refactor(IsNew): check string type PrimaryKey first #538

[ArgoZhang]

#Issue
link #538

[pleb]

Hey @ArgoZhang why was this causing an issue? I don't see how this change affects anything.

[ArgoZhang]

Hey @ArgoZhang why was this causing an issue? I don't see how this change affects anything.

[TableName("Groups")]
public class Group
{
    public string Id { get; set; }
    public string GroupName { get; set; }

    public void Save(Group poco)
    {
        var db = DbManager.Create();
        db.Save(new Group() { Id = "", GroupName = "UnitTest" });
    }
}

because Id value is String.Empty not null, so IsNew method work incorrectly.
the IsNew method will always run false when PrimaryKey is string type and value is "". so run into Update method.
i think that this is a bug. and you?
by the way it works when value is NULL

[pleb]

@ArgoZhang could you please fix the line endings?

[ArgoZhang]

@pleb done! resolved the conflicts.
thank you for pick up this PR.
😃