Tcl

Firebase GET - Reading Data

See more Firebase Examples

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:

Tcl

load ./chilkat.dll

set success 0

# 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.
set fac [new_CkFileAccess]

set accessToken [CkFileAccess_readEntireTextFile $fac "qa_data/tokens/firebaseToken.txt" "utf-8"]
if {[CkFileAccess_get_LastMethodSuccess $fac] != 1} then {
    puts [CkFileAccess_lastErrorText $fac]
    delete_CkFileAccess $fac
    exit
}

set rest [new_CkRest]

# 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.  
set success [CkRest_Connect $rest "chilkat.firebaseio.com" 443 1 1]
if {$success != 1} then {
    puts [CkRest_lastErrorText $rest]
    delete_CkFileAccess $fac
    delete_CkRest $rest
    exit
}

# If authentication is required...
set authGoogle [new_CkAuthGoogle]

CkAuthGoogle_put_AccessToken $authGoogle $accessToken
CkRest_SetAuthGoogle $rest $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.
set jsonResponse [CkRest_fullRequestNoBody $rest "GET" "/pig-rescue/animal.json?shallow=true"]
if {[CkRest_get_LastMethodSuccess $rest] != 1} then {
    puts [CkRest_lastErrorText $rest]
    delete_CkFileAccess $fac
    delete_CkRest $rest
    delete_CkAuthGoogle $authGoogle
    exit
}

# 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}
puts "$jsonResponse"

# Parse the response so we can iterate over each pig in the database..
set piggyPath [new_CkStringBuilder]

set shallow [new_CkJsonObject]

set piggyData [new_CkJsonObject]

CkJsonObject_Load $shallow $jsonResponse
set count [CkJsonObject_get_Size $shallow]
set i 0
while {$i < $count} {

    # Get each individual pig's data.
    CkStringBuilder_Clear $piggyPath
    CkStringBuilder_Append $piggyPath "/pig-rescue/animal/"
    CkStringBuilder_Append $piggyPath [CkJsonObject_nameAt $shallow $i]
    CkStringBuilder_Append $piggyPath "/.json"

    set piggyJson [CkRest_fullRequestNoBody $rest "GET" [CkStringBuilder_getAsString $piggyPath]]
    if {[CkRest_get_LastMethodSuccess $rest] != 1} then {
        puts [CkRest_lastErrorText $rest]
        delete_CkFileAccess $fac
        delete_CkRest $rest
        delete_CkAuthGoogle $authGoogle
        delete_CkStringBuilder $piggyPath
        delete_CkJsonObject $shallow
        delete_CkJsonObject $piggyData
        exit
    }

    # 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"}
    puts "---- $i ----"
    puts "$piggyJson"

    # Let's get the pig's name, and the caption of the picture.
    CkJsonObject_Load $piggyData $piggyJson
    puts "name: [CkJsonObject_stringOf $piggyData name]"
    puts "caption: [CkJsonObject_stringOf $piggyData picture.caption]"

    set i [expr $i + 1]
}

# 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.  
# 

delete_CkFileAccess $fac
delete_CkRest $rest
delete_CkAuthGoogle $authGoogle
delete_CkStringBuilder $piggyPath
delete_CkJsonObject $shallow
delete_CkJsonObject $piggyData