convert string to an object based on Type

Question

Type type1 = Type.GetType("System.Int32");
string test = "test";

please let me know how to convert the test to an object based on type1 object. And it should fail or return null as the given string cannot be converted to int.

This for validation purpose.

What are you really trying to do? If it is just to see if a string is an int then Boas' answer is correct. This sounds like an X-Y problem — Sayse, Jul 28 '14 at 07:13
Why don't you know the type at compile time? That seems to be the real problem. — Tim Schmelter, Jul 28 '14 at 07:26

score 2 · Answer 1 · edited May 23 '17 at 12:29

2

I'm not quite sure if i understand you right.

if you want to safely convert a string to int see

int result;
bool wasConverted;
wasConverted = int.TryParse(test,out result)

For more generic conversion ahve a look at the ConvertClass.

For Example Convert.ChangeType but there you would have to handle exceptions your own way.

public object SafeConvertChangeType(object value,Type targetType)
      {
      object result ;
      try {
           result = Convert.ChangeType(value, targetType);
      }
      catch (FormatException)
      catch (InvalidCastException) {
           result = null;
      }
return result;
}

you can that call the method this was:

var result = SafeConvertChangeType("Foo",typeof(int32));

You may also have a loot at this post: Test if Convert.ChangeType will work between two types. It points out that there is no "ConversionCheck" Api. So I assumed you would need that exception catch

edited May 23 '17 at 12:29

Community

1
1

answered Jul 28 '14 at 07:11

Boas Enkler

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instead of exception ,is there any other method which returns null if the conversion fails?? – shiv455 Jul 28 '14 at 07:28
i change the example you can wrap it in your own method to do that – Boas Enkler Jul 28 '14 at 08:10
i guess it throws Formatexception when converting string to Int..so need to add catch with formatexception as well??correct me if im wrong?? – shiv455 Jul 28 '14 at 17:19
well it depdends s. MSDN article. In deed both exceptions could occur so you would have to catch both – Boas Enkler Jul 28 '14 at 18:12

score 1 · Answer 2 · answered Jul 28 '14 at 07:13

1

You can use Convert.ChangeType:

Type type1 = Type.GetType("System.Int32");
string test = "test";
object newObject = Convert.ChangeType(test, type1);

answered Jul 28 '14 at 07:13

Patrick Hofman

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Be aware that this throws an exception withi invalid value, he wants to make safe transformations. So you shoul add an try catch (like in my example) – Boas Enkler Jul 28 '14 at 07:14
The question states it should fail or return null. So both allowed. – Patrick Hofman Jul 28 '14 at 07:15
oh yeah sorry my fault. i missread it – Boas Enkler Jul 28 '14 at 07:16
thanks for your answers ,but can you please lemme know if we there is way to return null instead of exception,may not possible with Changetype...but any other way??? – shiv455 Jul 28 '14 at 07:21
Just use a try ... catch. – Patrick Hofman Jul 28 '14 at 07:23
yeah i understood that but instead of exception ,is there any other method which returns null if the conversion fails?? – shiv455 Jul 28 '14 at 07:24
There isn't one. Sorry... – Patrick Hofman Jul 28 '14 at 07:29
@PatrickHofman please lemme know if its possible to know the datatype of the value stored in the test object.... – shiv455 Jul 28 '14 at 07:33
Just call `test.GetType()` – Patrick Hofman Jul 28 '14 at 07:55
1

you can set it to null in the Catch and wrap taht in your on method "SafeChangeType()" s. my post below – Boas Enkler Jul 28 '14 at 08:09

convert string to an object based on Type

2 Answers2