BIML PropertyName for "Direct Input"/SqlCommand of Lookup Task - ssis

Question

<Dataflow Name="Load Tables">
<Expressions>
<Expression PropertyName="[Lookup].[SqlCommand]">"SELECT * FROM " + #[$User::DBSchema] + ".Table1" </Expression>
</Expressions>
[...]
In reference to:
<Lookup Name="Lookup1" CacheMode="Partial" NoMatchBehavior="RedirectRowsToNoMatchOutput" OleDbConnectionName="abc123">
This is part of a much larger package, but when I try to generate it, it gives me an error:
"Could not resolve reference to '[Lookup1].[SqlCommand]' in property 'Property'. '' is invalid. Provide valid scoped name."
In the .dtsx, the needed Property is called "[Lookup1].[SqlCommand]" (and given the same Expression); when changed in the .dtsx file manually the works as expected but I am at a loss of how to translate this into the biml, specifically what reference name to use so it knows where to put the expression.
My question is what is the property name to reference the DirectInput/SqlCommand of the Lookup task? I cannot seem to figure it out.
Here is a picture of how it looks in the dtsx when I change it manually:
Note:
I can't put the expression into the Lookup Task directly because the parameters are dynamically passed into the expression e.g.
<Lookup Name="Lookup1" CacheMode="Partial" NoMatchBehavior="RedirectRowsToNoMatchOutput">
<DirectInput>
SELECT * [etc.]
</DirectInput>

Answer 1

I think what you're missing is when you define your Lookup in the data flow, provide a valid query against a default schema. That will allow the engine to derive the properties of the reference table/set and then once the package is emitted the data flow overrides should take over.
<Dataflow Name="Data Flow Task">
<Expressions>
<Expression ExternalProperty="[Lookup].[SqlCommand]">"SELECT *
FROM
(
VALUES (1, 'b')
,(100, 'a')
,(11, 'c')
) D(colRef, colVal)"</Expression>
</Expressions>
<Transformations>
<OleDbSource Name="OLE DB Source" ConnectionName="SourceConnectionOLEDB">
<DirectInput>SELECT 100 aS col
union all select 11</DirectInput>
</OleDbSource>
<Lookup Name="Lookup" OleDbConnectionName="SourceConnectionOLEDB">
<Outputs>
<Column SourceColumn="colVal" TargetColumn="colVal" />
</Outputs>
<Parameters>
<Parameter SourceColumn="col" />
</Parameters>
<Inputs>
<Column SourceColumn="col" TargetColumn="colRef" />
</Inputs>
<DirectInput>SELECT *
FROM
(
VALUES (1, 'b')
,(100, 'a')
) D(colRef, colVal)</DirectInput>
<ParameterizedQuery>select * from (SELECT *
FROM
(
VALUES (1, 'b')
,(100, 'a')
) D(colRef, colVal)) [refTable]
where [refTable].[colRef] = ?</ParameterizedQuery>
</Lookup>
<RowCount Name="Row Count" VariableName="User.Variable" />
</Transformations>
</Dataflow>
In the above snippet, I generate a pair of number, 100 and 11 as col and then route to a Lookup component that has hardcoded values of 1 and 100. Since I expect to match, if I ran it as-is, it'll blow up on the unmatched 11 value.
My Dataflow's ExternalProperty override then injects the "missing" at run time to save my lookup from blowing up.
In your case,
I didn't attempt to do this for a partial cache but I can't imagine the syntax will be much different, but I'd fix the code by hand one time and then reverse engineer the package. BimlExpress now provides that functionality for free and it's awesome for answering the "how do I express Y in Biml?" Right click on the package and there's a Convert to Biml option (name approximate)

Answer 2

Billinkc's answer as correct. It was, in essence:
ExternalProperty=[etc], not "PropertyName", and in order for it to work it requires a valid query to generate.