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Fields() function and deep object graphs

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IT asked on 27 Feb 2012, 04:17 AM

I'm trying to use the Fields() function in the Groupings property of a report.

It will work if I use a field that is at the base of my object graph. For example:-

=Fields("Price")

However if I try to use a field from deeper in the graph, the generated report is blank. For example:-

=Fields("Supplier.Name")

Both of the above fields work fine as bound fields in the report itself.

Specifying the field directly in the Groupings parameter works as expected:-

=Fields.Supplier.Name

The reason I want to use the Fields function is that I am passing a parameter into the report so I can change the grouping from the page from which the report is run.

Can anyone tell me if the Fields() method should work with deep mapped fields? or was this overlooked when deep object support was added in Q2 2007?

Thanks in advance.

7 Answers, 1 is accepted

answered on 29 Feb 2012, 11:25 PM

Elian,

Thanks for your reply, however it doesn’t really answer my question.

I was aware the Fields() function returns an object… that’s what I’m counting on. But it’s not what it returns that is the problem, it’s where it looks.

As far as the engine looking for an object with the name “Supplier.Name”… that’s precisely what I want. Supplier.Name is an object (in this case a string property on my Supplier object), which it appears the Fields() function is unable to resolve because it’s more than one level deep on the data record's object graph.

So to my original question: prior to Q2 2007, specifying fields like =Fields.Supplier.Name didn’t work, because the engine could not evaluate a deep object graph on the data record. In Q2 2007 support for this was added to the Fields object, but not (it appears) to the Fields() function.

If the Fields() function does work exactly the same way as the Fields object, then how do I achieve what I want as above? I want to pass the field itself to the Sorting (or Grouping) parameter by specifying a property on my data record via a string I pass in via a parameter.

It appears the Fields() function was designed specifically for this purpose… to allow me to obtain a reference to a field (and not the value of the field) using a string representation of that field's name, so that I can pass that reference to some other function in the report.

In your example:

=Fields(“Supplier”).Name

I can pass the “Supplier” as a parameter, but I cannot pass “Name”, so it would only work if I wanted to constrain my sorting to the Name property of the desired object (which won’t work).

Perhaps I could call =Fields(“Supplier”).Fields(“Name”), however even if that did work (I haven’t tried) it wouldn’t solve the problem… I’m then restricted to grouping/sorting by properties that are exactly 2 levels deep in graph (this won’t work either)

So for an example, if my object looks like this:-

Order (the data source is a list of these)

Id (int)

Reference (string)

Customer (customer object)

Name (string)

Country (string)

Supplier (supplier object)

Name (string)

Country (string)

How could I build a report with the ability to dynamically sort by one of these three fields:-

Reference
Supplier.Name
Customer.Country

answered on 03 Sep 2012, 10:16 PM

Man... I am adding my vote to get this to work ASAP!

I just can't believe Telerik can't get the Fields() function to accomodate this.
I mean... this is practically the same concept that we use on RadGrids when we declaritively assign a data field to a column. If we want the field 3 layers up or down the chain, we just use "object1.object2.FieldName". Somehow RadGrid knows what that "text" representation of a object/field combination should be. I have to assume behind the scenes it is taking that "text" and figuring out the actual object/field from it...no matter how many layers it is.

It takes the Fields() function from a great idea to practically useless (unless you are creating reports with only flat objects). Telerik has a wonderful ORM. Whether I choose to use the OpenAccessDataSource directly or use an ObjectDataSource against some ORM objects, there ARE going to be layers. The minute I have any layers, the Fields() function pretty much can't ever be used, because at some point the needs of the report will be such that fields from the reference objects are needed and the Fields() function will blow up. So, you are stuck designing a solution that can accomodate all fields (which means Fields() can't be used).

Simple example...
Since Telerik can't yet support any type of auto/user sorting on fields (or some out of the box mechinism for the user to chose which field(s) to sort by), I was coming up with my own solution based on this concept. I wasn't doing it exactly like that, but similar principles. I was creating my own function that returned the sorting values for a datasource used in a "sortby" parameter. Those "values" were the "field names" that you would use if you wanted to sort the report normally. So, in my sorting setup, I used something like:
= Fields(Parameters.SortBy.Value)
This works great!!!
As long as my datasource pulls the "field names" (presented in a dropdown), that one sorting expression can accomodate an unlimited # of user sorts.
However, this ONLY WORKS for the TOP level of fields!!
If you reference ANY sub object, the Fields() function blows up.
So, my one nice expression that should be able to handle anything is now useless.
Instead???
I have to list out 20 expressions...one for each possible sort... testing the "text/value" and assigning the field myself.
Such a PITA!!
So much so.... that I just say screw it.
Totally not worth the effort when all this could be avoided if the Fields() function just did what it is supposed to do.

If we aren't going to have out-of-box user/sortable functonality, can we PLEASE at least get the Fields() function working?
Pretty sure Telerik could just copy/paste the code for how RadGrid or any of the other bindable objects handle it when a layered object is referenced as text.