Conditional questions: base implementation plus support for radio and dropdown triggers

docs/DataStructure.md

@@ -1,5 +1,5 @@
 <!--
-  - SPDX-FileCopyrightText: 2021 Nextcloud GmbH and Nextcloud contributors
+  - SPDX-FileCopyrightText: 2021-2026 Nextcloud GmbH and Nextcloud contributors
   - SPDX-License-Identifier: AGPL-3.0-only
 -->
 
@@ -240,6 +240,7 @@ Currently supported Question-Types are:
 | `linearscale`     | A linear or Likert scale question where you choose an option that best fits your opinion                                                                                          |
 | `color`           | A color answer, hex string representation (e. g. `#123456`)                                                                                                                       |
 | `ranking`         | Using pre-defined options, the user ranks them from most to least preferred. Needs at least one option available. Answers are stored in ranked order (one answer row per option). |
+| `conditional`     | A conditional branching question with a trigger question and multiple branches containing subquestions                                                                            |
 
 ## Extra Settings
 
@@ -282,3 +283,126 @@ Supported option types and their intended usage.
 | `column` | Represents a column header when rendering options in a grid-style question.                |
 
 `row` and `column` option types are primarily used together with `grid` question types to build a two-dimensional selection matrix. `choice` is the default for normal option lists.
+| `triggerType` | `conditional` | string | [See trigger types](#conditional-trigger-types) | The type of trigger question (dropdown, multiple_unique, etc.) |
+| `branches` | `conditional` | Array | Array of [Branch objects](#branch-object) | The branches with conditions and subquestions |
+
+## Conditional Questions
+
+Conditional questions enable branching logic in forms. A trigger question determines which branch of subquestions appears based on the respondent's answer.
+
+### Question Properties for Subquestions
+
+Subquestions (questions belonging to a conditional question's branch) have additional properties:
+
+| Property         | Type    | Description                                                            |
+| ---------------- | ------- | ---------------------------------------------------------------------- |
+| parentQuestionId | Integer | The ID of the parent conditional question (null for regular questions) |
+| branchId         | String  | The ID of the branch this subquestion belongs to                       |
+
+### Conditional Trigger Types
+
+Supported trigger types for conditional questions:
+
+| Trigger Type      | Condition Types                                                             | Description                                       |
+| ----------------- | --------------------------------------------------------------------------- | ------------------------------------------------- |
+| `multiple_unique` | `option_selected`                                                           | Radio buttons - the selected option               |
+| `dropdown`        | `option_selected`                                                           | Dropdown - the selected option                    |
+
+A branch is shown when any of its conditions matches. Several branches can be shown at once.
+
+### Branch Object
+
+A branch defines conditions and subquestions that appear when those conditions are met.
+
+| Property     | Type                                     | Description                                    |
+| ------------ | ---------------------------------------- | ---------------------------------------------- |
+| id           | String                                   | Unique identifier for the branch               |
+| conditions   | Array of [Conditions](#condition-object) | Conditions that must be met to show the branch |
+| subQuestions | Array of [Questions](#question)          | Questions shown when conditions are met        |
+
+```json
+{
+	"id": "branch-1705587600000",
+	"conditions": [{ "type": "option_selected", "optionId": 42 }],
+	"subQuestions": [
+		{
+			"id": 101,
+			"formId": 3,
+			"order": 1,
+			"type": "short",
+			"text": "Please provide details",
+			"parentQuestionId": 100,
+			"branchId": "branch-1705587600000"
+		}
+	]
+}
+```
+
+### Condition Object
+
+Conditions determine when a branch is activated. The structure depends on the trigger type.
+
+#### option_selected (for dropdown, multiple_unique)
+
+```json
+{ "type": "option_selected", "optionId": 42 }
+```
+
+### Conditional Question Example
+
+A complete conditional question structure:
+
+```json
+{
+	"id": 100,
+	"formId": 3,
+	"order": 1,
+	"type": "conditional",
+	"isRequired": true,
+	"text": "Do you have any dietary restrictions?",
+	"options": [
+		{ "id": 42, "questionId": 100, "order": 1, "text": "Yes" },
+		{ "id": 43, "questionId": 100, "order": 2, "text": "No" }
+	],
+	"extraSettings": {
+		"triggerType": "dropdown",
+		"branches": [
+			{
+				"id": "branch-yes",
+				"conditions": [{ "type": "option_selected", "optionId": 42 }],
+				"subQuestions": [
+					{
+						"id": 101,
+						"formId": 3,
+						"order": 1,
+						"type": "long",
+						"text": "Please describe your dietary restrictions",
+						"parentQuestionId": 100,
+						"branchId": "branch-yes"
+					}
+				]
+			}
+		]
+	}
+}
+```
+
+### Conditional Answer Structure
+
+When submitting or storing conditional question answers, the structure differs from regular questions:
+
+```json
+{
+	"100": {
+		"trigger": ["42"],
+		"subQuestions": {
+			"101": ["Vegetarian, no nuts"]
+		}
+	}
+}
+```
+
+| Property     | Type                        | Description                                         |
+| ------------ | --------------------------- | --------------------------------------------------- |
+| trigger      | Array of strings            | Answer values for the trigger question              |
+| subQuestions | Object (questionId → Array) | Map of subquestion IDs to their answer value arrays |

