MemDOWN.prototype._serializeValue = function (value) {

test.js

@@ -364,46 +364,89 @@ test('put multiple times', function (t) {
   })
 })
 
-test('number keys', function (t) {
+test('put key as string, get as buffer and vice versa', function (t) {
+  t.plan(7)
+
+  var db = testCommon.factory()
+
+  db.open(function (err) {
+    t.ifError(err, 'no error from open')
+
+    db.put('a', 'a', function (err) {
+      t.ifError(err, 'no put error')
+
+      db.get(Buffer.from('a'), { asBuffer: false }, function (err, value) {
+        t.ifError(err, 'no get error')
+        t.is(value, 'a', 'got value')
+      })
+    })
+
+    db.put(Buffer.from('b'), 'b', function (err) {
+      t.ifError(err, 'no put error')
+
+      db.get('b', { asBuffer: false }, function (err, value) {
+        t.ifError(err, 'no get error')
+        t.is(value, 'b', 'got value')
+      })
+    })
+  })
+})
+
+test('put key as string, iterate as buffer', function (t) {
   t.plan(4)
 
   var db = testCommon.factory()
-  var numbers = [-Infinity, 0, 2, 12, +Infinity]
-  var buffers = numbers.map(stringBuffer)
 
-  db.open(noop)
-  db.batch(numbers.map(putKey), noop)
+  db.open(function (err) {
+    t.ifError(err, 'no error from open')
 
-  var iterator1 = db.iterator({ keyAsBuffer: false })
-  var iterator2 = db.iterator({ keyAsBuffer: true })
+    db.put('a', 'a', function (err) {
+      t.ifError(err, 'no put error')
 
-  concat(iterator1, function (err, entries) {
-    t.ifError(err, 'no iterator error')
-    t.same(entries.map(getKey), numbers, 'sorts naturally')
+      concat(db.iterator({ keyAsBuffer: true, valueAsBuffer: false }), function (err, entries) {
+        t.ifError(err, 'no concat error')
+        t.same(entries, [{ key: Buffer.from('a'), value: 'a' }])
+      })
+    })
   })
+})
 
-  concat(iterator2, function (err, entries) {
-    t.ifError(err, 'no iterator error')
-    t.same(entries.map(getKey), buffers, 'buffer input is stringified')
+test('put key as buffer, iterate as string', function (t) {
+  t.plan(4)
+
+  var db = testCommon.factory()
+
+  db.open(function (err) {
+    t.ifError(err, 'no error from open')
+
+    db.put(Buffer.from('a'), 'a', function (err) {
+      t.ifError(err, 'no put error')
+
+      concat(db.iterator({ keyAsBuffer: false, valueAsBuffer: false }), function (err, entries) {
+        t.ifError(err, 'no concat error')
+        t.same(entries, [{ key: 'a', value: 'a' }])
+      })
+    })
   })
 })
 
-test('date keys', function (t) {
+test('number keys', function (t) {
   t.plan(4)
 
   var db = testCommon.factory()
-  var dates = [new Date(0), new Date(1)]
-  var buffers = dates.map(stringBuffer)
+  var numbers = [-Infinity, 0, 12, 2, +Infinity]
+  var strings = numbers.map(String)
+  var buffers = numbers.map(stringBuffer)
 
   db.open(noop)
-  db.batch(dates.map(putKey), noop)
+  db.batch(numbers.map(putKey), noop)
 
-  var iterator = db.iterator({ keyAsBuffer: false })
+  var iterator1 = db.iterator({ keyAsBuffer: false })
   var iterator2 = db.iterator({ keyAsBuffer: true })
 
-  concat(iterator, function (err, entries) {
+  concat(iterator1, function (err, entries) {
     t.ifError(err, 'no iterator error')
-    t.same(entries.map(getKey), dates, 'sorts naturally')
+    t.same(entries.map(getKey), strings, 'sorts lexicographically')
   })
 
   concat(iterator2, function (err, entries) {