IDataStore.Sum<TModel>(Func<TModel, decimal> selector, Predicate<TModel> predicate) Method

.NET Standard 2.x

Computes the sum of a sequence of decimal values that are obtained by invoking a transform function on each row (filtered by a Predicate<TModel> object) of the primary buffer in DataStore.

Namespace: DWNet.Data

Assembly: DWNet.Data.dll

Syntax

  public decimal Sum<TModel>(Func<TModel, decimal> selector, Predicate<TModel> predicate);

Type Parameters

TModel

The type of a model class that matches with the current DataObject.

Parameters

selector System.Func<TModel,System.Decimal>

A transform function to apply to each row.

predicate System.Predicate<TModel>

A function to evaluate each row in the primary buffer for a condition.

Returns

System.Decimal

The sum of the sequence of values.

Examples

The following code example calculates the sum of those values (which are greater than 200000) in the budget column.

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

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

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

        public void Example2()
        {
            // Instantiates a DataStore object with datawindow: d_department.
            var datastore = new DataStore("d_department", _context);

            // Retrieves rows from the database for datastore.
            datastore.Retrieve();

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

            // Calculates the sum of budget whose value is greater than 200000.
            decimal sumvalue = datastore.Sum<D_Department>(
                m => m.Budget,
                m => m.Budget > 200000);

            Console.WriteLine("The sum of budget greater than 200000 is: {0}",
                sumvalue);

            /*This code produces the following output:
            
            After Retrieve, Rowcount: 4
            The sum of budget greater than 200000 is: 470000.0000
            */
        }
    }
}

Example Refer To

Model Class: D_Department
DataWindow File: d_department

Applies to

.NET Standard

2.x