EntityEngine: Conditional view-links in a view-entity

[David Gay]

Hi, all!  I've been looking into using view-entity entries to (in this
instance) collect product information, and have some questions about
"static conditionals".  But first, some context for discussion
purposes.  ;-)

Let's say I'd like to have a Product view that includes the product's
SKU as a column.  Here's a sample entitydef.xml (angle-brackets
converted to square-brackets):

[view-entity entity-name="ProductFindViewEntity"
package-name="com.emforium.inventory" title="Product-Find View
Entity"]
    [member-entity entity-alias="PR" entity-name="Product" /]
    [member-entity entity-alias="SKU" entity-name="GoodIdentification" /]
    [alias entity-alias="PR" name="productId" /]
    [alias entity-alias="SKU" name="sku" field="idValue" /]
    [alias entity-alias="SKU" name="skuTypeId"
field="goodIdentificationTypeId" /]
    [view-link entity-alias="PR" rel-entity-alias="SKU" rel-optional="true"]
        [key-map field-name="productId" /]
    [/view-link]
[/view-entity]

Let's say I've also added two GoodIdentification rows for a product:

[GoodIdentification productId="ENCHILADAS"
goodIdentificationTypeId="SKU" idValue="ENCH-SKU" /]
[GoodIdentification productId="ENCHILADAS"
goodIdentificationTypeId="MANUFACTURER_ID_NO" idValue="123-ENCH-456"
/]

Now, a query for productId="ENCHILADAS" on this entity will yield two rows:

productId="ENCHILADAS", sku="ENCH-SKU", skuTypeId="SKU"
productId="ENCHILADAS", sku="123-ENCH-456", skuTypeId="MANUFACTURER_ID_NO"

Obviously, I need a conditional (e.g. skuTypeId="SKU" OR
skuTypeId=NULL), which I can do easily enough each place I do the
query, but I'd prefer to add that to the entitydef.xml file, since
it's the same in all cases (and avoids messy null-logic, etcetera).
Perhaps something like this:

    ...
    [view-link entity-alias="PR" rel-entity-alias="SKU" rel-optional="true"]
        [key-map field-name="productId" /]
        [where entity-alias="SKU" field="goodIdentificationTypeId"
value="SKU" /]
    [/view-link]
    ...

So, my questions: Have I missed some already-available functionality?
Is there a best-practice for this situation?  Has anyone else
encountered this issue, and if so, how did you solve it?  Are there
arguments against this sort of extension?

Thanks in advance,
.Dave