tiny question about ApplyMap syntax

[#1]

I was reading the great explanation regarding ApplyMap by Steve Dark

http://www.quickintelligence.co.uk/applymap-is-it-so-wrong/

a question came up in my mind:

if I have

MapProducts:
MAPPING LOAD
ProductID,
description;

LOAD
Order
ApplyMap('MapProducts',ProductID,'N/A') as Item
RESIDENT Order_table;

is this expected to work perfectly, since I am not explicitly loading ProductID from the resident Order_table?

Further, by using this syntax, I should NOT expect to see the field ProductID in the dashboard, right?

thank you!

[swuehl · Accepted solution]

I think your Mapping load misses a data source (FROM, RESIDENT etc.).

You don't need to explicitely load the ProductID in your table, and using above load you should not expect to see the ProductID field in your data model.

[#3]

I think you would have to type this:

'drop table Order_table';

at the end

to not have ProductId...

[Clever_Anjos]

You creating your mapping table from your source table. It won´t work.

You should populate your Mapping Table before using it (inline, excel, whatever)

[#5]

MapProducts: 

MAPPING LOAD  ProductID,  description

from <table>;

tab2:

  LOAD  Order,  ApplyMap('MapProducts',ProductID,'N/A') as Item  RESIDENT Order_table; 

drop table Order_table;

[#6]

indeed, I left aside the RESIDENT for the mapping load, excuses.

And true that, ProductID will be appearing if Order_table is not Dropped.

But indeed, if Order_table is dropped, I understand ProductID is not going to be shown through the ApplyMap.

It is used to ApplyMap but not kept.

thank you for the answers!