Hey everyone,
I wanted to share some insights on using the %e DREL expression to extract answers from repeatable sections in TrueContext forms.
Background
The %a[question_id] DREL expression extracts answers for a specific question. However, when used in a repeatable section, it retrieves answers from every row in that section. Consider a repeatable section, Grocery List that has 3 rows of answers. The DREL expression %a[Item Name] would return the answer from every row, Bread Milk Eggs.
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Repeatable Section (ID: Grocery List)
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Question (ID: Item Name)
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Question (ID: Item Quantity)
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Question (ID: Purchased?)
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Bread
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2
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true
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Milk
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1
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false
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Eggs
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3
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true
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Solution: The %e Expression
The %e[repeatable_section_id] expression retrieves answers from a specified repeatable section.
Filtering by Row
To extract answers from a specific row, use:
- %e[repeatable_section_id][n] – Extracts all answers from row n (0-based index).
- %e[repeatable_section_id][n][inner_drel] – Extracts answers from row n using an inner DREL expression.
Based on the repeatable Grocery List data found above, these expressions give the following results:
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DREL Expression
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Result
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%e[Grocery List]
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Bread 2 true Milk 1 false Eggs 3 true
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%e[Grocery List][0]
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Bread 2 true
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%e[Grocery List][1][Buy: %a[Item Name] x %a[Item Quantity]]
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Buy: Milk x 1
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Format Answers with a Delimiter
When extracting answers, use a delimiter to separate them.
Syntax
%e[repeatable_section_id][inner_drel][delimiter]
- inner_drel: Specifies which answers to extract.
- delimiter: Separates the answers.
Example
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DREL Expression
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Result
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%e[Grocery List][%a[Item Name]][, ]
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Bread, Milk, Eggs
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%e[Grocery List][%a[Item Quantity]][ + ]
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2 + 1 + 3
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Nested Repeatable Answers
When a repeatable section contains another repeatable section, use %e within an inner_drel expression.
- %e[repeatable_section_id][0..n][%e[nested_repeatable_section_id][0..n][inner_drel]]]
Consider data for a Store List section that contains a nested Grocery List as follows:
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Repeatable Section (ID: Store List)
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Question (ID: Store Name)
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Repeatable Section (ID: Grocery List)
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Question (ID: Item Name)
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Question (ID: Item Quantity)
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Question (ID: Purchased?)
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Loblaws
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Bread
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2
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true
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Milk
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1
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false |
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Eggs
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3
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true
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Walmart
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Batteries
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5
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false
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Pillows
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2
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false
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These expressions give the following results:
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DREL Expression
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Result
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%e[Store List][1][%e[Grocery List]]
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Batteries 5 false Pillows 2 false
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%e[Store List][1][%e[Grocery List][0]]
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Batteries 5 false
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%e[Store List][0][Buy: %e[Grocery List][2][%a[Item Name]] from %a[Store Name]]
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Buy: Eggs from Loblaws
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%e[Store List][0][%a[Store Name] Items: %e[Grocery List][%a[Item Name]][, ]]
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Loblaws Items: Bread, Milk, Eggs
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For more detailed information, refer to the DREL Complete Reference List in our documentation.
Hope this helps!
#TechTalkImplementation
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Rob Dods
Analytics Implementation Specialist
TrueContext
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