@i4mi/fhir_questionnaire v0.2.1

I4MI Questionnaire Data

QuestionnaireData is a class that facilitates the rendering and handling of FHIR Questionnaires in TypeScript / Javascript applications.

• ❗️ Please be aware that this is currently work in progress.
• ❗️ Not all features of FHIR Questionnaire are supported, and some functionality is not yet documented.
• ❗️ Although we do our best in carefully developping and testing the class, there are probably minor and major bugs. If you find one, let us know and raise an issue on github).
• ❗️ We do not recommend using this for production projects.
• ❗️ QuestionnaireData is based on the FHIR R4 (4.0.1) version of the Questionnaire resource.

See also the documentation of the FHIR Questionnaire and FHIR QuestionnaireResponse resources.

Demo App

There is a small demo app written in Vue.js, that demonstrates the use of the library with different FHIR Questionnaires.

Basic use

Install

Before you can use this package in your project, you need to install it, using npm. Point your terminal to the root directory of your project (where also package.jsonis located) and enter the following command.

npm install @i4mi/fhir_questionnaire

Wait for the install to complete and you are ready to set up QuestionnaireData.

Setup

For every questionnaire you want to handle, you need to initialize a QuestionnaireData instance, providing the FHIR questionnaire resource as a JSON object, and at least one shorthand for an available language:

import {QuestionnaireData} from '@i4mi/fhir_questionnaire';

// ... other code

const qData = new QuestionnaireData(fhirQuestionnaire, ['en']);

External ValueSets

The constructor has also the possibility to hand over ValueSet resources, that are referenced in the Questionnaire (as answerValuesets for questions of type choice). As a matter of fact, it is necessary to provide ValueSets that are not contained in the Questionnaire, since QuestionnaireData does not fetch linked ValueSets by itself. This would be the third, optional parameter of the constructor.
Please note: This feature is not thoroughly tested yet and has a high probability of bugs or unexpected behaviour.

Passing on items and hiddenItems

The fourth and fifth optional parameter of the constructor are to pass on IQuestion items and hidden items. This is useful when using in a React enviroment with redux, but can probably be ignored in other setups.

Rendering of the questions

You can then use the QuestionnaireData instance to get the items and render them. You have to implement the rendering for every Question type the questionnaire you're using has, since a "choice" question needs to be rendered differently than a "free text" question. In a Vue.js app, this could look something like that (please mind that this is a very basic example and does not take into account more complicated use cases like nested questions):

<div v-for="question in qData.getQuestions()"
     :key="question.id">
  <div v-if="question.isEnabled"
       :class="'question-' + question.type + (question.isInvalid ? ' invalid' : '')">
    <h2>
      {{ question.label[lang] }}
    </h2>
    <!-- CHOICE question -->
    <ul v-if="question.type === 'choice'">
      <li v-for="answer in question.answerOptions"
          :key="question.id + '-' + answer.code"
          @click="qData.updateQuestionAnswers(question, answer)">
        <input :type="question.allowsMultipleAnswers ? 'checkbox' : 'radio'"
               :checked="qData.isAnswerOptionSelected(question, answer)"
               :name="question.id"
               :id="answer.code.toString()" />
        <label for="answer.code.toString()">
          {{ answer.answer[lang] }}
        </label>
      </li>
    </ul>
    <!-- implement other question types-->
    ...
  </div>
</div>

Retrieving the QuestionnaireResponse

The QuestionnaireResponse can be retrieved with the getQuestionnaireResponse() method. You need to provide a language shorthand, which must be one of the shorthands you provided as available language in the constructor when setting up the QuestionnaireData instance. getQuestionnaireResponse() checks the answers for validity, and throws an error if one question has not a valid answer (the first invalid question is then marked with isInvalid=true, so you can give this feedback to the user). For this reason, it is recommended to wrap this in a try/catch block. For detailed options of getQuestionnaireResponse(), see below.

try {
  const response = qData.getQuestionnaireResponse('en');
} catch(e) {
  console.warn('Something ain\'t right:', e);
}

Interfaces

IQuestion

Every Questionnaire item is converted to a IQuestion, which makes handling it easier. It has the following properties.
Properties are marked as followed:
🎨 = important for rendering ⚙️ = mostly for internal use in QuestionnareData

