Incorporated review feedback

- Combined functionality with the ExternalAnswerValueSetResolver
- Renamed various functions and arguments for improved clarity
- Moved filter handling out of the adapter and into the textChangedListener
- Moved resolver to the viewmodel

Author: dilys-l

catalog/src/main/assets/component_auto_complete.json

@@ -93,6 +93,27 @@
           }
         }
       ]
+    },
+    {
+      "extension": [
+        {
+          "url": "http://hl7.org/fhir/StructureDefinition/questionnaire-itemControl",
+          "valueCodeableConcept": {
+            "coding": [
+              {
+                "system": "http://hl7.org/fhir/questionnaire-item-control",
+                "code": "autocomplete"
+              }
+            ]
+          }
+        }
+      ],
+      "linkId": "2",
+      "text": "Procedure",
+      "type": "choice",
+      "required": true,
+      "repeats": false,
+      "answerValueSet": "https://my.url/fhir/ValueSet/my-valueset"
     }
   ]
 }

catalog/src/main/java/com/google/android/fhir/catalog/CatalogApplication.kt

@@ -21,15 +21,15 @@ import ca.uhn.fhir.context.FhirContext
 import com.google.android.fhir.FhirEngine
 import com.google.android.fhir.FhirEngineConfiguration
 import com.google.android.fhir.FhirEngineProvider
-import com.google.android.fhir.datacapture.CustomCallback.AutoCompleteCallback
-import com.google.android.fhir.datacapture.CustomCallbackType
 import com.google.android.fhir.datacapture.DataCaptureConfig
-import com.google.android.fhir.datacapture.views.factories.AutoCompleteViewAnswerOption
+import com.google.android.fhir.datacapture.ExternalAnswerValueSetResolver
 import com.google.android.fhir.search.search
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.delay
 import kotlinx.coroutines.launch
 import org.hl7.fhir.r4.model.Bundle
+import org.hl7.fhir.r4.model.Coding
 
 class CatalogApplication : Application(), DataCaptureConfig.Provider {
   // Only initiate the FhirEngine when used for the first time, not when the app is created.
@@ -47,15 +47,26 @@ class CatalogApplication : Application(), DataCaptureConfig.Provider {
         xFhirQueryResolver = { fhirEngine.search(it).map { it.resource } },
         questionnaireItemViewHolderFactoryMatchersProviderFactory =
           ContribQuestionnaireItemViewHolderFactoryMatchersProviderFactory,
-        callbacks = mapOf(Pair(CustomCallbackType.AUTO_COMPLETE, AutoCompleteCallback(
-          callback = { query ->
-            run {
-              listOf(AutoCompleteViewAnswerOption("a", "Type 2 Diabetes Mellitus"),
-                AutoCompleteViewAnswerOption("b", "Test")
+        valueSetResolverExternal =
+          object : ExternalAnswerValueSetResolver {
+            override suspend fun resolve(uri: String, query: String?): List<Coding> {
+              delay(1000)
+              // Here we can call out to our FHIR terminology server with the provided uri and query
+              if (uri == "https://my.url/fhir/ValueSet/my-valueset" && !query.isNullOrBlank()) {
+                return listOf(
+                  Coding().apply {
+                    code = "a"
+                    display = "Custom response A"
+                  },
+                  Coding().apply {
+                    code = "b"
+                    display = "Custom response B"
+                  },
                 )
+              }
+              return emptyList()
             }
-          }
-        )))
+          },
       )
 
     CoroutineScope(Dispatchers.IO).launch {

datacapture/src/main/java/com/google/android/fhir/datacapture/DataCaptureConfig.kt

@@ -56,12 +56,6 @@ data class DataCaptureConfig(
   var questionnaireItemViewHolderFactoryMatchersProviderFactory:
     QuestionnaireItemViewHolderFactoryMatchersProviderFactory? =
     null,
-
-  /**
-   * A [CustomCallback] may be set by the client to override the behaviour of an existing component
-   * in the sdc.
-   */
-  var callback: CustomCallback<*>? = null,
 ) {
 
