IDataStore<TModel>.Exists(Predicate<TModel> predicate, DwBuffer bufferType = DwBuffer.Primary) Method

.NET Standard 2.x

Determines whether there is a row in the primary buffer of the DataStore that meets the specified condition.

Namespace: DWNet.Data

Assembly: DWNet.Data.dll

Syntax

bool Exists(Predicate<TModel> predicate, DwBuffer bufferType = DwBuffer.Primary);

Parameters

predicate Predicate<TModel>

A Predicate<TModel> object that you want to use as the search criteria.

bufferType DWNet.Data.DwBuffer

The buffer in which to find row.

It is specified to the primary buffer by default.

Returns

System.Boolean

Returns true if there is a row in the primary buffer that meets the specified condition, otherwise, false.

Examples

The following code example demonstrates how to use the Exists method to determine whether there are records in the DataStore that meet the criteria.

using Appeon.ApiDoc.Models;
using DWNet.Data;
using System;

namespace Appeon.ApiDoc.IDataStore_GenericExamples
{
    public class ExistsExample
    {
        private readonly SchoolContext _context;

        public ExistsExample(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);

            datastore.Retrieve();
            
            // No record in datastore whose Name="Department New"
            bool exists = datastore.Exists(a => a.Name == "Department New");

            Console.WriteLine("Department New: {0}", exists);

            // There is a record in datastore whose Name="Engineering"
            exists = datastore.Exists(a => a.Name == "Engineering");
            Console.WriteLine("Engineering: {0}", exists);

            /*This code produces the following output:
            
            Department New: False
            Engineering: True    
            */
        }
    }
}

Example Refer To

Model Class: D_Department
DataWindow File: d_department