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Chart.Js with webmethod and data from sql server

Question

User2015884762 posted

I am new to the charting feature and web methods as well. Anyhow, I have googled and I managed to come up with this, it's not working at all.

Appreciate if someone can point out what I am missing. Basically, my data is in sql server and I am trying to pull the data into a pie..( just a test I am running before I move on the real project). I found the code at this link https://stackoverflow.com/questions/54884956/pie-chart-using-chart-js-and-asp-net-web-service-asmx - I modified it with the data in my sql..

So this is the code.

This is the Chartnew.aspx page

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Chartnew.aspx.cs" Inherits="ChartTest.Chartnew" %>

<!DOCTYPE html>

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
   
    <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>
    <script src="//cdn.jsdelivr.net/excanvas/r3/excanvas.js" type="text/javascript"></script>
     <script src="Scripts/Chart.js"></script>
    <title></title>
</head>
<body>
    <form id="form1" runat="server">
        <div id="canvas-holder" style="width:40%">
    <canvas id="chart-area"></canvas>
</div>
    </form>
    <script src="Scripts/JavaScript.js"></script>
</body>
</html>

This is the code behind page.

using System;
using System.Collections.Generic;
using System.Configuration;
using System.Data;
using System.Data.SqlClient;
using System.Linq;
using System.Text;
using System.Web;
using System.Web.Script.Serialization;
using System.Web.Services;
using System.Web.UI;
using System.Web.UI.WebControls;

namespace ChartTest
{
    public partial class Chartnew : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {

        }

       
       

        [WebMethod]
        public void GetTotalPhoneSales()
        {
            string cs = ConfigurationManager.ConnectionStrings["ConString"].ConnectionString;
            List<TotalSales> totalSales = new List<TotalSales>();
            using (SqlConnection con = new SqlConnection(cs))
            {
                SqlCommand cmd = new SqlCommand("Sales by Year", con)
                {
                    CommandType = CommandType.StoredProcedure
                };
                con.Open();
                SqlDataReader rdr = cmd.ExecuteReader();
                while (rdr.Read())
                {
                    TotalSales PhoneSale = new TotalSales
                    {
                        Amount = Convert.ToDouble(rdr["Subtotal"]),
                        Year = Convert.ToInt32(rdr["Year"])
                    };
                    totalSales.Add(PhoneSale);
                }
            }
            JavaScriptSerializer js = new JavaScriptSerializer();
            Context.Response.Write(js.Serialize(totalSales));
        }
    }


    class TotalSales
    {
        public double Amount;
        public int Year;
    }
}

This is the external JavaScript file.

console.log('Hello');
var chartLabel = [];
var chartData = [];

$.ajax({
    alert: ("It has ended"),
    url: 'Chartnew.aspx/GetTotalPhoneSales',
    method: 'post',
    dataType: 'json',
    
    success: function (data) {

        $(data).each(function (index, item) {
            chartLabel.push(item.Year);
            chartData.push(item.Amount);
        });

    },
    error: function (err) {
        alert(err);
    }
});




var config = {
    type: 'pie',
    data: {
        datasets: [{
            data: chartData,
            backgroundColor: [
                "#3e95cd", "#8e5ea2", "#3cba9f"
            ],
            label: 'Labels'
        }],
        labels: chartLabel
    },
    options: {
        responsive: true
    }
};

window.onload = function () {
    var ctx = document.getElementById('chart-area').getContext('2d');
    window.myPie = new Chart(ctx, config);
};

Monday, April 5, 2021 4:07 AM

Answers

User-1330468790 posted

Hi callykalpana,

Thank you for providing codes which makes the troubleshooting more efficient.

Actually, there are some mistakes in the codes.

Miss "static" in [WebMethod] of the code behind method.
Miss <contentType: "application/json; charset=utf-8"> in ajax parameter.
Put the codes "new Chart(ctx, config)" in a wrong place.
Wrongly return the result from [WebMethod].
Wrongly fetch data from success function.

More details, you could refer to below codes.

aspx:

 <form id="form1" runat="server">
        <div id="canvas-holder" style="width: 40%">
            <canvas id="chart-area"></canvas>
        </div>
    </form>
    <script>
        console.log('Hello');
        var chartLabel = [];
        var chartData = [];

        $.ajax({
            alert: ("It has ended"),
            url: 'Chartnew.aspx/GetTotalPhoneSales',
            method: 'post',
            dataType: 'json',
            contentType: "application/json; charset=utf-8",
            success: function (data) {
                // Get json data from d, check it from dev-tools => Press F12
                data = JSON.parse(data.d);
                
                $(data).each(function (index, item) {
                    chartLabel.push(item.Year);
                    chartData.push(item.Amount);
                });

                // Set the data from here
                var config = {
                    type: 'pie',
                    data: {
                        datasets: [{
                            data: chartData,
                            backgroundColor: [
                                "#3e95cd", "#8e5ea2", "#3cba9f"
                            ],
                            label: 'Labels'
                        }],
                        labels: chartLabel
                    },
                    options: {
                        responsive: true
                    }
                };

                // Initial Chart in ajax success function
                var ctx = document.getElementById('chart-area').getContext('2d');
                window.myPie = new Chart(ctx, config);

            },
            error: function (err) {
                alert(err);
            }
        });
        
        window.onload = function () {
           
        };
    </script>

Code behind: (Data Simulation)

public partial class Chartnew : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {

        }

        [WebMethod]
        public static string GetTotalPhoneSales()
        {
            List<TotalSales> totalSales = new List<TotalSales>();

            for (int i = 0; i < 3; i++) {
                TotalSales PhoneSale = new TotalSales
                {
                    Amount = Convert.ToDouble(i+100),
                    Year = Convert.ToInt32(i+2020)
                };
                totalSales.Add(PhoneSale);
            }
            
            JavaScriptSerializer js = new JavaScriptSerializer();
            
            return js.Serialize(totalSales);
        }
    }

    class TotalSales
    {
        public double Amount;
        public int Year;
    }

Demo:

Hope helps.

Best regards,

Sean

Marked as answer by Anonymous Thursday, October 7, 2021 12:00 AM

Tuesday, April 6, 2021 9:36 AM

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