   /**
@@ -80,12 +74,18 @@ data class DataCaptureConfig(
  * allows the library to render answer options to `choice` and `open-choice` type questions more
  * dynamically.
  *
+ * Optional query parameter can be used to accept the search string from user input for server-side
+ * filtering.
+ *
  * NOTE: The result of the resolution may be cached to improve performance. In other words, the
  * resolver may be called only once after which the same answer value set may be used multiple times
  * in the UI to populate answer options.
+ *
+ * @param uri The uri used to identify the questionnaire item
+ * @param query The text input from the user
  */
 interface ExternalAnswerValueSetResolver {
-  suspend fun resolve(uri: String): List<Coding>
+  suspend fun resolve(uri: String, query: String?): List<Coding>
 }
 
 /**

datacapture/src/main/java/com/google/android/fhir/datacapture/QuestionnaireEditAdapter.kt

@@ -391,5 +391,3 @@ internal object DiffCallbacks {
       }
     }
 }
-
-typealias CustomCallback<T> = (String, String) -> List<T>

datacapture/src/main/java/com/google/android/fhir/datacapture/QuestionnaireViewModel.kt

@@ -76,6 +76,7 @@ import kotlinx.coroutines.flow.stateIn
 import kotlinx.coroutines.flow.update
 import kotlinx.coroutines.flow.withIndex
 import kotlinx.coroutines.launch
+import org.hl7.fhir.r4.model.Coding
 import org.hl7.fhir.r4.model.DateTimeType
 import org.hl7.fhir.r4.model.Questionnaire
 import org.hl7.fhir.r4.model.Questionnaire.QuestionnaireItemComponent
@@ -96,10 +97,6 @@ internal class QuestionnaireViewModel(application: Application, state: SavedStat
     DataCapture.getConfiguration(application).valueSetResolverExternal
   }
 
-  private val callback: CustomCallback<*>? by lazy {
-    DataCapture.getConfiguration(application).callback
-  }
-
   /** The current questionnaire as questions are being answered. */
   internal val questionnaire: Questionnaire
 
@@ -393,6 +390,23 @@ internal class QuestionnaireViewModel(application: Application, state: SavedStat
       modificationCount.update { it + 1 }
     }
 
+  /**
+   * Function to dynamically resolve answer options for the AutoComplete component using
+   * [ExternalAnswerValueSetResolver.resolve]
+   */
+  private val autoCompleteAnswerOptionResolver: (String, String?, (List<Coding>) -> Unit) -> Unit =
+    { query, answerValueSet, callback ->
+      viewModelScope.launch {
+        val response =
+          if (externalValueSetResolver != null && answerValueSet != null) {
+            externalValueSetResolver!!.resolve(query, answerValueSet)
+          } else {
+            emptyList()
+          }
+        callback(response)
+      }
+    }
+
   private val expressionEvaluator: ExpressionEvaluator =
     ExpressionEvaluator(
       questionnaire,
@@ -954,6 +968,7 @@ internal class QuestionnaireViewModel(application: Application, state: SavedStat
             validationResult = validationResult,
             answersChangedCallback = answersChangedCallback,
             enabledAnswerOptions = enabledQuestionnaireAnswerOptions,
+            autoCompleteAnswerOptionResolver = autoCompleteAnswerOptionResolver,
             minAnswerValue =
               questionnaireItem.minValueCqfCalculatedValueExpression?.let {
                 expressionEvaluator.evaluateExpressionValue(
@@ -989,7 +1004,7 @@ internal class QuestionnaireViewModel(application: Application, state: SavedStat
               ),
             isHelpCardOpen = isHelpCard && isHelpCardOpen,
             helpCardStateChangedCallback = helpCardStateChangedCallback,
-            callback = callback,
+            //            suggestions = suggestions,
           ),
         )
       add(question)

datacapture/src/main/java/com/google/android/fhir/datacapture/expressions/EnabledAnswerOptionsEvaluator.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2022-2024 Google LLC
+ * Copyright 2022-2025 Google LLC
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -179,7 +179,7 @@ internal class EnabledAnswerOptionsEvaluator(
           }
       } else {
         // Ask the client to provide the answers from an external expanded Valueset.
-        externalValueSetResolver?.resolve(uri)?.map { coding ->
+        externalValueSetResolver?.resolve(uri, null)?.map { coding ->
           Questionnaire.QuestionnaireItemAnswerOptionComponent(coding.copy())
         }
       }

datacapture/src/main/java/com/google/android/fhir/datacapture/views/QuestionnaireViewItem.kt

