====Limitations====

There are several features of the GraphQL language that are not fully supported //at this time//. If you find yourself in need of these features, please contact us - we may be able to add them to our development timeline.

===Unsupported Functions===

==Queries Only==

At the current time, GraphQL is only intended for //queries//. Mutations and Subscriptions are not available.

==Fragments==

We currently do not support **Fragments** in GraphQL queries.

==Directives==

Currently, directives such as **@skip** and **@include** are not supported. Note that the system only includes property values if they exist on the asset and does not raise errors if a property you're asking for doesn't exist.

===Differences in Behaviour===

==Typename==

As ARDI assets each have multiple types, the **__typename** metadata property returns a //list// of results rather than a single string. Results are in the natural (ie. ARDI) case, instead of [[camelCase|camelCase]].

==Nested Queries==

If you ask for related assets //without specifying the properties you want to see//, the system will use the properties used in the parent query.

This means that the system will loop over all children, creating a nested query that will continue down through children, grand-children, great grand-children etc.

==Historical Parameter Duplication==

The **range**, **from**, **to** and **sample** variables are copied to all children.

Let's look at this in the following query.

<code>
query MyQuery {
  machine(id: 46,range: "20 minutes") {    
    name    
    temperature
    inside {
      name
      speedActual
    }
  }
}
</code>

This searches for the **machine** with the ID number '46'. It reads the temperature, then finds all of the assets //inside// it. 

For each of those //child// assets, it reads the name and actual speed.

Processing this in the traditional way, you'll have history for the //temperature//, but none for the //speed//, because you haven't specified a range on 'inside'.

But because we copy these properties from parent to child (unless they're specifically overridden), //all// of the points will have history, since it's implied that the 'inside' assets have the same range and number of samples as the parent.