Variable for csv filename in pull-data

[Josh]

Hi @nancyv, @wroos, this is related to the discussion here about trying to include images dynamically.

How to Pulldata Images

Hi @dedik2urniawan, I think this approach might not work as expected since Enketo pulls referenced images on page loading (at least in my testing). An alternative approach could be to do something like this: If you have four images, blue_pill.png, red_pill.png, blue_ball.png and red_ball.png then you can display them variably with a relevant condition: survey type name label relevant media::image calculation select_one colours colour Colour select_one objects object Object c…

Unfortunately, Enketo resolves the URLs (jr://...) on the backend and fetches the external data when the form is first loaded — therefore it needs to know the filename upfront. You can see this difference in the XML of the XLSForm, one with a dynamic filename and one fixed (example from the XLSForm docs on pulldata):

survey 1

type	name	label	calculation
calculate	filename		‘fruits’
calculate	fruit		pulldata(${filename}, ‘name’, ‘name_key’, ‘mango’)
note	note_country	The fruit ${fruit} is pulled csv data.

survey 2

type	name	label	calculation
calculate	fruit		pulldata(‘fruits’, ‘name’, ‘name_key’, ‘mango’)
note	note_country	The fruit ${fruit} is pulled csv data.

@@ -14,10 +14,10 @@
           </meta>
         </aUJ4gsohDFa8wmxGiSs5Dg>
       </instance>
-      <instance id="${filename}" src="jr://file-csv/${filename}.csv"/>
+      <instance id="fruits" src="jr://file-csv/fruits.csv"/>
       <bind calculate="'fruits'" nodeset="/aUJ4gsohDFa8wmxGiSs5Dg/filename" type="string"/>
       <bind nodeset="/aUJ4gsohDFa8wmxGiSs5Dg/n" readonly="true()" type="string"/>
-      <bind calculate="pulldata( /aUJ4gsohDFa8wmxGiSs5Dg/filename , 'name', 'name_key', 'mango')" nodeset="/aUJ4gsohDFa8wmxGiSs5Dg/fruit" type="string"/>
+      <bind calculate="pulldata('fruits', 'name', 'name_key', 'mango')" nodeset="/aUJ4gsohDFa8wmxGiSs5Dg/fruit" type="string"/>
       <bind nodeset="/aUJ4gsohDFa8wmxGiSs5Dg/note_country" readonly="true()" type="string"/>
       <bind jr:preload="uid" nodeset="/aUJ4gsohDFa8wmxGiSs5Dg/meta/instanceID" readonly="true()" type="string"/>
     </model>

In the network tab of your browser’s dev tools, you can see that the form with a dynamic filename does not make a GET request for the data, but when the filename is declared upfront you can see:

Additionally, you can see the difference in how Enketo resolves these URLs in the response to the POST request made to /transform/xform:

@@ -14,5 +14,5 @@
             </meta>
         </aUJ4gsohDFa8wmxGiSs5Dg>
     </instance>
-    <instance id="${filename}" src="jr://file-csv/${filename}.csv"/>
+    <instance id="fruits" src="/media/get/https/kc.kobotoolbox.org/joshuaberetta/xformsMedia/970740/1564798.csv"/>
 </model>

So in summary, you will have to do something similar to what I recommended in the linked thread where you load all external data and then reference it inside the form in a dynamic way. Hope that helps