CommCare – How to Filter Instances by Case Property

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I am working on the CommCare mLabour app, which tracks women from the onset of labour through delivery via digital partograph. For the contractions graph, I need to write an instance which filters to cases whose contraction intensity is 'low'. In the app, this case property is contractions_dur = 'low'. I tried the following path, and am getting an xpath error in the app:

instance('casedb')/casedb/case[@case_type='Indicators'][index/parent=current()/@case_id][@status='open']/[contractions_dur = 'low']

The error message says invalid xpath 'expected beginning of path'

The only CommCare Help Site page I can find about instance syntax is this one about CommCare session instance paths. What is the proper syntax for an instance filtering for a specific case with a certain case property value?

Best Answer

If you're filtering cases, you want an expression that ultimately returns a set of cases. The first part of the expression, instance('casedb')/casedb/case, gives you all cases on the phone.

The expressions in square brackets then filter the cases by case type, parent (you're limiting to cases that are children of the "current" case, which is the one you selected from the case list), and open/closed.

[@case_type='Indicators']
[index/parent=current()/@case_id]
[@status='open']

The /[contractions_dur = 'low'] is what's throwing the error. The / says to go another level deep, but I suspect what you want is to just add the contractions_dur as a fourth constraint, on the same level as the others. So try dropping the slash: instance('casedb')/casedb/case[@case_type='Indicators'][index/parent=current()/@case_id][@status='open'][contractions_dur = 'low']

Create a hidden variable with your label text

Add the label text to the Calculate Condition of a hidden variable question type. For example, my_label_text

Reference that variable in a question's label text box

You can drag and drop that hidden variable, my_label_text, into the label portion of the question:

Save the hidden variable to a case property

You can then add logic to save my_label_text as a case property in the Case Management tab. In your scenario you may also want to add logic to save whether or not the question was answered properly.

CommCare – Instance Syntax to Search for All Child Cases of a Parent

I'm assuming in this case that you've loaded a the member case into your form, and that you can load the member case ID id into

/data/member_id

What you want to get is:

The count of all member cases which are children of this case's parent, for which the member case has the property mm_is_in_tb_treatment = 'yes'

For now we can create a new hidden value to store the parent household's case ID, since it'll make understanding the full query below easier.

New hidden value: /data/parent_id:

instance('casedb')/casedb/case[@case_id = /data/member_id]/index/parent

All cases which are children of that parent would be referenced as:

instance('casedb')/casedb/case[index/parent = /data/parent_id]

You can now add your new filter directly to the end of that statement and introduce the count

count(instance('casedb')/casedb/case[index/parent = /data/parent_id][mm_is_in_tb_treatment = 'yes']

If you wanted, you could further specify that you (for safety) only want to include children that are member cases and which are open. You can also collapse back the parent ID reference if you want a one-line expression:

count(instance('casedb')/casedb/case[@case_type='member'][@status='open'][index/parent = instance('casedb')/casedb/case[@case_id = /data/member_id]/index/parent][mm_is_in_tb_treatment = 'yes']

Best Answer

Related Solutions

CommCare – How to Save Label Text as Case Property for Later Reference

Create a hidden variable with your label text

Reference that variable in a question's label text box

Save the hidden variable to a case property

CommCare – Instance Syntax to Search for All Child Cases of a Parent

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