Creating an anonymous object depending on parameters

Question

To simplify the problem, I suppose that I have a method with two boolean parameters getParamA and getParamB.

public JsonResult MyMethod(bool getParamA, bool getParamB)

Is There a way like a ternary operator or something to say if getParamA == true and getParamB == false for example, I create an anonymous object like this :

//this is an entityframework query 
var result = entityContext.MyTable.Select(r=> new 
{ 
      paramA = r.paramA // because getParamA = true
      // don't create paramB because getParamB is false  
});

I know it is easy to implement this using two parameters (using if else condition) but things are getting complicated if we have more than 5 paramters (because you need to do all the testing)...

Patrick Hofman · Accepted Answer · 2017-06-21 12:46:33Z

1

You can, but it isn't really efficient code. It makes your code a complete mess:

.Select( r => getParamA && getParamB
              ? (object)new { A = r.A, B = r.B }
              : (getParamA ? new { A = r.A }
                           : (getParamB ? new { B = r.B }
                                        : null
                             )
                )
       );

A better option might be the ExpandoObject, which uses a dictionary internally to store its properties and values.

dynamic eo = new ExpandoObject();

if (getParamA)
{
    eo.A = r.A;
}

if (getParamB)
{
    eo.B = r.B;
}

edited Jun 21, 2017 at 12:46

answered Jun 21, 2017 at 12:44

Patrick Hofman

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13 Comments

Patrick Hofman Over a year ago

Well, you are asking if it is possible, the answer is yes. Should you do it? No.

Patrick Hofman Over a year ago

@MehdiSouregi ExpandoObject then?

Mehdi Souregi Over a year ago

Thanks, is it possible to implement it within the lambda expression above?

Mehdi Souregi Over a year ago

Wow, as the answerer said in your link, the implmentation is too overcomplicated :p so I am going to get all the columns and for my case it happens to be that all the parameters on the entry are the exact same parameters on the table. I can not use ExpandoObject for my case because it is not serializable, so maybe i am going to use an IDictionnary

Evk Over a year ago

@MehdiSouregi ExpandoObject is serializable to json (for example by JSON.NET). Besides - it already implements IDictionary<string, object>.

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