limer code examples

limer is an R package that enable R users to connect directly to a Lime Survey installation via its API (for details, see earlier post), essentially giving you remote control and a possibility of automating certain procedures.

Because the documentation of limer and the Lime Survey API is a bit minimal and therefore quite confusing for a first-time user, I give some simple coding examples below to get you started.

First, we connect to our Lime Survey instance, which is installed at LIMESURVEY.URL and can be accessed with a LIME.USERNAME and LIME.PASSWORD. Obviously you should replace these with your own installations’ details in the code below. The get_session_key() command gets you a unique key through which you can securely access the Lime Survey installation. This is automatically used in all the limer calls.

library(limer)

#LimeSurvey Server Info
options(lime_api = 'https://LIMESURVEY.URL/index.php/admin/remotecontrol')
options(lime_username = 'LIME.USERNAME')
options(lime_password = 'LIME.PASSWORD')

get_session_key()

The first example is a simple one that uses a built-in function from limer, get_responses. This simply allows you to download all the data (or only completed data) from a particular survey, #10001 in this case.

responses <- get_responses(10001, sCompletionStatus = 'all')

The second example requires greater knowledge of the LimeSurvey API language because the limer package does not have a neat wrapper for these functions. Instead the generic call_limer function is used in which calls from the original API can be introduced. The full guide of these API functions is available here.

The example below involves listing all the surveys on the Lime Survey installation (server) and then getting the number of completed responses. Note that the method inserted into the call_limer() function is the same method that is listed in the API documentation and the params are the arguments of that respective method. So in this sense, it’s actually quite straight forward

call_limer(method = "list_surveys") #list surveys on server

call_limer(method = "get_summary", #get number of completed responses
           params = list(iSurveyID = 10001,
                         sStatname = "completed_responses"))

The third and last example showcases some of the more sophisticated automation options. We aim to copy survey 123456, setup a participant table with two extra attributes: Institution and File, add one participant, activate the survey, compose the survey link and then, delete the survey.

When the initial survey is copied and users are created, details are stored in tmp and tmp2 because we wish to use these outputs and inputs for later functions.

The fromJSON function (which is from the JSONlite package) is also used to feed arrays with multiple pieces of data into the call_limer function. There might also be other ways to do this, but the below example works.

tmp <- call_limer(method = "copy_survey", #copy a survey
                  params = list(iSurveyID_org = 123456,
                                sNewname = 'The Copied Survey'))

call_limer(method = "activate_tokens", #setup participant table
           params = list(iSurveyID = tmp$newsid,
                         aAttributeFields = fromJSON('{"attribute_1":"Institution","attribute_2":"File"}')))

tmp2 <- call_limer(method = "add_participants", #add participant
                   params = list(iSurveyID = tmp$newsid,
                                 aParticipantsData = fromJSON('[{"email":"[email protected]","lastname":"Bond","firstname":"James","attribute_1":"Secret Service","attribute_2":"mi5","usesleft":999999}]'),
                                 bCreateToken = TRUE))

call_limer(method = "activate_survey", #activate survey
           params = list(iSurveyID = tmp$newsid))

paste0('https://LIMESURVEY.URL/index.php/', tmp$newsid, '?token=', tmp2$token, '&newtest=Y') #generate survey link

call_limer(method = "delete_survey", #delete the survey
           params = list(iSurveyID = tmp$newsid))

As is hopefully clear now, the limer package offers some powerful options for automating the setting up of surveys as well as importing the data into R.

Finally, its good practice to close off the session with the following call.

release_session_key()

Lime Survey and R: limer

Lime Survey is (probably) the world’s most popular open source survey package and R is the world’s most popular open source statistical and data analysis software (probably). So it seems only natural that there should be a bridge between the two: where the limitations of Lime Survey begin, R can take over and vice-versa.

Thankfully the bridge has been laid by an R package called limer. limer uses the API functionality that is built into Lime Survey to make calls to a Lime Survey instance. The most useful of these is probably the ability to get survey responses. But there is a wealth of other options too, including copying and deleting surveys, getting survey statistics, etc.

The github page of limer provides instructions on how to install it and how to make some basic calls. You also need to enable the API in your Lime Survey installation, which you can do under Settings –> Global Settings –> Interfaces. Be sure to set it to “JSON-RPC” and you will also see the URL to access the API (see image below)

Details on the Lime Survey API are available, although admittedly the documentation is a bit thin.

Assuming you have configured your Lime Survey instance with an SSL certificate (giving the https:// URL), the connection between R and Lime Survey is also encrypted and therefore any personal or sensitive data being exchanged between Lime Survey and R, is secured.

limer coding examples are to follow in a later post.