public override int Update <T>(T entity)
{
Utils.CheckNull(entity);
TypeDescriptor typeDescriptor = TypeDescriptor.GetDescriptor(entity.GetType());
EnsureMappingTypeHasPrimaryKey(typeDescriptor);
object keyVal = null;
MappingMemberDescriptor keyMemberDescriptor = typeDescriptor.PrimaryKey;
MemberInfo keyMember = keyMemberDescriptor.MemberInfo;
IEntityState entityState = this.TryGetTrackedEntityState(entity);
Dictionary <MappingMemberDescriptor, DbExpression> updateColumns = new Dictionary <MappingMemberDescriptor, DbExpression>();
foreach (var kv in typeDescriptor.MappingMemberDescriptors)
{
var member = kv.Key;
var memberDescriptor = kv.Value;
if (member == keyMember)
{
keyVal = memberDescriptor.GetValue(entity);
keyMemberDescriptor = memberDescriptor;
continue;
}
AutoIncrementAttribute attr = (AutoIncrementAttribute)memberDescriptor.GetCustomAttribute(typeof(AutoIncrementAttribute));
if (attr != null)
{
continue;
}
var val = memberDescriptor.GetValue(entity);
if (entityState != null && !entityState.IsChanged(member, val))
{
continue;
}
DbExpression valExp = DbExpression.Parameter(val, memberDescriptor.MemberInfoType);
updateColumns.Add(memberDescriptor, valExp);
}
if (keyVal == null)
{
throw new Exception(string.Format("实体主键 {0} 值为 null", keyMember.Name));
}
if (updateColumns.Count == 0)
{
return(0);
}
DbExpression left = new DbColumnAccessExpression(typeDescriptor.Table, keyMemberDescriptor.Column);
DbExpression right = DbExpression.Parameter(keyVal, keyMemberDescriptor.MemberInfoType);
DbExpression conditionExp = new DbEqualExpression(left, right);
DbUpdateExpression e = new DbUpdateExpression(typeDescriptor.Table, conditionExp);
foreach (var item in updateColumns)
{
e.UpdateColumns.Add(item.Key.Column, item.Value);
}
int ret = this.ExecuteSqlCommand(e);
if (entityState != null)
{
entityState.Refresh();
}
return(ret);
}