ExpressionScript Hoe te gebruiken

Samenvatting van andere uitleg over Expressiebeheer

Als je de index van de LimeSurvey-handleiding tot nu toe hebt gevolgd, betekent dit dat je de LimeSurvey-terminologie al kent. We hebben expressies en variabelen behandeld om te laten zien hoe we onze enquêtes kunnen verbeteren. Daarna zijn we overgegaan op de manieren en betekenissen van syntax highlighting om te laten zien hoe je syntaxisfouten kunt verbeteren.

Met dit als kennis kunnen we naar de voorbeelden gaan en laten zien hoe expressies werken in LimeSurvey.

Syntax highlighting

De volgende screenshots geven voorbeelden zonder de tooltips. Een tooltip is een informatieve box die wordt weergegeven wanneer je de muisaanwijzer op een vetgedrukt woord plaatst.

Door de markering van de syntaxis is het eenvoudig om correcte gecompliceerde expressies samen te stellen. Hoewel het LimeSurvey-team van plan is om een ​​grafische gebruikersinterface te maken, kunt je de bestaande highlighting gebruiken om fouten snel te identificeren en op te lossen. Je kunt de tooltips ook gebruiken om de nauwkeurigheid van de expressies te valideren (bijv. bevestig dat je de gewenste variabele(n) hebt geselecteerd).

In elk voorbeeld zijn er drie kolommen:

1. Source : dit is de onbewerkte tekst die je zou invoeren in het LimeSurvey-vragenveld.
2. Pretty Print : dit is het syntaxis-gemarkeerde equivalent.
3. * Merk op dat uitdrukkingen worden weergegeven met een tan achtergrond, maar niet omringd door accolades in deze markering.
4. * Aangezien expressiebeheer recursieve vervanging ondersteunt, zou het tonen van accolades in de markering syntaxisfouten veroorzaken.
5. Result : dit is de output die wordt gegenereerd wanneer expressiebeheer de invoer verwerkt.
6. * Alles dat goed kan worden vervangen is.
7. * Expressies met fouten worden in-line getoond, met syntax highlighting. Fouten worden omgeven door een rood-omlijnd veld.

Juiste syntaxis

You may find below examples of proper syntax:

1. Values: shows that known variables are color coded according to whether are set on the current page. Old-style INSERTANS:xxxx gets its own color-coding style
2. Question Attributes: shows that dot notation can access some properties of questions
3. Math: shows that basic and complex calculations are supported
4. TextProcessing: shows some of the available text-processing functions
5. Dates: shows two of the available date-related functions
6. Conditional: shows the usage of the if() function. The choices can be nested.
7. Tailored paragraph: you can completely customize a report based upon prior values
8. EM processes within strings: shows that it can do substitutions within strings. This example generates a tailored image name.
9. EM doesn't process curly braces like these: shows that if the curly braces are escaped, or there is a white space between the expression and the curly braces, EM ignores the expression.

Syntaxis met fouten

Here are examples of common errors when typing EM expressions. Note that the tooltips provide additional information.

1. Inline Javascript that forgot to add spaces after curly brace
   • Since "document.write" appears right after a curly brace, EM thinks it is an expression, and red-boxes "document" and "write" since they are undefined variable and functions, respectively
2. Unknown/Misspelled variables, functions and operators
   • Here we forgot that we are using the variable name "gender" instead of "sex", but EM catches that error. It also red-boxes '++', since that is not a supported operator.
3. Warns if use = instead of eq, or perform value assignments
   • Note that the '=' and '+=' are in red text instead of black. If you hover the mouse over them, you will see warnings that you are assigning a value.
4. Wrong number of arguments for functions
   • if() takes 3 arguments, but it has been given 4, so hovering over the red-boxed "if" will explain the error and show the supported syntax
   • sum() takes an unlimited number of arguments, but we had a trailing comma before the closing parentheses, so that is red-boxed
5. Mismatched parentheses
   • This is one of the most common errors when writing expressions.
   • This shows two examples of missing closing parentheses, and one example of having one too many closing parentheses.
6. Unsuported syntax
   • If you use an operator or punctuation that EM does not support, it will red-box it.
7. Invalid assignments
   • Some variables are readWrite and can have their values changed. Others are read-only.
   • If you try to change the value of a read-only variable, you can't. EM will red-box the attempt.
   • If you try to assign a value to an equation or a string, you will also get an error

