Retrieving SPList Data From SharePoint Online Site using CSOM

using Microsoft.SharePoint.Client;

using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Linq;

using System.Security;

using System.Text;

using System.Threading.Tasks;

using System.Windows.Forms;

namespace SPOnlineDataAccess

{

    public partial class Form1 : System.Windows.Forms.Form

    {

        public Form1()

        {

            InitializeComponent();

        }

        private void LoadDefaultValues()

        {

            txtSiteUrl.Text = "https://abc.sharepoint.com/sites/testsite";

            txtListName.Text = "OnlineList";

            txtUserEmail.Text = "user1@xyz.com";

            txtPassword.Text = "pass@123qaz";

        }

        private void btnLoad_Click(object sender, EventArgs e)

        {

            DataTable dtResults = ReadSPList();

            dataGridView1.DataSource = dtResults;

        }

        private DataTable ReadSPList()

        {

            using (ClientContext clientContext = GetContextObject())

            {

                try

                {

                    DataTable dtListData = new DataTable();

                    //Creating DataTable Columns

                    dtListData.Columns.Add("Title", typeof(String));

                    dtListData.Columns.Add("Designation", typeof(String));

                    dtListData.Columns.Add("EmpID", typeof(String));

                    //Getting Data From SharePoint

                    Web web = clientContext.Web;

                    clientContext.Load(web, website => website.ServerRelativeUrl);

                    clientContext.ExecuteQuery();                  

                    //Read SPList called "OnlineList"

                    List myList = web.Lists.GetByTitle(txtListName.Text);

                    // This creates a CamlQuery that has a RowLimit of 1000, and also specifies Scope="RecursiveAll"

                    // so that it grabs all list items, regardless of the folder they are in.

                    CamlQuery query = CamlQuery.CreateAllItemsQuery(1000);

                    ListItemCollection items = myList.GetItems(query);

                    // Retrieve all items in the ListItemCollection from List.GetItems(Query).

                    clientContext.Load(items);

                    clientContext.ExecuteQuery();

                    for (int count = 0; count < items.Count; count++)

                    {

                        DataRow dr = dtListData.NewRow();

                        dr["Title"] = items[count]["Title"].ToString();

                        dr["Designation"] = items[count]["Designation"].ToString();

                        dr["EmpID"] = items[count]["EmpID"].ToString();

                        dtListData.Rows.Add(dr);

                    }

                    return dtListData;

                }

                catch (Exception ex)

                {

                    MessageBox.Show(ex.Message);

                    return null;

                }

            }

        }

        private ClientContext GetContextObject()

        {

            string siteUrl = txtSiteUrl.Text;

            string userName = txtUserEmail.Text;

            string password = txtPassword.Text;

            SecureString _password = GetPasswordFromInput(password);

            ClientContext context = new ClientContext(siteUrl);

            context.Credentials = new SharePointOnlineCredentials(userName, _password);

            return context;

        }

        private void Form1_Load(object sender, EventArgs e)

        {

            LoadDefaultValues();

        }

        private SecureString GetPasswordFromInput(string password)

        {

            //Get the user's password as a SecureString

            SecureString securePassword = new SecureString();

            char[] arrPassword = password.ToCharArray();

            foreach (char c in arrPassword)

            {

                securePassword.AppendChar(c);

            }

            return securePassword;

        }

    }

}

Content Editor WebPart With CSOM

Im writing simple code to save data to LIST using CSOM, include in CEWP.

The Code of full file that can be bounded to CEWP.

=======================================================================

<div onkeydown='javascript:if (event.keyCode == 13) postSurvey()'>
    <p>1. How is the weather?<br />
         <input name='q1' id='q1Bad' type='radio' value='Bad'/><label for='q1Bad'> Bad</label><br />
         <input name='q1' id='q1Good' type='radio' value='Good'/><label for='q1Good'> Good</label><br />
         <input name='q1' id='q1Great' type='radio' value='Great'/><label for='q1Great'> Great</label>
    </p>
    <p>2. How are you doing?<br />
         <input name='q2' id='q2Fine' type='radio' value='Fine'/> <label for='q2Fine'>Fine</label><br />
         <input name='q2' id='q2Good' type='radio' value='Good' /><label for='q2Good'> Good</label><br />
         <input name='q2' id='q2Great' type='radio' value='Great' /><label for='q2Great'> Great</label>
    </p>
    <input type='button' value='Submit' onclick='javascript:postSurvey();' />

</div>

/*
These 2 files are really important, The Order is also important
*/

<script type="text/javascript" src="/_layouts/15/sp.runtime.js"></script>
<script type="text/javascript" src="/_layouts/15/sp.js" ></script>

<script language='javascript' type='text/javascript'>
        function getCheckedValue(buttonGroup) {
            if (!buttonGroup)
                return '';
            var objLength = buttonGroup.length;
            if (objLength == undefined) {
                if (buttonGroup.checked)
                    return buttonGroup.value;
                else
                     return '';
            }
            for (var i = 0; i < objLength; i++) {
                if (buttonGroup[i].checked)
                    return buttonGroup[i].value;
            }
            return '';
        }
     
        function postSurvey() {
       
            // Retrieve the radio button values

            var question1 = getCheckedValue(document.getElementsByName('q1'));
            var question2 = getCheckedValue(document.getElementsByName('q2'));

            /* Validate the response.
               Do nothing more until all questions are answered.
            */
            if (question1 == '' || question2 == '') {
                alert('Please answer all questions.')
                return;
            }

// Get the current context
           var context = new SP.ClientContext.get_current();

           // Get the current site (SPWeb)
           var web = context.get_web();

           // Get the survey list
           var list = web.get_lists().getByTitle('SampleSurvey');

           // Create a new list item
           var itemCreateInfo = new SP.ListItemCreationInformation();
           var listItem = list.addItem(itemCreateInfo);

           /* Set fields in the item.
              In managed code, this would be listItem[fieldname] = value.
              In Javascript, call listItem.set_item(fieldName,value).
           */
           listItem.set_item('How_x0020_is_x0020_the_x0020_wea', question1);
           listItem.set_item('How_x0020_are_x0020_you_x0020_do', question2);
           listItem.update();

           // Create callback handlers
           var success = Function.createDelegate(this, this.onSuccess);
           var failure = Function.createDelegate(this, this.onFailure);

           // Execute an async query
           context.executeQueryAsync(success,failure);

        }

// Async query succeeded.
function onSuccess(sender, args) {

    alert('Thank you for responding to our survey!');
     
    // Refresh the page.
    SP.UI.ModalDialog.RefreshPage(SP.UI.DialogResult.OK);
}

// Async query failed.
function onFailure(sender, args) {
    alert(args.get_message());
}
    </script>