fdb

This chapter describes how to use the fdb library for LuatOS.

Introduction

fbd The library is based on FlashDB and provides the ability to save data on flash. The data storage method is similar to redis’s k-v

Hardware preparation

Any LuatOS-SOC development board

Software part

Interface documentation can be found at:fdb library

Initialize the fdb database before using the fdb library

fdb.kvdb_init("env", "onchip_fdb")

Save Data

The data saving format is key-value

• key is the index of the data

• value For the actual stored data, the type can be.string/number/bool/table

For example：

key	value
data1	“stringData”
data2	1
data3	true
data4	{name=”Jeremy”,age = 18}

The code is as follows

PROJECT = "fdb"
VERSION = "1.0.0"
sys = require("sys")
function test()
    if fdb.kvdb_init("env", "onchip_fdb") == false then
        log.error(PROJECT .. ".kvdb_init", "error")
        return
    end
    log.info(PROJECT .. ".kv_set", fdb.kv_set("data1", "stringData"))
    log.info(PROJECT .. ".kv_set", fdb.kv_set("data2", 1))
    log.info(PROJECT .. ".kv_set", fdb.kv_set("data3", true))
    log.info(PROJECT .. ".kv_set", fdb.kv_set("data4", {
        name = "Jeremy",
        age = 18
    }))
end
sys.taskInit(test)
sys.run()

The log is as follows

I/fal Flash Abstraction Layer (V0.5.0) initialize success.
D/flashdb KVDB size is 65536 bytes.
D/flashdb FlashDB V1.1.0 is initialize success.
D/flashdb You can get the latest version on https://github.com/armink/FlashDB .
I/user.fdb.kv_set true 0
I/user.fdb.kv_set true 0
I/user.fdb.kv_set true 0
I/user.fdb.kv_set true 0

Query data

Read the corresponding data according to the key set in the previous step.

The code is as follows

PROJECT = "fdb"
VERSION = "1.0.0"

sys = require("sys")

function test()
    if fdb.kvdb_init("env", "onchip_fdb") == false then
        log.error(PROJECT .. ".kvdb_init", "error")
        return
    end

    log.info(PROJECT .. ".kv_get", fdb.kv_get("data1"))
    log.info(PROJECT .. ".kv_get", fdb.kv_get("data2"))
    log.info(PROJECT .. ".kv_get", fdb.kv_get("data3"))
    -- data4 is stored in a table
    log.info(PROJECT .. ".kv_get", fdb.kv_get("data4"))
    for k, v in pairs(fdb.kv_get("data4")) do
        print(k, v)
    end
end

sys.taskInit(test)

sys.run()

The log is as follows

I/fal Flash Abstraction Layer (V0.5.0) initialize success.
D/flashdb KVDB size is 65536 bytes.
D/flashdb FlashDB V1.1.0 is initialize success.
D/flashdb You can get the latest version on https://github.com/armink/FlashDB .
I/user.fdb.kv_get stringData
I/user.fdb.kv_get 1
I/user.fdb.kv_get true
I/user.fdb.kv_get table: 200345A8
name Jeremy
age 18

Delete a key

The code is as follows

PROJECT = "fdb"
VERSION = "1.0.0"

sys = require("sys")

function test()
    if fdb.kvdb_init("env", "onchip_fdb") == false then
        log.error(PROJECT .. ".kvdb_init", "error")
        return
    end

    -- Get data previously stored in data1.
    log.info(PROJECT .. ".kv_get", fdb.kv_get("data1"))
    -- delete data stored in data1
    log.info(PROJECT .. ".kv_del", fdb.kv_del("data1"))
    -- Query the data stored in data1 again nil
    log.info(PROJECT .. ".kv_get", fdb.kv_get("data1"))
end

sys.taskInit(test)

sys.run()

The log is as follows

I/fal Flash Abstraction Layer (V0.5.0) initialize success.
D/flashdb KVDB size is 65536 bytes.
D/flashdb FlashDB V1.1.0 is initialize success.
D/flashdb You can get the latest version on https://github.com/armink/FlashDB .
I/user.fdb.kv_get stringData
I/user.fdb.kv_del true
I/user.fdb.kv_get nil

Empty the entire fdb database

The code is as follows

PROJECT = "fdb"
VERSION = "1.0.0"

sys = require("sys")

function test()
    if fdb.kvdb_init("env", "onchip_fdb") == false then
        log.error(PROJECT .. ".kvdb_init", "error")
        return
    end

    -- Query data that still exists
    log.info(PROJECT .. ".kv_get", fdb.kv_get("data2"))
    log.info(PROJECT .. ".kv_get", fdb.kv_get("data3"))
    -- data4 is stored in a table
    log.info(PROJECT .. ".kv_get", fdb.kv_get("data4"))
    for k, v in pairs(fdb.kv_get("data4")) do
        print(k, v)
    end

    -- Empty the entire fdb database
    fdb.kv_clr()

    -- Query the data just queried again
    log.info(PROJECT .. ".kv_get", fdb.kv_get("data2"))
    log.info(PROJECT .. ".kv_get", fdb.kv_get("data3"))
    log.info(PROJECT .. ".kv_get", fdb.kv_get("data4"))
end

sys.taskInit(test)

sys.run()

The log is as follows

I/fal Flash Abstraction Layer (V0.5.0) initialize success.
D/flashdb KVDB size is 65536 bytes.
D/flashdb FlashDB V1.1.0 is initialize success.
D/flashdb You can get the latest version on https://github.com/armink/FlashDB .
I/user.fdb.kv_get 1
I/user.fdb.kv_get true
I/user.fdb.kv_get table: 20034598
name Jeremy
age 18
I/user.fdb.kv_get nil
I/user.fdb.kv_get nil
I/user.fdb.kv_get nil