"Live" voorbeelden van syntaxis markering met actieve tooltips

Source	Pretty Print	Result
Here is an example of OK syntax with tooltips Hello {if(gender=='M','Mr.','Mrs.')} {surname}, it is now {date('g:i a',time())}. Do you know where your {sum(numPets,numKids)} chidren and pets are?	Here is an example of OK syntax with tooltips Hello if(gender == 'M','Mr.','Mrs.') surname, it is now date('g:i a',time()). Do you know where your sum(numPets,numKids) chidren and pets are?	Here is an example of OK syntax with tooltips Hello Mr. Smith, it is now 6:07 am. Do you know where your 3 chidren and pets are?
Here are common errors so you can see the tooltips Variables used before they are declared: {notSetYet} Unknown Function: {iff(numPets>numKids,1,2)} Unknown Variable: {sum(age,num_pets,numKids)} Wrong # parameters: {sprintf()},{if(1,2)},{date()} Assign read-only-vars:{TOKEN:ATTRIBUTE_1+=10},{name='Sally'} Unbalanced parentheses: {pow(3,4},{(pow(3,4)},{pow(3,4))}	Here are common errors so you can see the tooltips Variables used before they are declared: notSetYet Unknown Function: iff(numPets > numKids,1,2) Unknown Variable: sum(age,num_pets,numKids) Wrong # parameters: sprintf(),if(1,2),date() Assign read-only-vars:TOKEN:ATTRIBUTE_1+=10,name='Sally' Unbalanced parentheses: pow(3,4,(pow(3,4),pow(3,4))	Here are common errors so you can see the tooltips Variables used before they are declared: notSetYet Unknown Function: iff(numPets > numKids,1,2) Unknown Variable: sum(age,num_pets,numKids) Wrong # parameters: sprintf(),if(1,2),date() Assign read-only-vars:TOKEN:ATTRIBUTE_1+=10,name='Sally' Unbalanced parentheses: pow(3,4,(pow(3,4),pow(3,4))
Here is some of the unsupported syntax No support for '++', '--', '%',';': {min(++age, --age,age % 2);} Nor '|', '&', '^': {(sum(2 | 3,3 & 4,5 ^ 6)}} Nor arrays: {name[2], name['mine']}	Here is some of the unsupported syntax No support for '++', '--', '%',';': min( ++ age, -- age,age % 2) ; Nor '|', '&', '^': (sum(2 | 3,3 & 4,5 ^ 6)} Nor arrays: name [ 2 ] ,name [ 'mine' ]	Here is some of the unsupported syntax No support for '++', '--', '%',';': min( ++ age, -- age,age % 2) ; Nor '|', '&', '^': (sum(2 | 3,3 & 4,5 ^ 6)} Nor arrays: name [ 2 ] ,name [ 'mine' ]

Voorbeelden maatwerk (bijv.uitbreiding {INSERTANS:xxx})

Aanhef

Gebruik de if () functie om voorwaardelijk te kiezen of 'Mr.' wordt weergegeven of 'Mrs.'.

The syntaxis is if(test,do_if_true,do_if_false).

#	Code	Vraag	Type
1	geslacht	What is your gender?	Gender
2	voorbeeld1	Dear {if (gender == 'M', 'Mr.', 'Mrs.')} Smith, ...	Lange vrije tekst

Zoals hier kan worden opgemerkt, zijn "Mr" en "Mrs" afgestemd op wat de deelnemer als antwoord op vraag "geslacht" selecteert.

Aanhef in e-mail uitnodiging

U kunt het bovenstaande voorbeeld in de uitnodiging gebruiken met behulp van attributen uit de token-tabel. Gebruik de if-functie om te kiezen of 'Mr.' of 'Mrs.' in de tekst van de e-mail moet worden gebruikt.

De syntaxis is "if(test,do_if_true,do_if_false)".

#	attribute	value
1	Last name	Smith
2	Email address	test@test.com
3	ATTRIBUTE_2	M

Tekst in uitnodiging:

Dear {if(ATTRIBUTE_2=='M','Mr','Mrs')} {LASTNAME},

you have been invited to participate in a survey:

https:/...

email View:

Voorbeelden berekening /beoordeling

Berekenen beoordelingswaarden bij uitvoering en opslaan van de resultaten

This example uses all of EM's features, including Relevance, Tailoring, and the Equation question type.

It also shows that all of them are JavaScript-enabled, so if you have these features on a page, it will dynamically change as people set and change their answers.

