Implement find and filter

README.md

@@ -17,20 +17,41 @@ npm install --save doubledb
 - [x]  replace
 - [x]  patch
 - [x]  remove
-- [ ]  find
+- [x]  find
+- [x]  filter
+- [ ]  query
 
 ## Usage
 ```javascript
-const createDoubled = require('doubledb')
-const doubled = doubled('./data')
+import createDoubledb from 'doubledb';
+const doubledb = createDoubledb('./data');
 
-doubled.insert({
+doubledb.insert({
   id: undefined, // defaults to uuid, must be unique
   firstName: 'Joe',
-  lastName: 'Bloggs'
-})
+  lastName: 'Bloggs',
+  stats: {
+    wins: 10,
+    loses: 5
+  },
+  skills: ['cooking', 'running']
+});
+
+doubledb.get(record.id);
+doubledb.find('firstName', 'Joe');
+doubledb.find('stats.wins', 10);
+doubledb.find('skills', 'cooking');
+doubledb.find('firstName', v => v.startsWith('J'));
+doubledb.filter('firstName', 'Joe');
+doubledb.filter('firstName', v => v.startsWith('J'));
+doubledb.replace(record.id, { firstName: 'Joe', lastName: 'Bloggs' });
+doubledb.patch(record.id, { firstName: 'Bob' });
+doubledb.remove(record.id);
+```
 
-const record = doubled.find({
+### Proposed Query
+```javascript
+const record = doubledb.query({
   location: 'London',
   category: 'b',
 
@@ -43,8 +64,4 @@ const record = doubled.find({
     }
   }
 })
-
-doubled.replace(record.id, { firstName: 'Joe', lastName: 'Bloggs' })
-doubled.patch(record.id, { firstName: 'Bob' })
-doubled.remove(record.id)
-```
+```

index.js

@@ -1,6 +1,6 @@
-const fs = require('fs').promises;
-const { Level } = require('level');
-const uuid = require('uuid').v4;
+import { promises as fs } from 'fs';
+import { Level } from 'level';
+import { v4 as uuid } from 'uuid';
 
 function notFoundToUndefined (error) {
   if (error.code === 'LEVEL_NOT_FOUND') {
@@ -10,18 +10,29 @@ function notFoundToUndefined (error) {
   throw error;
 }
 
+const isObject = thing => thing instanceof Object && !Array.isArray(thing);
+
 async function createDoubleDb (dataDirectory) {
   await fs.mkdir(dataDirectory, { recursive: true });
 
   const db = new Level(dataDirectory);
 
   async function addToIndexes (id, object, prefix = '') {
     const promises = Object.keys(object).map(key => {
-      if (typeof object[key] === 'object') {
-        return addToIndexes(id, object[key], prefix + '.' + key);
+      if (isObject(object[key])) {
+        addToIndexes(id, object[key], prefix + '.' + key);
+        return null;
+      }
+
+      if (Array.isArray(object[key])) {
+        for (const index in object[key]) {
+          db.put('indexes' + prefix + '.' + key + '.' + id + '=' + object[key][index], id);
+        }
+        return null;
       }
 
-      return db.put('indexes' + prefix + '.' + key + '.' + id + '=' + object[key], id);
+      db.put('indexes' + prefix + '.' + key + '.' + id + '=' + object[key], id);
+      return null;
     });
 
     return Promise.all(promises);
@@ -123,6 +134,46 @@ async function createDoubleDb (dataDirectory) {
     return JSON.parse(document);
   }
 
+  async function findOrFilter (type, key, valueOrFunction) {
+    const lookupType = valueOrFunction instanceof Function ? 'function' : 'value';
+
+    const promises = [];
+    for await (const [ckey, id] of db.iterator({
+      gt: `indexes.${key}.`,
+      lt: `indexes.${key}~`
+    })) {
+      const [, lvalue] = ckey.split('=');
+      if (lookupType === 'value' && lvalue == valueOrFunction) {
+        promises.push(read(id));
+        if (type === 'find') {
+          break;
+        }
+      }
+
+      if (lookupType === 'function' && valueOrFunction(lvalue)) {
+        promises.push(read(id));
+        if (type === 'find') {
+          break;
+        }
+      }
+    }
+
+    const results = await Promise.all(promises);
+    if (type === 'filter') {
+      return results;
+    } else {
+      return results[0];
+    }
+  }
+
+  async function find (key, valueOrFunction) {
+    return findOrFilter('find', key, valueOrFunction);
+  }
+
+  async function filter (key, valueOrFunction) {
+    return findOrFilter('filter', key, valueOrFunction);
+  }
+
   async function remove (id) {
     if (!id) {
       throw new Error('doubledb.remove: no id was supplied to replace function');
@@ -140,6 +191,8 @@ async function createDoubleDb (dataDirectory) {
 
   return {
     _level: db,
+    find,
+    filter,
     insert,
     replace,
     patch,
@@ -149,4 +202,4 @@ async function createDoubleDb (dataDirectory) {
   };
 }
 
-module.exports = createDoubleDb;
+export default createDoubleDb;