feat(find): Add find feature

We can now search from a specific root to find the first element matching the callback.

It can search in array and objects.

Fixes #17

README.md

@@ -187,7 +187,8 @@ db.getData("/arraytest/lastItemArray[-1]");
 |Can't merge an Array with an Object                    |DataError      |Same idea as the previous message. You have an array as current data and ask to merge it with an Object.                                                                   | 
 |DataPath: /XXX.  YYY is not an array.                  |DataError      |When trying to access an object as an array.                                                                                                                               | 
 |DataPath: /XXX. Can't find index INDEX in array YYY    |DataError      |When trying to access a non-existent index in the array.                                                                                                                   | 
-|Only numerical values accepted for array index         |DataError      |An array can only use number for its indexes. For this use the normal object.                                                                                                            |
+|Only numerical values accepted for array index         |DataError      |An array can only use number for its indexes. For this use the normal object.                                                                                              |
+|The entry at the path (/XXX) needs to be either an Object or an Array        |DataError      |When using the find method, the rootPath need to point to an object or an array to search into it for the wanted value.                              |
 |Can't Load Database:  XXXX                             |DatabaseError  |JsonDB can't load the database for "err" reason. You can find the nested error in **error.inner**                                                                          |
 |Can't save the database: XXX                           |DatabaseError  |JsonDB can't save the database for "err" reason. You can find the nested error in **error.inner**                                                                          | 
 |DataBase not loaded. Can't write                       |DatabaseError  |Since the database hasn't been loaded correctly, the module won't let you save the data to avoid erasing your database.                                                    | 

src/JsonDB.ts

@@ -8,6 +8,9 @@ import {ArrayInfo} from "./lib/ArrayInfo"
 
 type DataPath = Array<string>
 
+
+export type FindCallback = (entry: any, index: number | string) => boolean
+
 export default class JsonDB {
     readonly filename: string
     private loaded: boolean = false
@@ -16,15 +19,21 @@ export default class JsonDB {
     readonly humanReadable: boolean
 
 
-    constructor(filename: string, saveOnPush?: boolean, humanReadable?: boolean) {
+    /**
+     * JSONDB Constructor
+     * @param filename where to save the "DB"
+     * @param saveOnPush save the database at each push command into the json file
+     * @param humanReadable the JSON file will be readable easily by a human
+     */
+    constructor(filename: string, saveOnPush: boolean = true, humanReadable: boolean = false) {
         this.filename = filename
 
         if (!filename.endsWith(".json")) {
             this.filename += ".json"
         }
 
-        this.saveOnPush = typeof(saveOnPush) == "boolean" ? saveOnPush : true
-        this.humanReadable = typeof(humanReadable) == "boolean" ? humanReadable : false
+        this.saveOnPush = saveOnPush
+        this.humanReadable = humanReadable
 
         if (!FS.existsSync(this.filename)) {
             const dirname = path.dirname(this.filename)
@@ -150,14 +159,36 @@ export default class JsonDB {
         }
     }
 
+    /**
+     * Find a specific entry in an array/object
+     * @param rootPath base dataPath from where to start searching
+     * @param callback method to filter the result and find the wanted entry. Receive the entry and it's index.
+     */
+    public find<T>(rootPath: string, callback: FindCallback): T | undefined {
+        const result = this.getData(rootPath)
+        if (Array.isArray(result)) {
+            return result.find(callback) as T
+        }
+        if (result instanceof Object) {
+            const entries = Object.entries(result)
+            const found = entries.find((entry: Array<any>) => {
+                return callback(entry[1], entry[0])
+            })
+            if (!found || found.length < 2) {
+                return undefined
+            }
+            return found[1] as T
+        }
+        throw new DataError("The entry at the path (" + rootPath + ") needs to be either an Object or an Array", 12)
+    }
+
     /**
      * Pushing data into the database
      * @param dataPath path leading to the data
      * @param data data to push
      * @param override overriding or not the data, if not, it will merge them
      */
-    public push(dataPath: string, data: any, override?: boolean): void {
-        override = override === undefined ? true : override
+    public push(dataPath: string, data: any, override: boolean = true): void {
         const dbData = this.getParentData(dataPath, true)
         if (!dbData) {
             throw new Error("Data not found")
@@ -175,7 +206,7 @@ export default class JsonDB {
                 toSet = storedData.concat(data)
             } else if (data === Object(data)) {
                 if (Array.isArray(dbData.getData())) {
-                    throw  new DataError("Can't merge an Array with an Object", 4)
+                    throw new DataError("Can't merge an Array with an Object", 4)
                 }
                 toSet = merge(dbData.getData(), data)
             }

src/lib/DBParentData.ts

@@ -21,10 +21,7 @@ export class DBParentData {
      * Check if it's an array
      * @param deletion
      */
-    private checkArray(deletion?: boolean): ArrayInfo | null {
-        if (typeof deletion === undefined) {
-            deletion = false
-        }
+    private checkArray(deletion: boolean = false): ArrayInfo | null {
         const arrayInfo = ArrayInfo.processArray(this.parent)
         if (arrayInfo && (!arrayInfo.append || deletion) && !arrayInfo.isValid(this.data)) {
             throw new DataError("DataPath: /" + this.dataPath + ". Can't find index " + arrayInfo.index + " in array " + arrayInfo.property, 10)

test/02-jsondb.test.ts

@@ -539,6 +539,31 @@ describe('JsonDB', () => {
             }
         )
     })
+    describe('Find Info', () => {
+        const db = new JsonDB(testFile6, true)
+
+        test('should be able to find the wanted info in object',
+            () => {
+                db.push('/find/id-0', {test: 'hello'})
+                db.push('/find/id-1', {test: 'hey'})
+                db.push('/find/id-2', {test: 'echo'})
+                const result = db.find<string>('/find', entry => entry.test === 'echo')
+                expect(result).toBeInstanceOf(Object)
+                expect(result).toHaveProperty('test', 'echo')
+            })
+        test('should be able to find the wanted info in array',
+            () => {
+                db.push('/find/data', [{test: 'echo'}, {test: 'hey'}, {test: 'hello'}])
+                const result = db.find<string>('/find/data', entry => entry.test === 'hello')
+                expect(result).toBeInstanceOf(Object)
+                expect(result).toHaveProperty('test', 'hello')
+            })
+        test('shouldn\'t be able to find a data in anything else than Object or Array',
+            () => {
+                db.push('/find/number', 1)
+                expect(() => db.find<string>('/find/number', entry => entry.test === 'hello')).toThrow(DataError)
+            })
+    })
 
     describe('Cleanup', () => {
         test('should remove the test files', () => {