Overview
In its basic form, the Case list and Case details definition pages only accept case properties of the module case type. However, there is an addon that allows the use of calculations in the case list/details, called Custom Calculations in Case List. In addition to calculations, the add-on also opens the possibilities beyond the module case type, allowing access to any fixture available in the user’s restore file.
Enabling the Add-on
To turn on this feature, proceed to the Application Settings (1) -> Add-ons section (2) of the application:
Next, select the button with three-lines in the upper right hand corner and choose “Calculations” (3):
In the Calculation section, check the option “Custom Calculations in the Case List” Add-on (4) and hit save (5) to commit the changes.
Using the Feature
Once the Add-On has been enabled, a new option will appear in the Add Property dropdown list (1) in the Case List or Case Detail definition pages, selecting Calculated Property (2) will create a new field in which it’s possible to define an XPath expressions to perform calculations (3), including these use of case properties.
Writing expressions
Case properties and attributes in Calculated properties are evaluated the same way as Properties in Case List and Details, as long as they are within the scope of the current case being iterated over. For instance, if the selected property is age, Commcare will actually execute “current()/age”. For properties outside the scope, a full XPath query expression is required. See some examples below.
Calculations within the scope
| Type | Description | Expression | Example |
|---|---|---|---|
| Case attributes | Displays the ID of the current case | current()/@case_id |
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| Case indexes | Displays the ID of the parent case of the current case | current()/index/parent |
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| Case properties | Displays the value of the property | current()/age |
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| Mathematical Calculation | Returns the estimated Date of birth according to the Age stored in the case | date(floor(today() - (current()/age * 365.25))) |
|
Calculation beyond the scope
| Type | Description | Expression | Example |
|---|---|---|---|
| Calculation involving the parent case | Displays the name of the Parent case | instance('casedb')/casedb/case[@case_id=current()/index/parent]/case_name |
|
| Calculation involving child cases | Returns the number of child cases | count(instance('casedb')/casedb/case[@case_type='member'][index/parent=current()/@case_id]) |
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| Calculation involving User properties | Checks whether the User is assigned to the same location as the patient | if(instance('commcaresession')/session/user/data/commcare_location_id=village_id,"YES","NO") |
|
| Calculation involving Locations | Retrieves a location's name based on information stored in the case | instance('locations')/locations/location[@id=current()/village_id]/name |
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| Calculation involving Lookup tables | Retrieves a field of a Lookup table item based on information stored in the case | instance('item-list:medicine')/medicine_list/medicine[index=current()/medication_index]/medication |
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