FetchXML link entity including null values - dynamics-crm

Question

I'm trying to query CRM using FetchXML. Here is the query to account entity, this returns me 10 records, here new_primaryactivityname field has NULL for few records.
<fetch mapping="logical" version="1.0">
<entity name="account">
<attribute name="accountid" />
<attribute name="name" />
<attribute name="new_primaryactivity" />
</entity>
</fetch>
Now i want to link it with another entity to get a new field, i want to do LEFT OUTER JOIN like in sql, to keep the NULL values while linking, so i provided link type as outer and i applied a filter for few conditions.
<fetch mapping="logical" version="1.0">
<entity name="account">
<attribute name="accountid" />
<attribute name="name" />
<attribute name="new_primaryactivity" />
<link-entity name="stringmap" from="attributevalue" to="new_primaryactivity" alias="new_primaryactivity_lookup_name" link-type="outer">
<attribute name="value" />
</link-entity>
<filter type="and">
<condition entityname="new_primaryactivity_lookup_name" attribute="attributename" operator="eq" value="new_primaryactivity" />
<condition entityname="new_primaryactivity_lookup_name" attribute="objecttypecode" operator="eq" value="999" />
</filter>
</entity>
</fetch>
The result(less than 10 records) ignores the records with new_primaryactivityname as NULL, what am i missing in FetchXML query?
I do not have much access to to system other than use FetchXML, i referred few suggestions to use tool in help building FetchXML query but i can't do it due to restrictions.

Answer 1

I think it's the location of your filter block.
The way it is written now, you're linking account and stringmap together with the outer-join, and then you're applying the filter to the results.
I think you need to do the filter inside the outer-join like so:
<fetch mapping="logical" version="1.0">
<entity name="account">
<attribute name="accountid" />
<attribute name="name" />
<attribute name="new_primaryactivity" />
<link-entity name="stringmap" from="attributevalue" to="new_primaryactivity" alias="new_primaryactivity_lookup_name" link-type="outer">
<attribute name="value" />
<filter type="and">
<condition attribute="attributename" operator="eq" value="new_primaryactivity" />
<condition attribute="objecttypecode" operator="eq" value="999" />
</filter>
</link-entity>
</entity>
</fetch>
Alternatively you could try to write the filter differently and explicitly allow for the null values
<fetch mapping="logical" version="1.0">
<entity name="account">
<attribute name="accountid" />
<attribute name="name" />
<attribute name="new_primaryactivity" />
<link-entity name="stringmap" from="attributevalue" to="new_primaryactivity" alias="new_primaryactivity_lookup_name" link-type="outer">
<attribute name="value" />
</link-entity>
<filter type="or">
<condition entityname="new_primaryactivity_lookup_name" attribute="attributename" operator="eq" value="" />
<filter type="and">
<condition entityname="new_primaryactivity_lookup_name" attribute="attributename" operator="eq" value="new_primaryactivity" />
<condition entityname="new_primaryactivity_lookup_name" attribute="objecttypecode" operator="eq" value="999" />
</filter>
</filter>
</entity>
</fetch>
I haven't tested either of these, but hopefully one of these works for you