This page will walk through an example of setting up a form that both displays conditional options in lists (list of districts from chosen state) and has options that are specific to each user.
First setup the following two tables using the Creating and Updating Lookup Tables page. You can use whichever mobile workers or groups that you have in your project.
|field: id||field: name||user 1||group 1|
|up||Uttar Pradesh||supervisor||Uttar Pradesh Users|
|field: id||field: name||field: state_id||user 1||group 1|
|agra||Agra||up||supervisor||Uttar Pradesh Users|
|faizabad||Faizabad||up||supervisor||Uttar Pradesh Users|
Our sample creates two tables (state and district). The district table has three fields (id, name and state_id). The state_id will be used to filter the list of districts based on the selected state. The following image shows our final setup.
Including Lookup Table Information in the Form
Once we've defined a lookup table, we need to reference it in our form. This is done by adding an "instance" line that references the name of the table. You can place this above any existing <instance> lines in your form.
You can choose any word for the id="__" portion. This is how you'll reference your lookup table in the rest of the form. For the src="jr://fixture/item-list:____" section, you must specify the "Tag" that you created the table with.
Create a Select List Based on a Lookup Table
To create a select list based on a lookup table, first add a single select question to your form. In our example, we'll add two single select questions, "state" and "district". Note: you cannot have any answer options associated with the single select question. Delete all answer options in the form buidler, otherwise you will get an error.
Now in your form's XML, find the "select1" tag that corresponds to your question and add an "itemset" tag that references your lookup table. This will display that lookup table's rows as select choices. Make the changes highlighted in Red.
<label ref="jr:itext('state-label')" />
<label ref="jr:itext('district-label')" />
<value ref="id" />
The itemset tag references the instance you specified, and the data within that instance. This is typically in the format "[lookup_table_tag_name]_list/[lookup_table_tag_name]". We have also added label and name tags under each itemset. This references the field in the lookup table that we want to use as the display and what we want to use as the value.
If you were to test this application, you'd see the first question displays a list of all states and the second question displays a list of all districts (irrespective of the selected state). To filter the district list, we need to add a filter condition to the itemset.
Filtering the ItemSet
To filter an item set, we use Xpath expressions (similar to the expressions used when defining Display Logic or Calculations in your form). In our example, we'll filter the District item list based on the selected state. Our district table contains a field called "state_id". The values in this match the value specified for the state question. The filter is added in square brackets in the item set.
<label ref="jr:itext('district-label')" />
<itemset nodeset="instance('districts')/district_list/district[state_id = /data/state]">
<value ref="id" />
You can write complex logic within the square brackets. To reference the value of another question, use the "/data/<question_id>" format. To reference a field within the table row, just use its name (ex. state_id).
Testing an application with lookup tables
In order to test the conditional select options and other logic works in the application, you must sign on as a mobile user and submit 'real' data to the server. If you see an error when opening the form that states "Could not find an appropriate fixture for src: jr://fixture/item-list:table_name" you have not properly setup your lookup tables.
- Sync your application. Some users have reported this error with large lookup tables that have not properly downloaded which choosing "Update Commcare" from the menu. Run the sync to ensure all assets are properly downloaded to the device
- Make sure that the current user has lookup table rows assigned to them (Creating and Updating Lookup Tables)
- Alternatively, setup your lookup table so that it is available for all users (For the lookup table, set it up so that it is "Visible to All Users" by clicking Edit Type).
- Once you've done this, make sure you've synced your phone.
If you run into issues testing your app with lookup tables, try these two troubleshooting options:
Check to see if the table is visible to your mobile user: To check whether or not the lookup table is visible to your user, go to this link: http://www.commcarehq.org/hq/admin/phone/restore/?as=[mobile username]@[domain]&version=2.0 If the table is visible to your user, you should see the table appear in the XML payload.
Clear user data: After you sync your phone if the lookup table still is not working, you may need to clear user data and log-in again. To do this, go to the login screen and click on Settings. After the Settings screen shows up, click the menu button, and select the first option, "Clear User Data." This will clear the username and force you to re-enter login credentials. Once you log in again, the new or edited table should be accessible to your user.
Large lookup tables may cause an error on the mobile device stating "get field slot from row 0 col 1 failed." This is due to the amount of memory allocated to the lookup table on the mobile device. The lookup table is larger than the available memory. If you get this error, a common work around is to split the table into multiple tables. This can be completed by adding a "more" option to the bottom of your first lookup table and performing a conditional question to display the results of the second lookup table if "more" is selected. For example, there are more than 3,600 Village Development Committees (VDC) in Nepal across 75 districts. One user created a conditional select option to display the VDCs within the selected district. However, the VDC list was too large to display in one lookup table. The user created three lookup tables that each supported the VDCs of 25 districts. Three VDC questions were created with conditional criteria that displayed the VDCs from one of the three lookup tables. Finally, a calculated question was created to determine which VDC was selected from the three VDC questions.
Training an application with lookup tables
- Generic User: Create a generic user called "dimagi" or "demo" and update the table specifically for this user - populating all the conditional select options with the same 'dimagi' or 'demo'. As long as the partner is aware of the use case, they will be able to filter out this user in reports. During training, mobile users will sign onto CommCare and submit live 'practice' data. Work with the partner to specify a date where all data submitted to CommCare HQ is considered actual data for program purposes. This should be made clear to the FLWs and to the data analyst/M&E officer.
- Training Application: Copy the final application - remove the conditional select options from the application. This app can be used during training as a training application and the users can enter data in demo mode.
- No SIM: If the partner has not secured SIM cards for the phones prior to training, install CommCare on all the phones. Use one SIM card to restore the user or practice user ('dimagi' or 'demo') to all phones. The phone will update according to the latest lookup table on HQ. Remove the SIM. The conditional select options will work on the phones and the data will not be submitted to the CommCare HQ.