#	Code	Question	Type	Relevance
1	numKids	How many children do you have?	Numerical input	1
2	kid1	How old is your first child?	Numerical input	numKids >= 1
3	kid2	How old is your second child?	Numerical input	numKids >= 2
4	kid3	How old is your third child?	Numerical input	numKids >= 3
5	kid4	How old is your fourth child?	Numerical input	numKids >= 4
6	sumKidAges	{sum(kid1.NAOK,kid2.NAOK,kid3.NAOK,kid4.NAOK)}	Equation	1
7	kidSummary	You said that you have {numKids}. {if(numKids==1,'child','children')}. {if(numKids>1,implode(' ','The sum of ages of your first ',min(numKids,4),' kids is ',sumKidAges,'.'),' ')}	Text display	1

To download this example, please click on the following link: Assessments_survey_example.

You may find below screenshots of representative questions. As you can see, EM syntax-highlights all fields that might contain tailoring. Here, you see examples of syntax-highlighting Relevance, the Equation question type, and substitutions within a question. You can also use substitutions within Help, Group header display, Welcome message, and End message.

In the next example, since the relevance is {numKids >= 2), the question will only be visible if the respondent reports that she has at least two children.

Below, you may observe that each variable has the .NAOK suffix attached to it. This is because of how EM supports cascading relevance. If you did not have .NAOK, then the sum would only be computed if the person said she has 4 children (e.g., if all of the variables are relevant). The usage of .NAOK means that we want to compute the sum even if all or some of the variables are irrelevant (e.g., "Not Applicable" (NA) is alright (OK)).

However, the .NAOK attribute only affects whether variables are passed into EM. If the respondent initially says she has 3 children, and enters ages for each, then changes her mind and says she has 2, we don't want to see the sum of the 3 entered values - since the third child is "not applicable" in our case anymore:

Each separate Expression is color coded with a tan background. As you can see, there are three separate Expressions here. The last one contains a message that is conditionally shown only if the person has more than one child.

Now, here are screenshots of the survey in action.

When you first visit the page, you see this. Note that is says "You have 0 children" instead of "You have 0 child".

If I change the value for number of children to 1, the display instantly changes to this, even though it is on the same page:

Merk op dat de grammatica correct is: "You have 1 'child' ".

Nu verander ik de waarde voor het aantal kinderen in 3 en het resultaat wordt direct:

Let op het voorwaardelijke bericht onderaan: "The sum of ages of your first 3 kids is 0.".

Now I'll enter ages for my imaginary children, and I get this display, summing up their ages:

Again, the score and display updates instantly as I enter the values, so you can use this to show a running total of an Assessment Score.

Now, I change the value for the number of children to 2. The display has changed to this:

Notice that although I had entered a value of 5.5 for the third child, the report now only sums the values of my first 2 children.

The reason for this is that the 3rd value is now irrelevant, and irrelevant values are actively ignored by EM.

If I were to change the number of kids back to 3, I would see the value of 5.5 I entered again. So, I don't lose any information I enter on the page.

However, if I navigate to the Next or Previous page, all irrelevant values will be NULLed out in the session and in the database. So, if I were to keep the value at 2, go to the next page, and then come back and state that I actually have 3 kids, I would no longer see the age of 5.5.

Enter data and see a dynamically changing report of what was entered on the same page

This example presents the Tailoring process within LimeSurvey.

To download this example, click on the following link: Dynamic changes survey example.

Here is what the page looks like initially. You only see the question asking what city you live in:

Once you start to enter an answer, the tailoring process is also starting:

As you enter answers, the table at the bottom of the page is updated to show the answer codes and values of your responses.

Voorbeeld gebruikelijke foutopsporing

Geneste if-statements (Conditionele logica)

EM supports the function "if(test,do_if_true,do_if_false)" so that you can perform conditional logic or tailoring. This function can be nested to do the equivalent of "if { } else if { } else {  }". EM will let you know if the parentheses are not balanced (e.g., you are missing a closing right parenthesis), or if you have any extra right parentheses. You should try to count the parentheses as you compose long nested if statements, save it, check for syntax errors, and fix them if any are found. Let's check together the below example.

The group of questions used below can be accessed from here: Tailoring survey example.lsg

First, with nothing entered, you just see "Hello."

If you enter a name, it says, "Hello {name}."

If you enter an age, you get a tailored message, depending upon whether you are a pre-school-age child or not:

School aged, teenager, or adult. Here is a  teenager who wants to be anonymous:

Here is the logic file of the group. As you can see in the "if-based" question, there are nested if statements based upon the person's age.

When you are originally editing this question, it is likely that at some point, you will have the wrong number of parentheses. Here's what happens if you have too few:

If you hover over the word "if", which is surrounded by a red box, it says "Parentheses not balanced". In this case, there should be four closing parentheses after "already an adult!", but there are only three.

If, on the other hand, you have an extra right parenthesis, it will be surrounded by a red box, like this:

Wanneer je de vraag bewerkt, ziet de vraag er als volgt uit: