/// <summary>
/// 检查指定的值对于当前的验证特性是否有效。
/// </summary>
/// <param name="value">属性值。</param>
/// <param name="validationContext">验证上下文对象。</param>
/// <returns></returns>
protected override ValidationResult IsValid(object value, ValidationContext validationContext)
{
Guard.ArgumentNull(validationContext, "validationContext");
var entityType = validationContext.ObjectType;
if (ValidateNullable(value) == ValidationResult.Success)
{
return(ValidationResult.Success);
}
IDatabase database;
try
{
database = DatabaseFactory.GetDatabaseFromScope();
}
catch (UnableGetDatabaseScopeException exp)
{
return(new ValidationResult(exp.Message));
}
var paramaters = new ParameterCollection();
var entity = validationContext.ObjectInstance as IEntity;
var syntax = database.Provider.GetService <ISyntaxProvider>();
var eqb = new EntityQueryBuilder(syntax, null, entityType, paramaters);
eqb = eqb.Select().Count().From().Where(Property, value);
if (entity.EntityState != EntityState.Attached)
{
foreach (var pk in PropertyUnity.GetPrimaryProperties(entityType))
{
eqb = eqb.And(pk, entity.GetValue(pk.Name), QueryOperator.UnEquals);
}
}
var result = database.ExecuteScalar <int>(eqb.ToSqlCommand(), paramaters);
return(result == 0 ? ValidationResult.Success : new ValidationResult(FormatErrorMessage(validationContext.DisplayName)));
}
