re-write

README.md

@@ -1,6 +1,6 @@
-# fs-db
+# fsdown
 
-a silly **work in progress** to use the filesystem as a database.
+a silly **work in progress** to use the filesystem (e.g. `.csv`, `.ldjson` files) as a database.
 
 the purpose is for apps to have human editable and readable data that can be iterated on easily (vim macros over sql migrations) and shared more openly (GitHub repos over JSON APIs).
 
@@ -17,21 +17,19 @@ npm install --save fs-db
 ```
 var FsDb = require('fs-db')
 
-var fsDb = FsDb({
-  location: __dirname + '/data',
+var db = FsDb({
+  location: __dirname + '/things.csv',
+  codec: 'csv'
 })
 
-fsDb.createReadStream()
-  .pipe(process.stdout)
+db.readStream()
+  .on('data', console.log)
 ```
 
-#### FsDb(options)
+#### fsdown(options)
 
-possible `options` are:
+`options`:
 
-- `location`: root filesystem directory of the database
-- `codec`: codec to use (defaults to 'json'), see [codecs](./codecs)
-
-#### fsDb.createReadStream()
-
-returns a readable [pull stream](https://npmjs.org/package/pull-stream) of objects with [JSON Pointer](https://npmjs.org/package/json-pointer) `id`s based on the path.
+- `location` is the path to the database file.
+- `codec` is which codec to use (defaults to 'csv'). can be a name of an existing codec, a custom codec object (see [codecs](./codecs) for what is expected of a codec), or an array where the first item is one of the previous values and the second item is options to pass to the codec.
+- `keyAttribute` is a string identifier of the attribute used as keys (e.g. 'id').

codecs/csv.js

@@ -1,11 +1,4 @@
-var csv = require('comma-separated-values')
-
 module.exports = {
-  type: 'csv',
-  encode: function (obj) {
-    return csv.encode(obj, { header: true })
-  },
-  decode: function (str) {
-    return csv.parse(str, { header: true })
-  }
+  decode: require('csv-parser'),
+  encode: require('csv-formatter')
 }

codecs/index.js

@@ -1,5 +1,3 @@
 module.exports = {
-  json: require('./json'),
-  yml: require('./yml'),
   csv: require('./csv')
 }

index.js

@@ -1,34 +1,131 @@
-var pull = require('pull-stream')
 var debug = require('debug')('fs-db')
+var fs = require('fs')
+var defined = require('defined')
+var inherits = require('inherits')
+var assign = require('lodash.assign')
+var forEach = require('lodash.foreach')
+var through = require('through2')
+var uuid = require('node-uuid')
+var pumpify = require('pumpify')
+var prepend = require('prepend-stream')
 
 var codecs = require('./codecs')
 
 module.exports = FsDb
 
 function FsDb (options) {
-  if (!(this instanceof FsDb)) {
+  if (!(this instanceof FsDb))
     return new FsDb(options)
+
+  if (typeof options == 'string') {
+    options = { location: options }
+  } else {
+    options = defined(options, {})
   }
-  debug("constructor(", options, ")")
 
-  this.location = options.location || process.cwd()
-  this.fs = options.fs || require('fs')
+  if (options.location == null) {
+    throw new Error('fs-db: options.location is required.')
+  }
 
-  var codec = options.codec || 'json'
-  this.codec = (typeof codec === 'string') ?
-    codecs[codec] : codec
+  this.location = options.location
+  this.codec = getCodec(options.codec)
+  this.keyAttribute = defined(options.keyAttribute, 'key')
 }
 
-FsDb.prototype = {
+assign(FsDb.prototype, {
   createReadStream: createReadStream,
+  createWriteStream: createWriteStream
+})
+
+function getCodec (codec) {
+  var codecOptions
+  if (Array.isArray(codec)) {
+    codecOptions = codec[1]
+    codec = codec[0]
+  } else {
+    codecOptions = {}
+  }
+
+  if (typeof codec === 'string') {
+    codec = codecs[codec]
+  } else if (!isCodec(codec)) {
+    codec = codecs.csv
+  }
+
+  return {
+    encode: codec.encode.bind(codec, codecOptions),
+    decode: codec.decode.bind(codec, codecOptions)
+  }
 }
 
-function createReadStream () {
-  debug('createReadStream()')
-
-  return pull(
-    require('./lib/read-dir')(this),
-    require('./lib/read-file')(this),
-    require('./lib/parse')(this)
+function isCodec (codec) {
+  return (
+    codec != null &&
+    typeof codec.encode === 'function' &&
+    typeof codec.decode === 'function'
   )
 }
+
+function createReadStream (options) {
+  debug('createReadStream(', options, ')')
+
+  var keyAttribute = this.keyAttribute
+
+  return pumpify.obj([
+    // read from file
+    fs.createReadStream(this.location),
+    // parse data into objects
+    this.codec.decode(),
+    through.obj(function (row, enc, cb) {
+      // get key
+      var key = row[keyAttribute]
+
+      // if no key, default to UUID
+      if (key == null) {
+        key = uuid()
+      }
+
+      cb(null, { key: key, value: row })
+    })
+  ])
+}
+
+function createWriteStream (options) {
+  debug('createWriteStream(', options, ')')
+
+  var table = {}
+
+  return pumpify.obj([
+    // parse values as json
+    // add current data to beginning of
+    // the data that is to be written
+    prepend.obj(
+      this.createReadStream(options)
+    ),
+    // construct in-memory table of data
+    through.obj(
+      function transform (row, enc, cb) {
+        debug("transform row", row)
+        // perform operation to table
+        if (row.type === 'del') {
+          delete table[row.key]
+        } else {
+          table[row.key] = row.value
+        }
+        cb()
+      },
+      function flush (cb) {
+        // output contents of table
+        debug("flush table", table)
+        forEach(table, function (value, key) {
+          this.push(value)
+        }, this)
+        cb()
+      }
+    ),
+    // format data to string
+    this.codec.encode(),
+    // write to file
+    fs.createWriteStream(this.location)
+  ])
+}