Calling a method on one of a view’s data sources

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I have a small dilemma

I've created a view OnHandInquiryView (based on query OnHandInquiryQuery)

This view is going to be used as a datasource on a read-only inquiry form, and possibly on a report.

When I look at my view’s Metadata --> Datasources, nothing shows up, but they do show up under the Metadata --> OnHandInquiryQuery

The query contains InventTable as a datasource

I have a number of custom display and calculation method on InventTable

One method is called findPackSize, which does all sorts of wonderful things looking at fields on InventTable, unit conversion tables, and other custom tables.

I would like to add a display method on my OnHandInquiryView which will call the InventTable’s findPackSize method

How can I reference a view’s datasource (or the datasource in the query that is used to build the view) within a method on that view?

I’ve tried using InventTable, and InventTable_ds, but the method on my view doesn’t like either of those.

Rewriting the methods from InventTable onto my OnHandInquiryView is not really desirable, because it would be time consuming, would require me to maintain similar code in two separate methods, and might not work anyway, since I would still need to reference fields from InventTable in my view-level method

This is just one example. There are many other methods, on this and other data sources of my view, which I would like to be able to call from a method on my view

If anyone has ever done something like this (calling a method on one of a view’s data sources, and/or referencing a field that is not one of the field on the view but is a field in one of the datasources), please let me know.

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Brandon Wiese 17,788 on at

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It is not possible in a view to access methods of underlying data sources. The reasoning is simple. Views in the AOT become SQL Server views directly in the database, and SQL Server cannot run X++. Having said that, it is possible to build some quite powerful logic directly onto those views in the form of computed columns. There are good examples of this in the AOT. Check out the views InventTransGrouped, InventTableExpanded, InventSumAggrDeltaView, etc. There you can see complex usage of the SysComputedColumn class to build calculated fields into SQL Server views.

It sounds from your description like you probably won't be able to accomplish what your method does using calculated fields.

There's no reason to be stuck using a view in your case and suffer not being able to use your display methods. Instead, build a query, which can itself be assigned to the data source of a form, and then allows you to reference the display methods of underlying data sources directly. And then you can build a view on that query, and use that view in cases where you do not need the display methods.

Hope this helps.

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Martin Dráb 237,803 Most Valuable Professional on at

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I have one more suggestion. You clearly can't used InventTable.findPackSize() directly, but you can add a new display method to your view and call the same logic that is used by findPackSize().

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Community Member on at

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That's pretty much what I wound up doing.

In this case, I was trying to call a custom method on InventTable, and my view contains the ItemId.

My solution was to write a method on my view which declared an InventTable object. Using the ItemId from my view, I did a find on InventTable, and called the method on InventTable that way. Probably not the most efficient solution, but it works.

Bill

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Martin Dráb 237,803 Most Valuable Professional on at

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If you make a database request in your display method, it's quite expensive, therefore you'll get much better performance if you can avoid it. It suggests that your view doesn't contain all necessary fields, therefore consider adding them.

If you want to have the extra query anyway, make sure that you at least cache the display method.

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