When we changed to pass an interface (Data changed to a List instead of List), properties in sub interfaces could not be found so we decided to try and pass it as Json with JsonDataSource but then we get the error:
System.InvalidOperationException: Tag 'if' is not well-formed. A conditional expression should return a Boolean value.
When the data source is a POCO the expression is compiled against the actual .NET type (bool Disabled). The C# unary operator ! is therefore understood and the template works.
JsonDataSource does not deserialize the JSON into a POCO; it creates a dynamic object (JObject/JToken). The expression engine used by Assembly evaluates the condition on those dynamic values. The unary ! operator is not supported for a JToken/dynamic value, so the parser throws
System.InvalidOperationException: Tag 'if' is not well‑formed. A conditional expression should return a Boolean value.
Hence you must use an explicit Boolean comparison (s.Disabled == false or s.Disabled != true).
How to make it work reliably
Ensure the JSON field is a proper JSON boolean ("Disabled": true / "Disabled": false).
If you need the ! syntax, convert the JSON to a POCO before passing it to the template, e.g.:
var list = JsonConvert.DeserializeObject<List<MyImplementation>>(json);
editor.DataSource = new JsonDataSource(list);
(or use ObjectDataSource with the POCO list).
Upgrade – the latest GroupDocs.Assembly release contains a small fix that improves handling of boolean values in JsonDataSource. If you can, move to the newest version and retest.
What we need to verify
A minimal JSON sample that reproduces the error (show the Disabled field).
The interface definition (IMyInterface) you are using with JsonDataSource.
The exact stack trace (if any) beyond the “Tag ‘if’ is not well‑formed” message.
Providing those details will let us confirm whether the issue is purely the expression‑parser limitation or if there is an underlying bug that needs to be logged.
Hi Yuriy, thank you for your reply!
I have reverted back to not use json anymore, but go for the POCO approach, I don’t think that it’s a bug but rather a bad implementation, that it should not be dependent on what source I’m using if I could use !s.Disabled vs s.Disabled == false.
Can you please explain why hiearchy is not working when I’m using interfaces, for example:
public interface IBlock : IBlockDisabled
{
string Name { get; set; }
}
If i pass in a List I can use the property “Name” but not “Disabled” but if I do
public interface IBlock : IBlockDisabled
{
string Name {get;set;}
new bool Disabled { get; set; }
}
I can use both. I would be nice to be able to use the whole interface.
At some point I tested with the latest version, but I couldn’t see any improvements.