IDataStore.OnRetrieveStart(object sender, DwRetrieveEventArgs e) Method

.NET Standard 2.x | Current Version (1.0.1)

0.5.0-alpha

1.0.1 (current)

This method is called when the DataStore is about to begin the data retrieval. It triggers the RetrieveStart event by default, and it can be overridden in a child class of the DataStore.

Namespace: PowerBuilder.Data

Assembly: PowerBuilder.Data.dll

Syntax

  public void OnRetrieveStart(object sender, DwRetrieveEventArgs e);

Parameters

sender System.Object

An event sender in which the event occurred.

It is a reference to the current DataStore by default.

e PowerBuilder.Data.DwRowChangeEventArgs

A DwRetrieveEventArgs object which can be used to pass by event arguments.

Remarks

In the RetrieveStart event: To prevent previously retrieved data from being cleared, set DwRetrieveEventArgs.IsResetBuffer to false to allow the current retrieval process to append new rows to the old data; to cancel the retrieval, set DwRetrieveEventArgs.IsCancel to true.

Examples

The following code example gets the RowCount value when Retrieve is about to begin and when it is completed.

using PowerBuilder.Data;
using System;

namespace Appeon.ApiDoc.IDataStoreExamples
{
    public class OnRetrieveStartExample
    {
        private SchoolContext _context;

        public OnRetrieveStartExample(SchoolContext dataContext)
        {
            // Sets the data context
            _context = dataContext;
        }

        public void Example()
        {
            // Instantiates a DataStore object with datawindow: d_department.
            var datastore = new DataStore("d_department", _context);

            // Defines what to do when Retrieve is about to begin
            datastore.RetrieveStart +=
                (sender, args) =>
                {
                    // Executes the following code before Retrieve is executed 
                    Console.WriteLine("Before Retrieve, Rowcount: {0}",
                        args.RowCount);
                };

            // Retrieves rows from the database for datastore.
            // OnRetrieveStart method is called internally to invoke the 
            // RetrieveEnd event.
            datastore.Retrieve();

            Console.WriteLine("After Retrieve, Rowcount: {0}",
                datastore.RowCount);

            /*This code produces the following output:
            
            Before Retrieve, Rowcount: 0
            After Retrieve, Rowcount: 4           
            */
        }
    }
}

Example Refer To

Model Class: D_Department
DataWindow File: d_department

Applies to

.NET Standard

2.x