@@ -19,7 +19,6 @@ package com.google.android.fhir.datacapture.views
 import android.content.Context
 import android.text.Spanned
 import androidx.recyclerview.widget.RecyclerView
-import com.google.android.fhir.datacapture.CustomCallback
 import com.google.android.fhir.datacapture.R
 import com.google.android.fhir.datacapture.extensions.displayString
 import com.google.android.fhir.datacapture.extensions.isHelpCode
@@ -31,6 +30,7 @@ import com.google.android.fhir.datacapture.validation.NotValidated
 import com.google.android.fhir.datacapture.validation.Valid
 import com.google.android.fhir.datacapture.validation.ValidationResult
 import com.google.android.fhir.datacapture.views.factories.QuestionnaireItemViewHolder
+import org.hl7.fhir.r4.model.Coding
 import org.hl7.fhir.r4.model.Questionnaire
 import org.hl7.fhir.r4.model.Questionnaire.QuestionnaireItemComponent
 import org.hl7.fhir.r4.model.QuestionnaireResponse
@@ -94,7 +94,9 @@ data class QuestionnaireViewItem(
   val helpCardStateChangedCallback: (Boolean, QuestionnaireResponseItemComponent) -> Unit =
     { _, _ ->
     },
-  val callback: CustomCallback<*>? = null,
+  internal val autoCompleteAnswerOptionResolver: (String, String?, (List<Coding>) -> Unit) -> Unit =
+    { _, _, _ ->
+    },
 ) {
 
   fun getQuestionnaireResponseItem(): QuestionnaireResponseItemComponent = questionnaireResponseItem

datacapture/src/main/java/com/google/android/fhir/datacapture/views/factories/AutoCompleteViewHolderFactory.kt

@@ -28,8 +28,8 @@ import androidx.appcompat.app.AppCompatActivity
 import androidx.core.view.children
 import androidx.core.view.get
 import androidx.core.view.isEmpty
+import androidx.core.widget.addTextChangedListener
 import androidx.lifecycle.lifecycleScope
-import com.google.android.fhir.datacapture.CustomCallback
 import com.google.android.fhir.datacapture.R
 import com.google.android.fhir.datacapture.extensions.displayString
 import com.google.android.fhir.datacapture.extensions.identifierString
@@ -58,14 +58,11 @@ internal object AutoCompleteViewHolderFactory :
       private lateinit var autoCompleteTextView: MaterialAutoCompleteTextView
       private lateinit var chipContainer: ChipGroup
       private lateinit var textInputLayout: TextInputLayout
-      private lateinit var adapter: ArrayAdapter<AutoCompleteViewAnswerOption>
+      private lateinit var adapter: AutoCompleteArrayAdapter
 
       private val canHaveMultipleAnswers
         get() = questionnaireViewItem.questionnaireItem.repeats
 
-      private val callback: CustomCallback<*>?
-        get() = questionnaireViewItem.callback
-
       override lateinit var questionnaireViewItem: QuestionnaireViewItem
       private lateinit var errorTextView: TextView
 
@@ -82,30 +79,50 @@ internal object AutoCompleteViewHolderFactory :
       override fun bind(questionnaireViewItem: QuestionnaireViewItem) {
         header.bind(questionnaireViewItem)
         header.showRequiredOrOptionalTextInHeaderView(questionnaireViewItem)
-        val suggestions = mutableListOf<AutoCompleteViewAnswerOption>()
         val answerOptionValues =
           questionnaireViewItem.enabledAnswerOptions.map {
             AutoCompleteViewAnswerOption(
               answerId = it.value.identifierString(header.context),
               answerDisplay = it.value.displayString(header.context),
             )
           }
-        suggestions.addAll(answerOptionValues)
         adapter =
           AutoCompleteArrayAdapter(
             context = header.context,
             resource = R.layout.drop_down_list_item,
             textViewResourceId = R.id.answer_option_textview,
             objects = answerOptionValues,
-            callback = callback,
-            answerValueSet = questionnaireViewItem.questionnaireItem.answerValueSet,
           )
         autoCompleteTextView.setAdapter(adapter)
         // Remove chips if any from the last bindView call on this VH.
         chipContainer.removeAllViews()
         presetValuesIfAny()
 