lib/Analytics/AnalyticsDatasource.php

@@ -101,8 +101,8 @@ public function readData($option): array {
 
 		$formId = $option['formId'];
 
-		$questions = $this->formsService->getQuestions($formId);
-		foreach ($questions as $question) {
+		// Answers of subquestions are counted with the text of their subquestion
+		foreach (FormsService::flattenQuestions($this->formsService->getQuestions($formId)) as $question) {
 			$questionMap[$question['id']] = $question['text'];
 		}
 

lib/Constants.php

@@ -1,7 +1,7 @@
 <?php
 
 /**
- * SPDX-FileCopyrightText: 2021 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-FileCopyrightText: 2021-2026 Nextcloud GmbH and Nextcloud contributors
  * SPDX-License-Identifier: AGPL-3.0-or-later
  */
 
@@ -101,6 +101,7 @@ class Constants {
 
 	// Available AnswerTypes
 	public const ANSWER_TYPE_COLOR = 'color';
+	public const ANSWER_TYPE_CONDITIONAL = 'conditional';
 	public const ANSWER_TYPE_DATE = 'date';
 	public const ANSWER_TYPE_DATETIME = 'datetime';
 	public const ANSWER_TYPE_DROPDOWN = 'dropdown';
@@ -121,6 +122,7 @@ class Constants {
 	// All AnswerTypes
 	public const ANSWER_TYPES = [
 		self::ANSWER_TYPE_COLOR,
+		self::ANSWER_TYPE_CONDITIONAL,
 		self::ANSWER_TYPE_DATE,
 		self::ANSWER_TYPE_DATETIME,
 		self::ANSWER_TYPE_DROPDOWN,
@@ -239,6 +241,35 @@ class Constants {
 		self::ANSWER_GRID_TYPE_RADIO,
 	];
 
+	/**
+	 * Extra settings for conditional questions
+	 * - triggerType: The question type used for the trigger (e.g., 'multiple_unique', 'dropdown', 'short')
+	 * - branches: Array of branch definitions, each containing:
+	 *   - id: Unique branch identifier
+	 *   - conditions: Array of condition objects defining when this branch is active
+	 *     For predefined types: [{ optionId: number }]
+	 *     For text types: [{ type: 'string_equals'|'string_contains'|'regex', value: string }]
+	 *     For numeric/scale: [{ type: 'value_equals'|'value_range', value: number, min?: number, max?: number }]
+	 */
+	public const EXTRA_SETTINGS_CONDITIONAL = [
+		'triggerType' => ['string'],
+		'branches' => ['array'],
+	];
+
+	/**
+	 * Condition types for conditional questions
+	 */
+	public const CONDITION_TYPE_OPTION_SELECTED = 'option_selected';
+
+	/**
+	 * Trigger types allowed for conditional questions
+	 * Maps each trigger type to its supported condition types
+	 */
+	public const CONDITIONAL_TRIGGER_TYPES = [
+		self::ANSWER_TYPE_MULTIPLEUNIQUE => [self::CONDITION_TYPE_OPTION_SELECTED],
+		self::ANSWER_TYPE_DROPDOWN => [self::CONDITION_TYPE_OPTION_SELECTED],
+	];
+
 	/**
 	 * !! Keep in sync with src/mixins/ShareTypes.js !!
 	 */