c# - Wpf DatagridComboBoxColumn binding for two tables? -

i have classes books , publishing houses:

public partial class books {     public books()     {         this.authors = new observablecollection<authors>();     }      public int bid { get; set; }     public string title { get; set; }     public int phid { get; set; }     public nullable<short> pubyear { get; set; }     public nullable<short> edition { get; set; }      public virtual publishinghouse publishinghouse { get; set; }     public virtual observablecollection<authors> authors { get; set; } } public partial class publishinghouse {     public publishinghouse()     {         this.books = new observablecollection<books>();     }      public int phid { get; set; }     public string title { get; set; }     public string city { get; set; }          public virtual observablecollection<books> books { get; set; } } 

so have datagrid shows me of books:

<window.resources>     <collectionviewsource x:key="booksviewsource" d:designsource="{d:designinstance {x:type local:books}, createlist=true}"/>     <collectionviewsource x:key="booksauthorsviewsource" source="{binding authors, source={staticresource booksviewsource}}"/>     <collectionviewsource x:key="authorsviewsource" d:designsource="{d:designinstance {x:type local:authors}, createlist=true}"/>     <collectionviewsource x:key="publishinghouseviewsource" d:designsource="{d:designinstance {x:type local:publishinghouse}, createlist=true}"/> </window.resources> <grid datacontext="{staticresource booksviewsource}" margin="0,0,2,0">     <datagrid itemssource="{binding}">         <datagrid.columns>             <datagridtextcolumn header="b id" binding="{binding bid}"/>             <datagridtextcolumn header="title" binding="{binding title}"/>             <datagridtextcolumn header="#" binding="{binding edition}"/>             <datagridtextcolumn header="year" binding="{binding pubyear}"/>             <datagridcomboboxcolumn x:name="phidcomboboxcolumn" selecteditembinding="{binding phid}" />         </datagrid.columns>     </datagrid> 

the thing want, set default value of phidcomboboxcolumn taken book, when want edit it, want see list of phid's of avaliable publishinghouses. must somehow bind 'datagridcomboboxcolumn' 2 datasources?

your book class should have property containing list of phid's of avaliable publishinghouses this:

public observablecollection<int> phidlist {get; set;} 

then datagridcomboboxcolumn changes this:

<datagridcomboboxcolumn header="phids" selecteditembinding="{binding phid}">     <datagridcomboboxcolumn.elementstyle>         <style targettype="combobox">             <setter property="itemssource" value="{binding phidlist}"/>             <setter property="isreadonly" value="true"/>         </style>     </datagridcomboboxcolumn.elementstyle>     <datagridcomboboxcolumn.editingelementstyle>         <style targettype="combobox">             <setter property="itemssource" value="{binding phidlist}"/>         </style>     </datagridcomboboxcolumn.editingelementstyle> </datagridcomboboxcolumn> 

edit

if so, every object of book contain identical collections of avaliable publishinghouses. that's unefficient memory. other solution?

to prevent data redundancy can define phidlist in parent class (e.g. book-list container view-model if you're using mvvm) , combobox data this:

            <datagridcomboboxcolumn                  selecteditembinding="{binding phid}" displaymemberpath="" >                 <datagridcomboboxcolumn.elementstyle>                     <style targettype="{x:type combobox}">                         <setter property="itemssource" value="{binding path=datacontext.bookscontainervm.phidlist, relativesource={relativesource ancestortype={x:type window}}}" />                     </style>                 </datagridcomboboxcolumn.elementstyle>                 <datagridcomboboxcolumn.editingelementstyle>                     <style targettype="{x:type combobox}">                         <setter property="itemssource" value="{binding path=datacontext.bookscontainervm.phidlist, relativesource={relativesource ancestortype={x:type window}}}" />                     </style>                 </datagridcomboboxcolumn.editingelementstyle>             </datagridcomboboxcolumn>