Added support for multi-attribute values

Author: squidfunk

package.json

@@ -34,14 +34,12 @@
     "watch": "make watch"
   },
   "dependencies": {
-    "flat": "^4.1.0",
     "lodash": "^4.17.10",
     "squel": "^5.12.2"
   },
   "devDependencies": {
     "@types/aws-lambda": "^8.10.8",
     "@types/chance": "^1.0.0",
-    "@types/flat": "0.0.28",
     "@types/jasmine": "^2.8.6",
     "@types/lodash": "^4.14.113",
     "@types/node": "^9.6.2",

src/isotopes/client/index.ts

@@ -21,7 +21,7 @@
  */
 
 import { SimpleDB } from "aws-sdk"
-import { toPairs } from "lodash"
+import { castArray, toPairs } from "lodash"
 
 import { IsotopeDictionary } from "../format"
 
@@ -63,6 +63,51 @@ const defaultOptions: IsotopeClientOptions = {
   consistent: false
 }
 
+/* ----------------------------------------------------------------------------
+ * Functions
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Map a dictionary to a list of SimpleDB attributes
+ *
+ * @param attrs - Attributes
+ *
+ * @return SimpleDB attributes
+ */
+export function mapDictionaryToAttributes(
+  attrs: IsotopeDictionary
+): SimpleDB.ReplaceableAttribute[] {
+  return toPairs(attrs)
+    .reduce<SimpleDB.ReplaceableAttribute[]>((list, [key, value]) => [
+      ...list,
+      ...castArray(value).map(entry => ({
+        Name: key,
+        Value: entry,
+        Replace: true
+      }))
+    ], [])
+}
+
+/**
+ * Map a list of SimpleDB attributes to a dictionary
+ *
+ * @param attrs - Attributes
+ *
+ * @return Dictionary
+ */
+export function mapAttributesToDictionary(
+  attrs: SimpleDB.Attribute[]
+): IsotopeDictionary {
+  return attrs
+    .reduce<IsotopeDictionary>((dict, { Name, Value }) => ({
+      ...dict,
+      ...(Name.match(/\[\]$/)
+        ? { [Name]: [ ...(dict[Name] || []), Value ] }
+        : { [Name]: Value }
+      )
+    }), {})
+}
+
 /* ----------------------------------------------------------------------------
  * Class
  * ------------------------------------------------------------------------- */
@@ -115,10 +160,7 @@ export class IsotopeClient {
     /* Map identifier and attributes */
     return {
       id,
-      attrs: Attributes
-        .reduce<IsotopeDictionary>((attrs, { Name, Value }) => ({
-          ...attrs, [Name]: Value
-        }), {})
+      attrs: mapAttributesToDictionary(Attributes)
     }
   }
 
@@ -136,12 +178,7 @@ export class IsotopeClient {
     await this.simpledb.putAttributes({
       DomainName: this.domain,
       ItemName: id,
-      Attributes: toPairs(attrs)
-        .map<SimpleDB.Attribute>(([key, value]) => ({
-          Name: key,
-          Value: value,
-          Replace: true
-        }))
+      Attributes: mapDictionaryToAttributes(attrs)
     }).promise()
   }
 
@@ -193,10 +230,7 @@ export class IsotopeClient {
     return {
       items: Items.map<IsotopeClientItem>(({ Name: id, Attributes }) => ({
         id,
-        attrs: Attributes
-          .reduce<IsotopeDictionary>((attrs, { Name, Value }) => ({
-            ...attrs, [Name]: Value
-          }), {})
+        attrs: mapAttributesToDictionary(Attributes)
       })),
       next: NextToken
     }

src/isotopes/format/encoding/index.ts

@@ -0,0 +1,113 @@
+/*
+ * Copyright (c) 2018 Martin Donath <[email protected]>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+/* ----------------------------------------------------------------------------
+ * Types
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Isotope value
+ */
+export type IsotopeValue = string | number | boolean | object
+
+/* ------------------------------------------------------------------------- */
+
+/**
+ * Isotope format encoding for values
+ */
+export type IsotopeFormatEncoding =
+  | "json"                             /* Default JSON encoding */
+  | "text"                             /* Strings are encoded as literals */
+
+/* ----------------------------------------------------------------------------
+ * Functions
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Encode a value using the given encoding
+ *
+ * By default every field is formatted as JSON in order to ensure type
+ * information not to be lost. However, this means that strings are actually
+ * double-quoted which may not be desirable if the SimpleDB domain is also used
+ * by other parts of your system as it cripples the querying experience.
+ *
+ * This library provides the ability to use an alternate encoding and store
+ * strings as literals so they are written without quotes. When decoding the
+ * data, we intercept JSON.parse assuming that we encountered a literal string
+ * if it fails to decode. However, this imposes the following limitations:
+ *
+ * 1. Numbers that are encoded as strings (e.g. house numbers, because they can
+ *    exhibit values as "2A" etc.) are interpreted as numbers when decoded with
+ *    JSON.parse. Countermeasure: ensure that numbers are typed as numbers, or
+ *    string fields contain at least one non-number character.
+ *
+ * 2. If strings accidentally contain valid JSON, e.g. "{}", the value is parsed
+ *    as JSON and the field gets assigned that precise value. This also breaks
+ *    type safety. Countermeasure: ensure that your strings are never valid JSON
+ *    by prepending some character that makes JSON.parse fail.
+ *
+ * As enforcing as those restrictions may seem to be, it is often true that
+ * the properties and characteristics of the data are known a-priori and those
+ * special cases can be ruled out with great certainty. This also means that
+ * querying the data from other parts of your system gets easier as string
+ * values don't need to be enclosed into quotes (and don't start thinking about
+ * LIKE queries) which is far more user-friendly.
+ *
+ * @internal
+ *
+ * @param value - Value to encode
+ * @param encoding - Encoding
+ *
+ * @return Encoded value
+ */
+export function encode(
+  value: IsotopeValue, encoding: IsotopeFormatEncoding
+): string {
+  return encoding === "json" || typeof value !== "string"
+    ? JSON.stringify(value)
+    : value
+}
+
+/**
+ * Decode a value using the given encoding
+ *
+ * See the function documentation on flatten() for a detailed explanation on
+ * how error handling is implemented and why.
+ *
+ * @internal
+ *
+ * @param value - Value to decode
+ * @param encoding - Encoding
+ *
+ * @return Decoded value
+ */
+export function decode(
+  value: string, encoding: IsotopeFormatEncoding
+): IsotopeValue {
+  try {
+    return JSON.parse(value)
+  } catch (err) {
+    if (encoding === "text")
+      return value
+    throw err
+  }
+}