Databases
StackOverflow2013
Postsdbo
POCorrect way to reordering items in a list (nhibernate)
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POCorrect way to reordering items in a list (nhibernate)
    primarykey
    data
    text
    <p>What is the correct way to reorder a list when using NHibernate?</p> <p>This is my list:</p> <pre><code> private IList&lt;MediaItem&gt; media = new List&lt;MediaItem&gt;(); public virtual IList&lt;MediaItem&gt; Media { get { return media.ToReadOnlyCollection(); } } </code></pre> <p>And I'm reordering by passing an ordered list of <code>MediaItem</code> ids (<code>Guid</code>):</p> <pre><code> public virtual void UpdateMediaOrder(IList&lt;Guid&gt; mediaIds) { // TODO remove any unmatched items foreach (var mi in Media) { int index = mediaIds.IndexOf(mi.Id); if (index == -1) index = media.Count() -1; media[index] = mi; } } </code></pre> <p>When I reorder the list (in this case a list containing 3 items), NHibernate executes the following:</p> <pre><code>NHibernate: DELETE FROM PortfolioProjectMedia... NHibernate: INSERT INTO PortfolioProjectMedia... NHibernate: INSERT INTO PortfolioProjectMedia... NHibernate: INSERT INTO PortfolioProjectMedia... </code></pre> <p>I guess I expected to see <code>Updates</code> rather than clearing the list. </p> <p>Am I doing something wrong, or is this the intended behaviour?</p> <h3>Update</h3> <p>In case it wasn't already clear, I need to map my list as a NHibernate List (not a Set or a Bag) so that the index of the items is persisted.</p> <p>Here's the mapping of the <code>MediaItem</code> collection on <code>Project</code>. <code>MediaItem</code> has no reference to projects. The relationship is many-to-many.</p> <pre><code> HasManyToMany(p =&gt; p.Media) .Table("PortfolioProjectMedia") .Access.CamelCaseField() .ParentKeyColumn("ProjectId") .ChildKeyColumn("MediaItemId") .Cascade.SaveUpdate() .AsList(i =&gt; i.Column("ListIndex").Type&lt;int&gt;()); </code></pre>
    singulars
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PTQuestion
    1. USBen Foster
    1. USBen Foster
    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. PO
      singulars
      1. PTAnswer
    1. VO
      singulars
      1. POCorrect way to reordering items in a list (nhibernate)
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. POCorrect way to reordering items in a list (nhibernate)
      1. This table or related slice is empty.
      1. VTUpMod
    1. COCan you show the hbm config file of MediaItem and its parent
      singulars
      1. POCorrect way to reordering items in a list (nhibernate)
      1. USShuhel Ahmed
 

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