how to use canonical functions in Entity Framework and Mysql

Question

how to use canonical functions in Entity Framework and Mysql

c# entity-framework entity-framework-6 mysql

Question

I want to add Timespan to DateTime in EntityFramework with MySql Database.

i have tried using DbFunctions.AddMinutes(someminutes) and EntityFunctions.AddMinutes(someminutes) but when i execute i get exception something like

FUNCTION projectName.AddMinutes does not exist

i have googled but cannot find how to execute canonical function. though there is a list of function but again i don't know which class they belong https://msdn.microsoft.com/en-us/library/bb738563.aspx

I am using

MySql.Data.Entities 6.8.3.0
EntityFramework 6.0.0
MySql.Data 6.8.4
MySql.Web 6.8.4
MySql (Database) 5.6.17

My Linq Query is as below

IQueryable<OrderViewModel> orders = _dbContext.Orders
                         .OrderByDescending(x => x.ID)
                         .Select(x => new OrderViewModel 
                                        { ID = x.ID,
                                          AddedOn = DbFunctions.AddMinutes(x.AddedOn, diffMinutes).Value, 
                                          Customer = (x.IsGuestCheckOut == true ? x.CustomerEmail : x.Customer.FirstName + " " + x.Customer.LastName), 
                                          Phone = x.Phone, 
                                          TotalAmount = x.TotalAmount, 
                                          OrderStatus = x.OrderStatus });

down the road some where condition and pagination is applied

Arjun Vachhani

Popular Answer

AddMinutes method is part of DateTime class, so you can use to instance of DateTime class i.e.

DateTime dateNow = new DateTime.Now;
dateNow.AddMinutes(someminutes);

DbFunctions.AddMinutes(expression, number) this function can only appear within a LINQ to Entities query (https://msdn.microsoft.com/en-us/library/dn220081(v=vs.113).aspx):

Context.Train.Where(x => EntityFunctions.AddMinutes(x.Start, 10) > DateTime.Now)

PatBusz

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Arjun Vachhani · Accepted Answer · 5/15/2015 8:50:52 AM

Actually i misunderstood the error it is not

FUNCTION projectName.AddMinutes does not exist

but

FUNCTION databaseName.AddMinutes does not exist

I don't know what the issue is. Do i have any non-compatible driver/connector , I don't know.

To solve this problem i just created function with name AddMinutes, it calls DATE_ADD() function internally. function definition is as below

CREATE FUNCTION `AddMinutes`(actualDateTime datetime, minutesToAdd int)
RETURNS datetime
BEGIN
    RETURN DATE_ADD(actualDateTime, INTERVAL minutesToAdd MINUTE);
END

I understand that this is not proper solution, but a HACK

how to use canonical functions in Entity Framework and Mysql

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