How to create a instance of data type known at runtime.

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I have a scenario in which i want to to convert a value in the dataType known at runtime. I have tried hard to solve it but could not find a solution, have a look at the code and guide me... thanx

C#

private void FormatToDbType(SqlDbType dbTp, string value)
        {
            switch (dbTp)
            {
                //BigInt64
                case SqlDbType.BigInt:
                    val = Convert.ToInt64(value);
                    break;
                //Binary
                case SqlDbType.Binary:
                    val = Convert.ToInt64(value);(whatever code)
                    break;
                //Bit
                case SqlDbType.Bit:
                (whatever code);
                break;
                //Char
              }
        }

now i want to pass a value in string and get it out in desired Converted DataType.
what type of variable should i use.
i have tried to use generic aswell
but it gives error

Posted 29-Oct-13 23:14pm

raeeschaudhary

Updated 29-Oct-13 23:16pm

Thomas Daniels

v2

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Comments

BillWoodruff 30-Oct-13 5:54am

Where are you defining the variable 'val and how are you using it ?

raeeschaudhary 30-Oct-13 8:15am

var is not feasible here, i guess

Bheeshm 30-Oct-13 8:24am

In the Method , Change the DataType of "value" variable to dynamic
and you can Get the Type by .... value.GetType().FullName

Bheeshm 30-Oct-13 8:26am

static void Main(string[] args)
{
MyMethod(1);
}

static void MyMethod(dynamic xx )
{
xx.GetType().FullName; //This will give you the Name of the DataType
}

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Sergey Alexandrovich Kryukov · Answer 1 · 2013-10-30T03:51:00

You can do it using reflection. Here is the idea: you get the type and inquire for its constructors. You need to know the purpose of each constructor in advance, so most usually this is done based on parameterless constructor, or some constructor signature you specifically design for this purpose. (Apparently, you want to do it for some set of types. If it was just one type, you would simply hard-code the construction of the object. So, you can create some constructor signature shared by all the types you want to instantiate programmatically and make sure all your types implement it.)

If you simply can use default constructor, you can call System.Activator.CreateInstance:
http://msdn.microsoft.com/en-us/library/wccyzw83.aspx[^].

In more general case, you use one of the reflection methods named "GetConstructor" or "GetConstructors" to get and instance of the class System.Reflection.ConstructorInfo or array of such instances:
http://msdn.microsoft.com/en-us/library/system.type.aspx[^],
http://msdn.microsoft.com/en-us/library/h93ya84h.aspx[^].

If this is the array of System.Reflection.ConstructorInfo instances, you traverse this array to pick one you need, typically by finding out the one with the signature you need, which you can do looking at the list of parameters:
http://msdn.microsoft.com/en-us/library/system.reflection.methodbase.getparameters.aspx[^].

When you found appropriate constructor, you use on of the invoke methods to create an object:
http://msdn.microsoft.com/en-us/library/6ycw1y17.aspx[^],
http://msdn.microsoft.com/en-us/library/a89hcwhh.aspx[^],
http://msdn.microsoft.com/en-us/library/x7xy3xtx.aspx[^],
http://msdn.microsoft.com/en-us/library/4k9x6bc0.aspx[^].

And finally, to use the object as the object of required type, you will need to cast it to required type.

—SA