IDataStore<TModel>.Contains(TModel item) Method

.NET Standard 2.x

Determines whether a data row exists in the primary buffer of the DataStore.

Namespace: DWNet.Data

Assembly: DWNet.Data.dll

Syntax

public bool Contains(TModel item);

Parameters

item TModel

A TModel object which represents a row of data.

Returns

System.Boolean

Returns true if the data row is found in the primary buffer of the DataStore; otherwise, false.

Remarks

A model object which represents a data row is a reference type. The Contains method tests for reference equality (Reference equality means that the object variables that are compared refer to the same object).

It returns true once the item argument and the data row in the primary buffer refer to the same model object. See examples for elaboration.

Examples

The following code example demonstrates how to use the Contains method to determine whether the DataStore contains a particular item.

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

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

        public ContainsExample(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();

            // Creates a D_Department object and populates it with data
            var department = new D_Department
            {
                Departmentid = 10,
                Name = "department name",
                Budget = 10m,
                Startdate = DateTime.Now,
                Administrator = 2
            };

            // The Contains method returns false
            Console.WriteLine("DataStore contains item: {0}",
                datastore.Contains(department));

            // Appends the department data to datastore
            datastore.Add(department);

            // The Contains method returns true
            Console.WriteLine("DataStore contains item: {0}",
                datastore.Contains(department));

            // Changes a data value
            department.Administrator = 3;

            // The Contains method still returns true 
            // because it compares the reference address, not values.
            Console.WriteLine("Datastore contains item {0}",
                datastore.Contains(department));

            /*This code produces the following output:
            
            DataStore contains item: False
            DataStore contains item: True
            DataStore contains item: True     
            */
        }
    }
}

Example Refer To

Model Class: D_Department
DataWindow File: d_department