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Survey Engine Expressions

Expression is a a general concept used in several places of the Influenzanet Survey System. Before reading this page you should read the general concept of expressions.

Logical Expression​

Logical expressions evaluate the logical operations using boolean result of one or several expression evaluated value. Each expression argument is evaluated and casted as boolean

  • Numerical result : true if > 0, and false if <= 0
  • String result : true if not empty, false if empty (=='')

Several operators are available:

  • and(e1, e2) : AND operator (true if e1 is true AND if e2 is true)
  • or(e1, e2) : OR operator (true if e1 is true OR if e2 is true)
  • not(e1): NOT operator (true if e1 is false, false if e1 is true)
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Comparison operators​

  • eq(e1, e2, ..., en) : Equal operator, true if all operators are equals, if e1 === e2 (... === en)
  • gt(e1, e2) : Greater than operator (true if e1 > e2)
  • gte(e1, e2) : Greater or equal operator (true if e1 >= e2)
  • lt(e1, e2) : Lower than operator (true if e1 < e2)
  • lte(e1, e2) : Lower or Equal operator (true if e1 <e; e2)

Nota: The Javascript implementation uses the '===' operator, checking for value AND type for equality.

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Utilities​

isDefined()​

isDefined Operator test if an expression returns a defined value (i.e. the value is not undefined nor null for javascript engine).

getContext()​

getContext returns the current Runtime Context, allowing to get Participant attributes

getAttribute(object, name)​

Extract a attribute from an object

This is a low level function Common case is to extract attribute from the context, to check for a Participant flag.

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Fortunately CASE Editor Tools provides some helpers to generate such complex expressions

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Responses expressions​

These expressions are used to get and test the current survey responses.

hasResponse(item_key, rg_key):boolean​

Check if an item has a specific response object (by key)

  • item_key: key of the item (question)
  • rg_key : path of the response component from the root in the question
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getResponseValueAsNum(item_key, rg_key):number​

Get the response value of an Response component of an Item, and parse it as numeric value

  • item_key: key of the item (question)
  • rg_key : path of the response component in the item.

getResponseValueAsStr(item_key, rg_key): string​

Get the response value of an Response component of an Item as a string

  • item_key: key of the item (question)
  • rg_key : path of the response component in the item.

responseHasKeysAny(item_key, rg_key, option_key...):boolean​

Test if the response component of a item as any response key from the option_key list of value. This expression is used to test if the current response of a categorical component have at least one response in a given list options are identified by their key value.

  • item_key: key of the item (question)
  • rg_key : path of the response component in the item.
  • option_key... : one or several key of option

responseHasKeysAll(item_key, rg_key, option_key...):boolean​

Same as responseHasKeysAny, but test if the current response include all the provided option key

For example, if the question intake.Q1 has the current response 'cat' AND 'dog'

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responseHasOnlyKeysOtherThan(item_key, rg_key, option_key...):boolean​

Same as responseHasKeysAny, but test if the current response DOES NOT include any option key in the provided list

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checkResponseValueWithRegex(item_key, rg_key, pattern ):boolean​

Check if the response of an item match a the given Regular Expression pattern. The pattern is using Javascript ECMAScript Regular Expression

Only online

countResponseItems(item_key, rg_key):number​

Count the number of responses selected in a Response component of an item.

If the item is not found or no response is provided yet, the expression will return -1 value.

Validation​

getSurveyItemValidation(item_key, validation_key)​

Time functions​

timestampWithOffset(offset, refTime)​

  • offset is the number of seconds to add to the reference time
  • refTime is the reference time (if not provided the current time will be used)

Both are evaluated to number but they can be expressions.

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getSecondsSince(time):number​

Returns the number of seconds from the given time and the current time.

time must be evaluated to a Unix timestamp (number of seconds since 1970-01-01), it can be an expression returning the timestamp (Date and time response component returns response as timestamp value)

dateResponseDiffFromNow(item_key, rg_key, ?unit, ?unsigned)​

Evaluate time difference from now using response of an item

  • item_key: key of the item (question)
  • rg_key : path of the response component from the root in the question (always starts with 'rg.' representing the Response Group Component)
  • unit : time unit to use as output, accepted values are 'years', 'months', 'weeks', 'hours', 'minutes', 'seconds'
  • unsigned: flag to have a unsigned result (ignore sign of the result) if the value is evaluated to true (e.g. 1), otherwise result can output negative value.

Low level expression​

Most of the time you wont need these expression, but in some case it's necessary to use them.

getResponses()​

getRenderedItems()​

getArrayItemAtIndex()​

getArrayItemByKey()​

getObjByHierarchicalKey()​

getNestedObjectByKey()​

findPreviousSurveyResponsesByKey()​

getLastFromSurveyResponses()​

getPreviousResponses()​

filterResponsesByIncludesKeys()​

filterResponsesByValue()​

getLastFromSurveyItemResponses()​

getResponseItem()​

parseValueAsNum(value):number​

Evaluate the argument value (can be an expression), and parse it to number