The <pipe> element is used to display information conditionally.
Using <case> elements, you can specify any number of conditions to be evaluated from top to down. The first case to resolve to True is used and the corresponding text is displayed. The <pipe> element is translateable and will be properly pulled by the translation system.
For example:
<number label="Q1" size="2" verify="range(0, 10)"> <title>How many children do you have?</title> </number> <suspend/> <pipe label="children_have"> <case label="c1" cond="Q1.ival == 1">Has your child</case> <case label="c2" cond="Q1.ival gt 1">Have your children</case> <case label="c3" cond="1">no children</case> </pipe> <radio label="Q2" optional="0" cond="Q1.ival"> <title>[pipe: children_have] been to the zoo in the past 6 months?</title> <row label="r1">Yes</row> <row label="r2">No</row> </radio> <suspend/>
All <pipe> elements must specify cond="1" for the last <case> element. This will be the default case to use when all others evaluate to False. In the example above, "c3" will be referenced only when Q1 is 0.
A Single-Select question is generated in the report containing each possible case and the last case referenced for each participant.
1: Attributes
The <pipe> element has access to the following attributes:
1.1: label - Set the Pipe Name
The label attribute is the unique identifier for the <pipe> element. This is used as a reference when piping the data.
<radio label="Q1" optional="0">
<title>Are you...</title>
<row label="r1">Male</row>
<row label="r2">Female</row>
</radio>
<suspend/>
<pipe label="gender">
<case label="c1" cond="Q1.r1">men</case>
<case label="c2" cond="Q1.r2">women</case>
<case label="c3" cond="1">undefined</case>
</pipe>
<html label="Introduction" where="survey">
<p>This survey is meant to find out about the shopping habits of ${pipe.gender} like you.</p>
<p>Please click "Continue" to take the [pipe: gender]'s portion of this study.</p>
</html>
<suspend/>
Tip: You can reference the <pipe> element using the ${pipe.LABEL} or [pipe: label] syntax.
1.2: capture - Set the Data Variable Name
The capture attribute overrides the default label for the auto-generated Single-Select question that the <pipe> element produces.
For example, the following <pipe> element automatically generates a variable named pipe_MyPipe.
<pipe label="MyPipe">
<case label="c1" cond="1">Some Text</case>
</pipe>
We can use the capture attribute to rename this variable, overriding pipe_MyPipe to SomethingSpecial.
<pipe label="MyPipe" capture="SomethingSpecial">
<case label="c1" cond="1">Some Text</case>
</pipe>
1.3: title - Set the Data Variable Title
The title attribute overrides the default title of the auto-generated Single-Select question that the <pipe> element produces.
For example, the following <pipe> element automatically generates a variable named SomethingSpecial with pipe_MyPipe as the title.
<pipe label="MyPipe" capture="SomethingSpecial">
<case label="c1" cond="1">Some Text</case>
</pipe>
Note: MyPipe is the original label of the <pipe> element. The default title for a <pipe> element is: Pipe LABEL.
You can use the title attribute to provide a custom title for the <pipe> element.
<pipe label="MyPipe" capture="SomethingSpecial" title="My Special Title">
<case label="c1" cond="1">Some Text</case>
</pipe>
2: Pipe Transformation Functions
There are a number of transformation functions that can alter the content of the <pipe> element as it is displayed in the survey.
| Transformation | Description | Example |
|---|---|---|
| upper | Upper-cases all letters of the pipe (e.g., PIPE TEXT LOOKS LIKE THIS) |
[pipe: LABEL upper] |
| lower | Lower-cases all letters of the pipe (e.g., pipe text looks like this) |
[pipe: LABEL lower] |
| title | Title-cases all letters of the pipe (e.g., Pipe Text Looks Like This) |
[pipe: LABEL title] |
| capitalize | Capitalizes the first letter of the pipe (e.g., Pipe text looks like this) |
[pipe: LABEL capitalize] |
For example:
<pipe label="Test_Pipe">
<case label="c1" cond="1">what does the FOX say?</case>
</pipe>
<html label="Test_Comment" where="survey">
<p>[pipe: Test_Pipe]</p>
<p>[pipe: Test_Pipe upper]</p>
<p>[pipe: Test_Pipe lower]</p>
<p>[pipe: Test_Pipe title]</p>
<p>[pipe: Test_Pipe capitalize]</p>
</html>
The code above produces the following result:
3: Example
The <pipe> element is useful if you want to display any text based on a question's logical conditions. For example, it can be used to display concept images to participants based on a randomly assigned marker.
| Concept 1 | Concept 2 | Concept 3 |
|---|---|---|
 |
 |
 |
In the example below, a quota is called to immediately assign one of three random markers and use these markers to show one of the concept images shown above.
<quota label="ConceptPicker" sheet="concept"/>
<radio label="vConcept" optional="0" where="execute">
<exec>
for x in xrange(3):
if hasMarker('concept_{}'.format(x+1)):
vConcept.val = x
</exec>
<title>The concept you were assigned is...</title>
<row label="r1">Concept 1</row>
<row label="r2">Concept 2</row>
<row label="r3">Concept 3</row>
</radio>
<suspend/>
<pipe label="concept">
<case label="c1" cond="hasMarker('concept_1')">
<p>CONCEPT 1 TITLE</p>
<p><img src="[rel concept_1.png]" class="concept"/></p>
</case>
<case label="c2" cond="hasMarker('concept_2')">
<p>CONCEPT 2 TITLE</p>
<p><img src="[rel concept_2.png]" class="concept"/></p>
</case>
<case label="c3" cond="hasMarker('concept_3')">
<p>CONCEPT 3 TITLE</p>
<p><img src="[rel concept_3.png]" class="concept"/></p>
</case>
<case label="c4" cond="1">UNDEFINED</case>
</pipe>
<html label="ShowConcept" where="survey">
<p>Please take a look at the following concept.</p>
<p>[pipe: concept]</p>
</html>
<suspend/>
The code above uses the <pipe> element to produce the following result if assigned concept 1:
4: Learn more
Learn about the Piping Tool if you are using the Survey Editor.
Learn about the Resource tag, another great element that can be combined with the <pipe> element to produce dynamic content.
For example, we can rewrite the example above using a <res> and <pipe> element to achieve the same effect with lesser lines of code.
Tip: Instead of repeating the same content for each case, you can write it once using a <res> element and use the built-in Python function, format, to replace only the changing parts (e.g., the concept number).
<quota label="ConceptPicker" sheet="concept"/>
<radio label="vConcept" optional="0" where="execute">
<exec>
for x in xrange(3):
if hasMarker('concept_{}'.format(x+1)):
vConcept.val = x
</exec>
<title>The concept you were assigned is...</title>
<row label="r1">Concept 1</row>
<row label="r2">Concept 2</row>
<row label="r3">Concept 3</row>
</radio>
<suspend/>
<res label="concept_text">
<p>CONCEPT {0} TITLE</p>
<p><img src="[rel concept_{0}.png]" class="concept"/></p>
</res>
<pipe label="concept">
<case label="c1" cond="hasMarker('concept_1')">${res.concept_text.format(1)}</case>
<case label="c2" cond="hasMarker('concept_2')">${res.concept_text.format(2)}</case>
<case label="c3" cond="hasMarker('concept_3')">${res.concept_text.format(3)}</case>
<case label="c4" cond="1">UNDEFINED</case>
</pipe>
<html label="ShowConcept" where="survey">
<p>Please take a look at the following concept.</p>
<p>[pipe: concept]</p>
</html>
<suspend/>