CODEWITHSUNDEEP
c#
user3170203
user3170203

Reputation: 3

Building condition to do filtering later

The goal is to have some code to build filtering condition for Where call.

In FoxPro I'd use condition built as string ("foo == 3 && bar > 5") and execute it later.

I am trying similar approach in C# - create string and use it as condition in the code below but can't find way to do it:

string Condition = "";

...
if (xyz > 0)
    Condition = "scr.ZipCode = 12345";

if (xyz > 1)
    Condition = "scr.ZipCode = 23456";

if (xyz > 2)
    Condition = "scr.ZipCode = 34567";

...etc.

and then use it in the code:

var shippingShipCalculatorRecords = 
   _shippingShipCalculatorService.GetAllShippingShipCalculatorRecords()
            .Where(scr => (
                              (scr.CountryId == 0 && Condition)
                          )
            .OrderBy(x => x.Sequence).ToList();

I've tried to convert it to bool but it didn't work neither. I use to work in FoxPro and could easily achieve it (&Condition).

Upvotes: 0

Views: 135

Answers (2)

Pierre-Luc Pineault
Pierre-Luc Pineault

Reputation: 9201

Sorry, but AFAIK I'm afraid you can't do that. However, you can hold on the zip code in a variable and use it later in your condition :

string zipcode = string.Empty; //Or an int, if it is stored like so

if (xyz > 0)
    zipcode = "12345";

if (xyz > 1)
    zipcode = "23456";

if (xyz > 2)
    zipcode = "34567";

So your condition will now be 

(scr.CountryId == 0 && src.ZipCode == zipcode)

Upvotes: 2

Servy
Servy

Reputation: 203835

Rather than making your condition a string, have it be an Expression<Func<YourEntityType, bool>> so that you can still have compile time verification that your syntax is all valid:

Expression<Func<YourEntityType, bool>> Condition;

if (xyz > 0)
    Condition = scr => scr.ZipCode == 12345;
else if (xyz > 1)
    Condition = scr => scr.ZipCode == 23456;
else if (xyz > 2)
    Condition = scr => scr.SomeOtherField == "someStringValue";
else 
    Condition = scr => true; //or whatever makes sense as a default choice

var shippingShipCalculatorRecords = 
    _shippingShipCalculatorService.GetAllShippingShipCalculatorRecords()
            .Where(scr => scr.CountryId == 0)
            .Where(Condition)
            .OrderBy(x => x.Sequence).ToList();

Upvotes: 7

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