(MFC) Firebase GET - Reading Data

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:

Chilkat C/C++ Library Downloads MS Visual C/C++ Libs

See Also: Using MFC CString in Chilkat

#include <CkFileAccess.h>
#include <CkRest.h>
#include <CkAuthGoogle.h>
#include <CkStringBuilder.h>
#include <CkJsonObject.h>

void ChilkatSample(void)
    {
    CkString strOut;

    // 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.

    bool success;

    // Load the previously obtained Firebase access token into a string.
    CkFileAccess fac;
    const char *accessToken = fac.readEntireTextFile("qa_data/tokens/firebaseToken.txt","utf-8");
    if (fac.get_LastMethodSuccess() != true) {
        strOut.append(fac.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    CkRest rest;

    // 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.  
    success = rest.Connect("chilkat.firebaseio.com",443,true,true);
    if (success != true) {
        strOut.append(rest.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    // If authentication is required...
    CkAuthGoogle authGoogle;
    authGoogle.put_AccessToken(accessToken);
    rest.SetAuthGoogle(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.
    const char *jsonResponse = rest.fullRequestNoBody("GET","/pig-rescue/animal.json?shallow=true");
    if (rest.get_LastMethodSuccess() != true) {
        strOut.append(rest.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    // 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}
    strOut.append(jsonResponse);
    strOut.append("\r\n");

    // Parse the response so we can iterate over each pig in the database..
    CkStringBuilder piggyPath;
    CkJsonObject shallow;
    CkJsonObject piggyData;
    shallow.Load(jsonResponse);
    int count = shallow.get_Size();
    int i = 0;
    while (i < count) {

        // Get each individual pig's data.
        piggyPath.Clear();
        piggyPath.Append("/pig-rescue/animal/");
        piggyPath.Append(shallow.nameAt(i));
        piggyPath.Append("/.json");

        const char *piggyJson = rest.fullRequestNoBody("GET",piggyPath.getAsString());
        if (rest.get_LastMethodSuccess() != true) {
            strOut.append(rest.lastErrorText());
            strOut.append("\r\n");
            SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
            return;
        }

        // 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"}
        strOut.append("---- ");
        strOut.appendInt(i);
        strOut.append(" ----");
        strOut.append("\r\n");
        strOut.append(piggyJson);
        strOut.append("\r\n");

        // Let's get the pig's name, and the caption of the picture.
        piggyData.Load(piggyJson);
        strOut.append("name: ");
        strOut.append(piggyData.stringOf("name"));
        strOut.append("\r\n");
        strOut.append("caption: ");
        strOut.append(piggyData.stringOf("picture.caption"));
        strOut.append("\r\n");

        i = 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.  
    // 


    SetDlgItemText(IDC_EDIT1,strOut.getUnicode());

    }