Entity Framework Tutorial Basics (+): Validate entity

Validate Entity

You can write the custom server side validation for any entity. To accomplish this, override validateentity method of DBContext as shown below.

protected OverrideSystem.Data.Entity.Validation.DbEntityValidationResult validateentity (Dbentityentry entityentry, system.collections.generic.idictionary<Object,Object>items) {    if(entityentry.entity isStudent) {        if(entityentry.currentvalues.getvalue<string> ("Studentname") =="")        {            varList =NewList<system.data.entity.validation.dbvalidationerror>(); List. ADD (NewSystem.Data.Entity.Validation.DbValidationError ("Studentname","Studentname is required")); return NewSystem.Data.Entity.Validation.DbEntityValidationResult (entityentry, list); }    }    return Base. Validateentity (entityentry, items);}

As can see in the above code, we is validating the Student entity. If Studentname is blank, then we were adding dbvalidationerror into Dbentityvalidationresult. So whenever the Dbcontext.savechanges method and you try to save Student entity without studentname, then it'll thr ow dbentityvalidationexception. For example:

Try{    using(varCTX =Newschooldbentities ()) {ctx. Students.add (NewStudent () {studentname ="" }); CTx. Standards.add (NewStandard () {StandardName ="" }); CTx.    SaveChanges (); }}Catch(dbentityvalidationexception dbex) {foreach(Dbentityvalidationresult Entityerrinchdbex.entityvalidationerrors) {foreach(Dbvalidationerror Errorinchentityerr.validationerrors) {Console.WriteLine ("Error property Name {0}: Error Message: {1}", error. PropertyName, error.        ErrorMessage); }    }}

Entity Framework Tutorial Basics (+): Validate entity