Lua

Firebase GET - Reading Data

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Demonstrates how to read parts of a Firebase JSON database. The data used in this example is at Chilkat Firebase Pigs Database, and is shown here:

Lua

local chilkat = require("chilkat")

-- Demonstrates how to read parts of a Firebase JSON database.

-- This example requires the Chilkat API to have been previously unlocked.
-- See Global Unlock Sample for sample code.

-- This example assumes a JWT authentication token, if required, has been previously obtained.
-- See Get Firebase Access Token from JSON Service Account Private Key for sample code.

-- Load the previously obtained Firebase access token into a string.
local fac = chilkat.FileAccess.new()
local accessToken = fac:read_entire_text_file("qa_data/tokens/firebaseToken.txt", "utf-8")
if not fac.last_method_success then
    print(fac.last_error_text)
    return
end

local rest = chilkat.Rest.new()

-- Make the initial connection (without sending a request yet).
-- Once connected, any number of requests may be sent.  It is not necessary to explicitly
-- call Connect before each request.
local success = rest:connect("chilkat.firebaseio.com", 443, true, true)
if not success then
    print(rest.last_error_text)
    return
end

-- If authentication is required...
local authGoogle = chilkat.AuthGoogle.new()
authGoogle.access_token = accessToken
rest:set_auth_google(authGoogle)

-- Chilkat's sample data (pig-rescue data) is publicly readable at: https://chilkat.firebaseio.com/.json

-- Let's get the animals with the shallow parameter so we can see how many pigs exist.
local jsonResponse = rest:full_request_no_body("GET", "/pig-rescue/animal.json?shallow=true")
if not rest.last_method_success then
    print(rest.last_error_text)
    return
end

-- The JSON returned should look like this:
-- {"-KI3bD-FU_Dake7sYOiP":true,"-KI3bD-FU_Dake7sYOiT":true,"-KI3bD-FU_Dake7sYOiS":true,"-KI3bD-FU_Dake7sYOiU":true,"-KI3bD-FU_Dake7sYOiV":true,"-KI3bD-FU_Dake7sYOiR":true,"-KI3bD-FU_Dake7sYOiQ":true}
print(jsonResponse)

-- Parse the response so we can iterate over each pig in the database..
local piggyPath = chilkat.StringBuilder.new()
local shallow = chilkat.JsonObject.new()
local piggyData = chilkat.JsonObject.new()
shallow:load(jsonResponse)
local count = shallow.size
local i = 0
while i < count do
    -- Get each individual pig's data.
    piggyPath:clear()
    piggyPath:append("/pig-rescue/animal/")
    piggyPath:append(shallow:name_at(i))
    piggyPath:append("/.json")

    local piggyJson = rest:full_request_no_body("GET", piggyPath:get_as_string())
    if not rest.last_method_success then
        print(rest.last_error_text)
        return
    end

    -- Show this piggy's data...
    -- An example of one pig's data is shown here:
    -- {"birth":"February, 1998","from":"Middle Ave.","gender":"F","in-date":"January, 2000",
    --   "name":"Molly II","picture":{"caption":"Molly in the Pasture","description":"Black pig","file":"molly_th.jpg"},
    --   "species":"pot belly pig","type":"Cathy's Herd"}
    print("---- " .. i .. " ----")
    print(piggyJson)

    -- Let's get the pig's name, and the caption of the picture.
    piggyData:load(piggyJson)
    print("name: " .. piggyData:string_of("name"))
    print("caption: " .. piggyData:string_of("picture.caption"))

    i = i + 1
end

-- Note: In many of the Chilkat examples, you may notice strange ways
-- of doing something that should be simpler and shorter.  For example,
-- building the piggyPath (above) could've been written differently,
-- with some simple string concatenation.
--
-- The reason is that the Chilkat examples are written in a
-- proprietary "example code" scripting language,
-- and then automatically generated to each of the different programming
-- languages you see on example-code.com.  The code generation is
-- limited in what it can do.  For example, string concatentation
-- is not yet a feature of the "example code" scripting language (as of May 2016),
-- and therefore you won't see the use of a programming language's string
-- concatentation operators in any example.
--