• 🎨 type (QuestionnaireItemType from @i4mi/fhir_r4): The type of the question. Important for rendering.
• 🎨 label ({language: string: string): The label / question of the string, with strings in every available language (with fallback strings if the Questionnaire does not have the language available)
• 🎨 prefix (string): The prefix of the question, often the number of the question in the questionnaire
• 🎨 answerOptions (IAnswerOption[], see below): The answer options, for example for choice questions.
• 🎨 allowsMultipleAnswers (boolean): Describes if multiple answers are allowed (not applicable for every type of question)
• 🎨 isEnabled (boolean): Describes if a question is enabled and should be displayed to the user. This is for example used for questions that are depending on other questions and are only enabled when the other question is answered in a certain way.
• 🎨 readOnly: (boolean): Describes if a question is read only and should not be changed by the user. You should take this into account when rendering your questions.
• 🎨 subItems? (IQuestion[]): A question of type GROUP, but also other question, can have nested subquestions (which again, can have subquestions).
• 🎨 isInvalid (boolean): Indicates if the answer(s) to a question are invalid. This is not updated in real time, but on getQuestionaireResponse()
• 🎨/⚙️ options (IQuestionOptions, see below): Options for this item.
• ⚙️ selectedAnswers (QuestionnaireResponseItemAnswer[], see below): Array of none to multiple answers the user has selected / given to the question.
• ⚙️ required (boolean): Describes if the question needs to be answered.
• ⚙️ initial (QuestionnaireItemInitial[] from @i4mi/fhir_r4): Initial value of the item.
• ⚙️ id (string): Corresponds to the linkId of the Questionnaire item.
• ⚙️ dependingQuestionsEnableBehaviour ('ALL' or 'ANY'): Describes if all of the criteria below must be fulfilled to enable a depending question, or if one criteria is enough.
• ⚙️ dependingQuestions: Links depending questions to this question. Depending questions are activated if the criteria are matched.

IAnswerOption

Answer options conform to this interface:

• answer ({language: string: string}): The actual answer string, in possible different languages.
• code (QuestionnaireResponseItemAnswer from @i4mi/fhir_r4): The actual coding of the answer
• disableOtherAnswers: Determines which other answers are unselected if this answer is selected (in multiple choice questions).

IQuestionOptions

The options object can provice additional information for a question. Often, these are mostly used for internal usage. All of the options are optional.

• controlTypes (ItemControlType[]): Describes the UI control types relevant for a question (see the Questionnaire Item Control Valueset).
• min (number): The minimal value accepted for the item (this is for rendering, not taken into consideration when validating the answers!).
• max (number): The maximum value accepted for the item (this is for rendering, not taken into consideration when validating the answers!). Can be defined in the Questionnaire using the maxValue extension.
• sliderStep (number): Describes the step for a slider, if provided as SliderStepValue extension. If the controlType of a question is slider, this should be considered when rendering the question.
• unit (Coding): A possible unit as provided by the QuestionnaireItem Unit extension
• format (string): Describes the desired format of the answer, as provided by the QuestionnaireItem format extension. This is to be meant for displaying in the GUI and has no effect on the answer validation in QuestionnaireData.
• initialExpression (string): Mostly for internal use. Used to save the FHIRPath expression for calculating the items initial value for populating the Questionnaire. See also populateAnswers().
• calculatedExpression (string): Mostly for internal use. Used to save the calculated expression (FHIRPath) for calculating an items value. For details, see the Working with calculated expressions chapter.
• controlType (ItemControlType): DEPRECATED. Describes the UI control type relevant for a question (see the Questionnaire Item Control Valueset). Will be removed in version 1.0.0.

Supported types

Not all types of QuestionnaireItems are currently supported by QuestionnaireData. If you need a type that is currently not supported, you can implement it and make a pull request. If you don't see yourself able to do so, please raise an issue.

• (1) QUANTITY items need an initial value for calculated expressions to work.
• (2) Support of depending questions is different for different operators.
• (3) Support depends on type of the choice items, only for single choice questions.

Methods

serialize(): string

Returns the storeable data of the object as a string, not including the questionnaire. Note for using with React / React Native: When rehydrating with a serialized QuestionnaireData string, you can create a new QuestionnaireData object using the Questionnaire and then call unserialize() on it, passing the serialized string.

• returns: a string representing the QuestionnaireData object without containing the fhir Questionnaire

unserialize(_data): void

Populates the QuestionnaireData object with data from a previously serialized QuestionnaireData Object. This can be either passed on as a string from serialize() or as a JSON object that was created with JSON.stringify() from a QuestionnaireData object.

• parameter _data: The serialized data from a QuestionnaireData as string or JSON
• throws_ An error if the data is passed as a string with no items property (which is used to detect if it is a serialized QuestionnaireData).

resetResponse(): void

Resets the response to the questionnaire.

getQuestions(): IQuestion[]

Returns the questions as an array of IQuestion objects.

• returns: An array of IQuestion objects

updateQuestionAnswers(_question, _answer): void

Updates the selected answer(s) of a question: adds the answer if it's not already selected and removes it, if it was selected. Important when using Vue.js: When you're using Vue.js and are calling this method directly from the template, Vue.js binds it to the vue instance. For QuestionnaireData to work correctly, you have to explicitly bind it to your QuestionnaireData instance like this: :onAnswer="qData.updateQuestionAnswers.bind(qData)", where qData is your QuestionnaireData instance.

• parameter _question: the IQuestion to which the answer belongs
• parameter _answer: the selected / unselected QuestionnaireItemAnswerOption. Important is the code property (it needs to contain a valueString, valueInteger, valueCoding, … ), the answer property must be present, but can be an empty object ({}).

isAnswerOptionSelected(_question, _answer): boolean

Checks if a given IAnswerOption is already selected for a IQuestion.

