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POHow to delete a child from a bidirectional many-to-many association?
 

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  1. POHow to delete a child from a bidirectional many-to-many association?
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    <p>How can I delete a child from a bidirectional <strong>many-to-many association</strong>?</p> <p>Deleting the child does not work because I get an exception (FK Violation).</p> <p>Just removing the child from the parent and call saveorupdate on the parent does not do anything.</p> <p>Entities:</p> <pre><code>public class Employee : Entity { public virtual string LastName { get; set; } public virtual string FirstName { get; set; } public virtual string EMail { get; set; } public virtual IList&lt;LoanedItem&gt; LoanedItems { get; set; } public virtual ISet&lt;Team&gt; Teams { get; set; } public Employee() { if (LoanedItems == null) { LoanedItems = new List&lt;LoanedItem&gt;(); } if (Teams == null) { Teams = new HashedSet&lt;Team&gt;(); } } public virtual void AddTeam(Team team) { Teams.Add(team); team.Employees.Add(this); } public virtual void RemoveTeamFromEmployee(Team team) { Teams.Remove(team); } } public class Team : Entity { public virtual string Name { get; set; } public virtual ISet&lt;Employee&gt; Employees { get; set; } public Team() { if (Employees == null) { Employees = new HashedSet&lt;Employee&gt;(); } } public virtual void RemoveEmployeeFromTeam (Employee employee) { var result = Employees.Remove(employee); } public virtual void AddEmployee(Employee employee) { Employees.Add(employee); employee.Teams.Add(this); } } </code></pre> <p>Mappings:</p> <pre><code>public class TeamMap : ClassMap&lt;Team&gt; { public TeamMap() { // identity mapping Id(p =&gt; p.Id) .Column("TeamId") .GeneratedBy.Identity(); // column mapping Map(p =&gt; p.Name); // Employee is responible for the relationship HasManyToMany(p =&gt; p.Employees) .Table("TeamEmployee") .AsSet() .LazyLoad() .Inverse() .Cascade.SaveUpdate() .ParentKeyColumn("TeamId") .ChildKeyColumn("EmployeeId") .NotFound.Ignore(); } } public class EmployeeMap : ClassMap&lt;Employee&gt; { public EmployeeMap() { // identifier mapping Id(p =&gt; p.Id) .Column("EmployeeId") .GeneratedBy.Identity(); // column mapping Map(p =&gt; p.EMail); Map(p =&gt; p.LastName); Map(p =&gt; p.FirstName); // Employee is responible for the relationship HasManyToMany(p =&gt; p.Teams) .Table("TeamEmployee") .AsSet() .LazyLoad() .ParentKeyColumn("EmployeeId") .ChildKeyColumn("TeamId") .Cascade.SaveUpdate() .NotFound.Ignore(); HasMany(p =&gt; p.LoanedItems) .Cascade.SaveUpdate() .KeyColumn("EmployeeId"); } } </code></pre> <p><strong>EDIT</strong></p> <p>Code to delete a team:</p> <pre><code>//Test Case 2 //Delete Team 2 Team team = session.Get&lt;Team&gt;(2); List&lt;Employee&gt; employees = team.Employees.ToList(); foreach (var employee in employees) { team.RemoveEmployeeFromTeam(employee); } session.Delete(team); </code></pre>
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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.

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