         displayValidationResult(questionnaireViewItem.validationResult)
+
+        val serverSideFiltering =
+          questionnaireViewItem.questionnaireItem.answerValueSet != null &&
+            answerOptionValues.isEmpty()
+
+        autoCompleteTextView.addTextChangedListener { text ->
+          if (serverSideFiltering) {
+            questionnaireViewItem.autoCompleteAnswerOptionResolver(
+              text.toString(),
+              questionnaireViewItem.questionnaireItem.answerValueSet,
+            ) { response ->
+              val items =
+                response.map {
+                  AutoCompleteViewAnswerOption(
+                    answerId = it.code,
+                    answerDisplay = it.display,
+                  )
+                }
+              adapter.updateData(items)
+            }
+          } else {
+            adapter.clientSideFilter(text.toString())
+          }
+        }
       }
 
       override fun setReadOnly(isReadOnly: Boolean) {
@@ -272,7 +289,7 @@ internal object AutoCompleteViewHolderFactory :
  * An answer option that would show up as a dropdown item in an [AutoCompleteViewHolderFactory]
  * textview
  */
-data class AutoCompleteViewAnswerOption(val answerId: String, val answerDisplay: String) {
+internal data class AutoCompleteViewAnswerOption(val answerId: String, val answerDisplay: String) {
   override fun toString(): String {
     return this.answerDisplay
   }
@@ -283,8 +300,6 @@ internal class AutoCompleteArrayAdapter(
   val resource: Int,
   val textViewResourceId: Int,
   private val objects: List<AutoCompleteViewAnswerOption>,
-  private val callback: CustomCallback<*>? = null,
-  private val answerValueSet: String? = null,
 ) : ArrayAdapter<AutoCompleteViewAnswerOption>(context, resource, textViewResourceId, objects) {
 
   private var items = listOf<AutoCompleteViewAnswerOption>()
@@ -303,6 +318,11 @@ internal class AutoCompleteArrayAdapter(
     notifyDataSetChanged()
   }
 
+  fun clientSideFilter(query: String) {
+    items = objects.filter { it.answerDisplay.contains(query, ignoreCase = true) }
+    notifyDataSetChanged()
+  }
+
   override fun getDropDownView(position: Int, convertView: View?, parent: ViewGroup): View {
     return getView(position, convertView, parent)
   }
@@ -312,21 +332,12 @@ internal class AutoCompleteArrayAdapter(
   @Suppress("UNCHECKED_CAST")
   override fun getFilter(): Filter {
     return object : Filter() {
+
       override fun performFiltering(constraint: CharSequence?): FilterResults {
-        val query = (constraint?.toString() ?: "").trim()
-        val filteredResults: List<AutoCompleteViewAnswerOption> =
-          if (callback != null && answerValueSet != null && objects.isEmpty()) {
-            (callback as? CustomCallback<AutoCompleteViewAnswerOption>)?.invoke(
-              query,
-              answerValueSet,
-            )
-              ?: emptyList()
-          } else {
-            objects.filter { it.answerDisplay.contains(query, ignoreCase = true) }
-          }
+        // Prevent default filtering behaviour
         return FilterResults().apply {
-          values = filteredResults
-          count = filteredResults.size
+          values = items
+          count = items.size
         }
       }
 

datacapture/src/test/java/com/google/android/fhir/datacapture/QuestionnaireViewModelTest.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2023-2024 Google LLC
+ * Copyright 2023-2025 Google LLC
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -5022,7 +5022,7 @@ class QuestionnaireViewModelTest {
       DataCaptureConfig(
         valueSetResolverExternal =
           object : ExternalAnswerValueSetResolver {
-            override suspend fun resolve(uri: String): List<Coding> {
+            override suspend fun resolve(uri: String, query: String?): List<Coding> {
               return if (uri == CODE_SYSTEM_YES_NO) {
                 listOf(
                   Coding().apply {