[ http://issues.apache.org/jira/browse/OFBIZ-336?page=all ]
Leon Torres updated OFBIZ-336:
------------------------------
Attachment: complex-alias-default-value.patch
Here's an implementation of default-value for complex alias. I removed two
constructor methods in ComplexAliasField that weren't being used, one of which
would cause confusion with the new field.
To use, try something like the following:
<alias entity-alias="OI" name="quantity" function="sum">
<complex-alias operator="-">
<complex-alias-field entity-alias="OI" field="quantity"
default-value="0"/>
<complex-alias-field entity-alias="OI" field="cancelQuantity"
default-value="0"/>
</complex-alias>
</alias>
This should be tested across as many databases as possible.
There is an implementation quirk that absolutely needs review. The coalesce
function is generated as follows:
COALESCE(${fieldName},'${defaultValue}')
Note the single quotations around defaultVaue. In the example, this gets
resolved as COALESCE(OI.QUANTITY,'0'). This actually works on postgresql and
mysql, but I don't know if this will cause issues on other databases. If it
does, then we'll need to detect the field type and set it up accordingly.
> Improve complex-alias to handle nulls and defaults
> --------------------------------------------------
>
> Key: OFBIZ-336
> URL: http://issues.apache.org/jira/browse/OFBIZ-336
> Project: OFBiz (The Open for Business Project)
> Issue Type: Improvement
> Components: framework
> Reporter: Leon Torres
> Priority: Minor
> Attachments: complex-alias-default-value.patch
>
>
> The idea behind complex-alias is useful for certain things, but the way it
> works now is not useful. Suppose you build a simple addition rule. If any
> variable in the equation is null, the entire alias resolves to null.
> For example, suppose you create a view entity to report quantities on
> OrderItem. The query would be:
> select product_id, (quantity - cancel_quantity) from order_item;
> However if you run this, you'll see that where quantity or cancel_quantity
> are null, the result is null. A solution in postgresql is to use the
> coalesce function to specify a default value:
> select product_id, (coalesce(quantity, 0) - coalesce(cancel_quantity, 0))
> from order_item;
> Now the query works.
> So the fix I think is to add another attribute default-value="something". If
> the default-value is present, then add the coalesce function. Not sure
> whether this is standard sql or not.
> I also encountered this issue for concatenation || operator, so I think it
> affects most operations.
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