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README.md
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README.md
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FlatDB
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===========
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FlatDB is a lua library that implements a serverless, zero-configuration, NoSQL database engine.<br>
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It provides a key-value storage system using plain Lua tables.
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When To Use FlatDB
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===========
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When you want to use SQLite to store data, just take a glance at FlatDB.<br>
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When Lua acts in your program as the major language or the embedded scripting language, just try using FlatDB.
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Usage
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==========
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Copy *flatdb.lua* file to your project or where your lua libraries stored.<br>
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Then write this in any Lua file where you want to use it:
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```lua
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local flatdb = require 'flatdb'
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```
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FlatDB
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===========
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FlatDB is a lua library that implements a serverless, zero-configuration, NoSQL database engine.<br>
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It provides a key-value storage system using plain Lua tables.
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When To Use FlatDB
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===========
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When you want to use SQLite to store data, just take a glance at FlatDB.<br>
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When Lua acts in your program as the major language or the embedded scripting language, just try using FlatDB.
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Concept
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==========
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| FlatDB | Disk | Lua |
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|:--------------:|:-------------:|:--------------:|
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| Database | Directory | Table |
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| Book | File | Table |
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| Key-value pair | File content | Key-value pair |
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Keys and values can be all Lua types except coroutines, userdata, cdata and C functions.
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Usage
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==========
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Copy *flatdb.lua* file to your project or where your lua libraries stored.<br>
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Then write this in any Lua file where you want to use it:
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```lua
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local flatdb = require 'flatdb'
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```
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1. Bind a directory as a database
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```lua
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local db = flatdb('./db')
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```
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```lua
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local db = flatdb('./db')
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```
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2. Open or create a book
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```lua
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if not db.book then
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db.book = {}
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end
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```
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```lua
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if not db.book then
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db.book = {}
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end
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```
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3. Store key-value items
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```lua
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db.book.key = 'value'
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-- equivalent to db.book['key'] = 'value'
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```
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```lua
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db.book.key = 'value'
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-- equivalent to db.book['key'] = 'value'
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```
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4. Retrieve items
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```lua
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print(db.book.key) -- prints 'value'
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```
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```lua
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print(db.book.key) -- prints 'value'
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```
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5. Save to file
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```lua
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db:save()
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-- 'book' will be saved to './db/book'
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```
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More usage can be found in the *cli.lua*(a Redis-like command line interface example using FlatDB).
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Quick Look
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==========
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```lua
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local flatdb = require("flatdb")
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-- open a directory as a database, 'db' is just a plain empty Lua table that can contain books
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local db = flatdb("./db")
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-- open or create a book named "default", it also a plain empty Lua table where key-value data stored in
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if not db.default then
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db.default = {}
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end
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-- extend db methods for getting values from 'default' book
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flatdb.hack.get = function(db, key)
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return db.default[key]
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end
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-- extend db methods for setting values to 'default' book
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flatdb.hack.set = function(db, key, value)
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db.default[key] = value
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end
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-- extend db methods for watching new key
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flatdb.hack.guard = function(db, f)
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setmetatable(db.default, {__newindex = f})
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end
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-- get key-value data from 'default' book
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print(db:get("hello"))
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-- set key-value data to 'default' book
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db:set("hello", "world")
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-- get key-value data from 'default' book
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print(db:get("hello"))
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-- set guard function
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db:guard(function(book, key, value)
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print("CREATE KEY permission denied!")
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end)
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-- try creating new key-value data to 'default' book
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db:set("key1", 1)
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db:set("key2", 2)
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-- update an existing key-value item
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db:set("hello", "bye")
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print(db:get("key1")) -- prints nil
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print(db:get("key2")) -- prints nil
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print(db:get("hello")) -- prints 'bye'
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-- store 'default' book to './db/default' file
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db:save()
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```
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API
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==========
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- **Functions**
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- **flatdb(dir) --> db**
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Bind a directory as a database, returns nil if 'dir' doesn't exists. Otherwise, it returns a 'db' obeject.
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- **db:save([book])**
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Save all books or the given book(if specified) contained in db to file. The 'book' argument is a string, the book's name.
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- **Tables**
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- **flatdb.hack**
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The 'hack' table contains db's methods. There is only one method 'save(db, book)' in it by default.
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It is usually used to extend db methods.
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Dependencies
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=======
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- [pp](https://github.com/luapower/pp)
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- [lfs](http://keplerproject.github.io/luafilesystem/)
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All above libraries can be found in [LuaPower](https://luapower.com/).
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License
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=======
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FlatDB is distributed under the MIT license.
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```lua
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db:save()
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-- 'book' will be saved to './db/book'
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```
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More usage can be found in the *cli.lua*(a Redis-like command line interface example using FlatDB).
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Quick Look
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==========
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```lua
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local flatdb = require("flatdb")
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-- open a directory as a database
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-- 'db' is just a plain empty Lua table that can contain books
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local db = flatdb("./db")
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-- open or create a book named "default"
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-- it is also a plain empty Lua table where key-value pair stored in
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if not db.default then
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db.default = {}
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end
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-- extend db methods for getting values from 'default' book
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flatdb.hack.get = function(db, key)
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return db.default[key]
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end
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-- extend db methods for setting values to 'default' book
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flatdb.hack.set = function(db, key, value)
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db.default[key] = value
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end
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-- extend db methods for watching new key
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flatdb.hack.guard = function(db, f)
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setmetatable(db.default, {__newindex = f})
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end
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-- get key-value data from 'default' book
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print(db:get("hello"))
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-- set key-value data to 'default' book
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db:set("hello", "world")
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-- get key-value data from 'default' book
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print(db:get("hello"))
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-- set guard function
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db:guard(function(book, key, value)
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print("CREATE KEY permission denied!")
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end)
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-- try creating new key-value pair to 'default' book
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db:set("key1", 1)
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db:set("key2", 2)
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-- update an existing key-value pair
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db:set("hello", "bye")
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print(db:get("key1")) -- prints nil
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print(db:get("key2")) -- prints nil
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print(db:get("hello")) -- prints 'bye'
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-- store 'default' book to './db/default' file
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db:save()
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```
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API
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==========
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- **Functions**
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- **flatdb(dir) --> db**
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Bind a directory as a database, returns nil if 'dir' doesn't exists. Otherwise, it returns a 'db' obeject.
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- **db:save([book])**
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Save all books or the given book(if specified) contained in db to file. The 'book' argument is a string, the book's name.
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- **Tables**
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- **flatdb.hack**
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The 'hack' table contains db's methods. There is only one method 'save(db, book)' in it by default.
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It is usually used to extend db methods.
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Dependencies
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=======
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- [pp](https://github.com/luapower/pp)
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- [lfs](http://keplerproject.github.io/luafilesystem/)
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All above libraries can be found in [LuaPower](https://luapower.com/).
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License
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=======
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FlatDB is distributed under the MIT license.
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