c# - How to update binding based on value being dirty? -

i've datagrid 5 columns. first 3 columns part of parent object , last 2 columns part of child object. i've username column 6th column.

when update first 3 columns of parent object, username reflects correctly. when update last 2 columns of child object, doesn't update username.

i've tried binding , doing logic in child object , before 'save' username updates correctly last 2 columns after save reverts previous username.

my question is, how keep updated username after save?

xaml:

<datagridtextcolumn header="updated by" isreadonly="true" binding="{binding childobject.updateduser, updatesourcetrigger=propertychanged}"/> 

child object:

public string updateduser {         {         var parent = this.crawlparentfindtype<parentobject>();          if (column4isdirtybyvalue || column5isdirtybyvalue)             return updatedbyusername;          else return parent.updatedbyusername;     } }  public bool column4isdirtybyvalue { { return fieldmanager.isfielddirty(column4property); } } public bool column5isdirtybyvalue{ { return fieldmanager.isfielddirty(column5property); } }   public string column4 {     { return getproperty(column4property); }     set { setproperty(column4property, value);  onpropertychanged(x => x.updateduser); } }  public string column5 {     { return getproperty(column5property); }     set { setproperty(column5property, value); onpropertychanged(x => x.updateduser); } } 

why code complex? think reason in onpropertychanged(x => x.updateduser); call updateduser property changed, property doesn't have setter. code below should work you, imho:

private bool _updateduser; public bool updateduser {     { return _updateduser; }     set { this.setproperty(ref this._updateduser, value); } }  private string _column5; public string column5 {     { return _column5; }     set     {         this.setproperty(ref this._column5, value);          updatedusercheck();     } }  private void updatedusercheck() {     this.updateduser = // check here } 

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