• parameter _question: the IQuestion to which the answer belongs
• parameter _answer: the IAnswerOption in question
• returns: true, if the given answer is selected, false if not

getQuestionnaireTitle(_language): string | undefined

Returns the questionnaire title in a given language. Falls back to default language of the questionnaire, if the wanted language is not available.

• parameter _language: the language code of the wanted language.
• returns: The title, when available in the requested language, else in the Questionnaires default language (or undefined, if no title is set in the Questionnaire)

getQuestionnaireDescription(_language): string | undefined

Returns the questionnaire description in a given language. Falls back to default language of the questionnaire, if the wanted language is not available.

• parameter _language: the language code of the wanted language.
• returns: The description, when available in the requested language, else in the Questionnaires default language (or undefined, if no description is set in the Questionnaire)

restoreAnswersFromQuestionnaireResponse(_fhirResponse): void

Processes a QuestionnaireResponse and sets its answers to the QuestionnaireData object. The existing answers are overwritten.

• parameter _fhirResponse: a QuestionnaireResponse that matches the Questionnaire
• throws: an error if the QuestionnaireResponse is not matching the Questionnaire

getQuestionnaireResponse(_language,_options?): QuestionnaireResponse

Gets the QuestionnaireResponse resource with all the currently set answers.

• parameter _language: the shorthand for the language the QuestionnaireResponse (eg. 'de' or 'en'), should be in the set of available languages
• parameter _options: Options object that can contain zero, one or many of the following properties:
  • date: the date when the Questionnaire was filled out (current date by default)
  • includeID: boolean that determines if to include FHIR resource ID of a potential previously restored QuestionnaireResponse (default: false)
  • patient: a Reference to the FHIR Patient who filled out the Questionnaire
  • midataExtensions: wether to include extensions that are relevant for MIDATA or not. (default: false)
  • reset: should the questionnaire be reseted after creating the response (default: false)
• throws an error if the QuestionnaireResponse is not valid for the corresponding Questionnaire, e.g. when a required answer is missing (the first invalid IQuestion is marked with isInvalid)
• returns: a QuestionnaireResponse FHIR resource containing all the answers the user gave

getQuestionnaireURLwithVersion(): string

Returns the questionnaire URL with version number in FHIR canonical format.

• returns: a canonical questionnaire URL

isResponseComplete(_onlyRequired?, _markInvalid?): boolean

Checks a QuestionnaireResponse for completeness.

• parameter _onlyRequired: optional parameter, to specify if only questions with the required attribute need to be answered or all questions (default: false)
• parameter _markInvalid: optional parameter, to specify if not completed questions should be updated to be invalid (see isInvalid property) (default: true)
• returns: true if all questions are answered, false if at least one question is not answered

isQuestionComplete(_question, _markInvalid?): boolean

Determines if a question has an answer, when an answer is required. Also checks potential subquestions, if these are activated.

• parameter _question: the question that should be checked
• parameter _markInvalid: optional parameter, indicates if the question (and subquestion) should be marked as invalid if the question is not complete. defaults to true.
• returns TRUE, if the question either does not require an answer, or does require and has at least one answer. If the questions subquestions are activated and not complete, the parent question is also regarded incomplete and thus FALSE is returned.

populateAnswers(_resources, _overWriteExistingAnswers?): void

Populates the questions with initialExpression FHIRPath extensions with data from given resources. The FHIRPath resources need to specify the needed resource type with %type as first node of the FHIRPath expressions (e.g. '%patient.name.given.first()'). You can use more complicated expressions with %type syntax (for example %patient.name.where(use='official').given.first() + ' ' + %patient.name.where(use='official').family.first(). An expression can only be populated from one resource, however a questionnaire can have multiple expression with different resources. When populating an item of type quantity, the result of the expression must be a string with value and unit separated by a space (e.g. 123 cm).

• parameter _resources: an Array of resources used to populate the answers (e.g. Patient resource). Each resource type can only be in the array once.
• parameter _overWriteExistingAnswers: optional parameter, specifies if existing answers should be overwritten (default: false)

findQuestionById(_id, _data): IQuestion | undefined {

Recursively searches for a IQuestion by ID. This is useful if a Questionnaires questions are nested on multiple layers.

• parameter _id: the id of the IQuestion to find
• parameter _data: the (nested) array of IQuestion to search in

Working with calculated expressions

With calculated expressions, you can set the answer to one or multiple items of your questionnaire automatically, depending on the responses given on the responses the user gave to the other elements. You have to specify a FHIRPath-Expression, that can be applied to the QuestionnaireResponse to extract a single value. The questionnaireResponse item is referred to as item in the calculated expression. The first value of the FHIRPath evaluation is then written to the items answer. The expression has to be defined in the calculatedExpression extension. You can see some examples in the Calculated Expressions Questionnaire.

Currently, calculated expressions are only available for items with the hidden-Extension.

Changelog

See CHANGELOG.md