Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>The answer is a big YES. You're trying to exploit the existence of the static T.TryParse(string, out T) function on the types you're converting to, and we can do that pretty easily with a little reflection. </p> <pre><code>public static T? ParseOrNull&lt;T&gt;(this string str) where T: struct, IConvertible { // find the TryParse method. var parseMethod = typeof(T).GetMethod("TryParse", // We want the public static one BindingFlags.Public | BindingFlags.Static, Type.DefaultBinder, // where the arguments are (string, out T) new[] { typeof(string), typeof(T).MakeByRefType() }, null); if (parseMethod == null) // You need to know this so you can parse manually throw new InvalidOperationException( string.Format("{0} doesn't have a TryParse(..) function!", typeof(T).FullName)); // create the parameter list for the function call var args = new object[] { str, default(T) }; // and then call the function. if ( (bool)parseMethod.Invoke(null, args)) return (T?)args[1]; // if it returned true // if it returned false return null; } </code></pre> <p>This is the original answer I provided, based on the idea that you need two different parse methods: One for value types and another for reference types.</p> <pre><code> public delegate bool ParseDelegate&lt;T&gt;(string s, out T result); public static T? ParseOrNull&lt;T&gt;(this string str, ParseDelegate&lt;T&gt; Parse) where T: struct { T result; if (!Parse(str, out result)) return null; return result; } public static T ParseOrNull&lt;T&gt;(this string str, ParseDelegate&lt;T&gt; Parse) where T : class { T result; if (!Parse(str, out result)) return null; return result; } </code></pre>
    singulars
    1. This table or related slice is empty.
    1. POHow to write generic extension methods?
      singulars
      1. PTQuestion
    1. PTAnswer
    1. USCodeGnome
    1. USCodeGnome
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    1. This table or related slice is empty.
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload