Databases
StackOverflow2013
Postsdbo
POC#: How to Implement and use a NotNull and CanBeNull attribute
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POC#: How to Implement and use a NotNull and CanBeNull attribute
    primarykey
    data
    text
    <p>I want to let programmers and myself know that a method does not want <code>null</code> and if you do send <code>null</code> to it anyways, the result will not be pretty. </p> <p>There is a <code>NotNullAttribute</code> and a <code>CanBeNullAttribute</code> in <a href="http://abdullin.com/shared-libraries/" rel="noreferrer">Lokad Shared Libraries</a>, in the <code>Lokad.Quality</code> namespace.</p> <p>But how does that work? I looked at the source-code of those two attributes, and it looks like this:</p> <pre><code>[AttributeUsage(AttributeTargets.Method | AttributeTargets.Parameter | AttributeTargets.Property | AttributeTargets.Delegate | AttributeTargets.Field, AllowMultiple = false, Inherited = true)] [NoCodeCoverage] public sealed class NotNullAttribute : Attribute { } [AttributeUsage(AttributeTargets.Method | AttributeTargets.Parameter | AttributeTargets.Property | AttributeTargets.Delegate | AttributeTargets.Field, AllowMultiple = false, Inherited = true)] [NoCodeCoverage] public sealed class CanBeNullAttribute : Attribute { } </code></pre> <p>Two empty classes inheriting from <code>Attribute</code>. How are they used? Do you have to look up xml-documentation and know that it is there? Cause I tried to both make my own copy of the attribute and to use the Lokad version, but when I tried to send a null directly in, I got no message. Neither from ReSharper nor from VS. Which I kind of expected actually. But how are they used? Can I somehow make VS generate warnings for me if I try to send something that is null in there? Or is it just used in some kind of testing framework? Or?</p>
    singulars
    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. PTQuestion
    1. USDan Neely
    1. USSvish
    plurals
    1. This table or related slice is empty.
    1. PL
      singulars
      1. LTLinked
    2. PL
      singulars
      1. LTLinked
    3. PL
      singulars
      1. LTLinked
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    2. PO
      singulars
      1. PTAnswer
    3. PO
      singulars
      1. PTAnswer
    1. VO
      singulars
      1. POC#: How to Implement and use a NotNull and CanBeNull attribute
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. POC#: How to Implement and use a NotNull and CanBeNull attribute
      1. This table or related slice is empty.
      1. VTUpMod
    3. VO
      singulars
      1. POC#: How to Implement and use a NotNull and CanBeNull attribute
      1. This table or related slice is empty.
      1. VTUpMod
    1. COTo comment on your specific case, those attributes don't do anything and are just "documentation". The other answers give good alternatives, though.
      singulars
      1. POC#: How to Implement and use a NotNull and CanBeNull attribute
      1. USSander
    2. CO`Nullable` is a better name for `CanBeNull`, just saying :)
      singulars
      1. POC#: How to Implement and use a NotNull and CanBeNull attribute
      1. USAhmet Alp Balkan - Google
 

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