Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>@Eranga is right that this is done by <code>ON DELETE CASCADE</code> setting on relation in the database BUT you are using code first approach and EF creates database for you so the problem here is that your model is not correctly defined because EF didn't create cascading rule for you.</p> <p>Why? Because of this:</p> <pre><code>public class Direction { public int DirectionId { get; set; } public string Abbreviation { get; set; } public virtual Forecast Forecast { get; set; } public virtual List&lt;Transport&gt; Transports { get; set; } } </code></pre> <p><code>Abbreviation</code> is FK property and it is nullable! So EF looks at your model and it sees that you defined <code>Direction</code> entity which can have <code>Abbreviation</code> set to null and because of that it can exists orphaned. Change it to:</p> <pre><code>public class Direction { public int DirectionId { get; set; } [Required] public string Abbreviation { get; set; } public virtual Forecast Forecast { get; set; } public virtual List&lt;Transport&gt; Transports { get; set; } } </code></pre> <p>and removing <code>Forecast</code> will delete all related <code>Direction</code> instances and <code>Transport</code> instances. <code>Stop</code> is different story because it is parent entity to <code>Forecast</code> so it will never be removed with <code>Forecast</code>.</p> <p>Edit:</p> <p>One more point - you don't want to add <code>ON DELETE CASCADE</code> to your relations manually because EF have to know about enabled cascade deletes. EF use this information in case where you have related entities loaded.</p> <p>If you place the rule manually into the database you must use fluent mapping and tell EF about this rule as well. Once you force cascade delete in fluent api you don't need to make it manually in the database - it will be created automatically during database recreation.</p>
    singulars
    1. This table or related slice is empty.
    1. PODeletion of entire entity graph, including relationships, using EF Code First
      singulars
      1. PTQuestion
    1. PTAnswer
    1. USLadislav Mrnka
    1. USLadislav Mrnka
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PODeletion of entire entity graph, including relationships, using EF Code First
      singulars
      1. PTQuestion
    1. This table or related slice is empty.
    1. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    3. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    1. COLadislav, you're great - that was the required piece. The FK relationship is properly created with the ON DELETE CASCADE requirement now. However, I still find I have to do the following in order for the old Direction and Transport items to be deleted: Remove the old Forecast, call SaveChanges() on the context, add the new entity, and call SaveChanges() again. I'm not sure why I should have to do this.
      singulars
      1. PO
      1. USPatrick Sears
    2. COThanks @ladislav-mrnka I figured out I don't need to call SaveChanges() twice - rather, in order for the delete to actually delete the children, I have to load the child entities via Load or by accessing at least one child item in the collection. Again I seem to be missing something simple.
      singulars
      1. PO
      1. USPatrick Sears
 

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