Convert sql object to valid Json string in node.js - Azure

Question

We are creating a web service in Azure service using node.js to retrieve data from SQL db. We are using ClearDB to do the same.

While retriving the data its not comming in a proper JSON format. How can we convert the result sql object to JSON string.

Below is my code.

app.get('/android', function(request, response) {
    pool.getConnection(function(err, connection) {
        if(err) { handleErrorResponse(err, response); return; }
            var sql = "select projectname from taggedemployee where empname='test@hotmail.com' and tagflag='accepted'"
        connection.query(sql, {}, function(err, results) {
              connection.release(); // always put connection back in pool after last query
          if(err) { handleErrorResponse(err, response); return;  }
                var proj = JSON.stringify(results);
                console.log(proj);
                console.log(proj[0].projectname);
                 for(var myKey in proj) {
                    console.log("key:"+ myKey+", value:"+proj[myKey]);
                 }
          response.setHeader('Content-Type', 'application/json');
          response.status(200).send(JSON.stringify(results) );

        });
    });
});

I cant manipulate the JSON string the returning string is

[{projectname: "Dominos"}]

I tried JSON.stringify but no luck. Please help me to fix this issue

Answer 1

You don't need JSON.stringify() actually. results is already your javascript object, which represents array of json objects. Just use

console.log(results[0].projectname);

Answer 2

The JavaScript Object or Array is JSON, and you need to convert a JSON string to a JavaScript Object thru the function eval or JSON.parse . Please refer to http://www.json.org/js.html .

Answer 3

The response from the SQL service is JSON - as you have shown. You need to use JSON.parse() to parse the JSON into an object. Something like:

app.get('/android', function(request, response) {
    pool.getConnection(function(err, connection) {
        if(err) { handleErrorResponse(err, response); return; }
            var sql = "select projectname from taggedemployee where empname='test@hotmail.com' and tagflag='accepted'"
        connection.query(sql, {}, function(err, results) {
              connection.release(); // always put connection back in pool after last query
          if(err) { handleErrorResponse(err, response); return;  }
                var proj = JSON.parse(response);
                console.log(proj);
          response.setHeader('Content-Type', 'application/json');
          response.status(200).send(results);

        });
    });
});

JSON.stringify is used to convert an object into a JSON string. JSON.parse is used to convert a JSON string into an object.

Answer 4

i built a function to convert the query to JSON, its working very well:

i use Date columns from several tables, it is required to be string (which is fine for me), so these columns will have to be called/contain "Date", other data columns will be float .2f format.

def conv_func(data, columns):
    gen_dict={}
    for j, row in enumerate(data):
        dict = {}
        for col in columns:
            dict[col] = ''
        for i, val in enumerate(dict.keys()):
            if 'Date' in val:
                dict[val]=str(row[i])
            else:
                try:
                    dict[val] = round((row[i]),2)
                except:
                    dict[val]=(row[i])
        gen_dict[j] = dict
    return list(gen_dict.values())

and use the same columns list for the query itself:

def get_tools():
    cur = set_connection()
    columns=['Col1','Col2','Col3']
    columnsQuery=','.join(columns)
    cur.execute(f"SELECT {columnsQuery} FROM [MyTable] ORDER BY [Col1] DESC")
    data = cur.fetchall()
    return {'success': True, 'data': conv_func(data,columns)}