Aggregations API proposal

firebase-firestore/ktx/src/main/kotlin/com/google/firebase/firestore/ktx/Firestore.kt

@@ -18,12 +18,7 @@ import androidx.annotation.Keep
 import com.google.firebase.FirebaseApp
 import com.google.firebase.components.Component
 import com.google.firebase.components.ComponentRegistrar
-import com.google.firebase.firestore.DocumentSnapshot
-import com.google.firebase.firestore.FieldPath
-import com.google.firebase.firestore.FirebaseFirestore
-import com.google.firebase.firestore.FirebaseFirestoreSettings
-import com.google.firebase.firestore.QueryDocumentSnapshot
-import com.google.firebase.firestore.QuerySnapshot
+import com.google.firebase.firestore.*
 import com.google.firebase.ktx.Firebase
 import com.google.firebase.platforminfo.LibraryVersionComponent
 
@@ -154,6 +149,30 @@ fun firestoreSettings(init: FirebaseFirestoreSettings.Builder.() -> Unit): Fireb
     return builder.build()
 }
 
+inline fun <reified T> GroupSnapshot.getField(field: String): T? = get(field, T::class.java)
+
+inline fun <reified T> GroupSnapshot.getField(
+        field: String,
+        serverTimestampBehavior: DocumentSnapshot.ServerTimestampBehavior
+): T? =
+        get(field, T::class.java, serverTimestampBehavior)
+
+inline fun <reified T> GroupSnapshot.getField(fieldPath: FieldPath): T? = get(fieldPath, T::class.java)
+
+inline fun <reified T> GroupSnapshot.getField(
+        fieldPath: FieldPath,
+        serverTimestampBehavior: DocumentSnapshot.ServerTimestampBehavior
+): T? =
+        get(fieldPath, T::class.java, serverTimestampBehavior)
+
+inline fun <reified T> AggregateSnapshot.getField(field: AggregateField): T? = get(field, T::class.java)
+
+inline fun <reified T> AggregateSnapshot.getField(
+        field: AggregateField,
+        serverTimestampBehavior: DocumentSnapshot.ServerTimestampBehavior
+): T? =
+        get(field, T::class.java, serverTimestampBehavior)
+
 internal const val LIBRARY_NAME: String = "fire-fst-ktx"
 
 /** @suppress */

firebase-firestore/src/main/java/com/google/firebase/firestore/AggregateField.java

@@ -0,0 +1,301 @@
+// Copyright 2022 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.firebase.firestore;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import java.util.Objects;
+
+public abstract class AggregateField {
+
+  private AggregateField() {}
+
+  @NonNull
+  public static CountAggregateField count() {
+    return new CountAggregateField();
+  }
+
+  @NonNull
+  public static MinAggregateField min(@NonNull String field) {
+    return min(FieldPath.fromDotSeparatedPath(field));
+  }
+
+  @NonNull
+  public static MinAggregateField min(@NonNull FieldPath field) {
+    return new MinAggregateField(field);
+  }
+
+  @NonNull
+  public static MaxAggregateField max(@NonNull String field) {
+    return max(FieldPath.fromDotSeparatedPath(field));
+  }
+
+  @NonNull
+  public static MaxAggregateField max(@NonNull FieldPath field) {
+    return new MaxAggregateField(field);
+  }
+
+  @NonNull
+  public static AverageAggregateField average(@NonNull String field) {
+    return average(FieldPath.fromDotSeparatedPath(field));
+  }
+
+  @NonNull
+  public static AverageAggregateField average(@NonNull FieldPath field) {
+    return new AverageAggregateField(field);
+  }
+
+  @NonNull
+  public static SumAggregateField sum(@NonNull String field) {
+    return sum(FieldPath.fromDotSeparatedPath(field));
+  }
+
+  @NonNull
+  public static SumAggregateField sum(@NonNull FieldPath field) {
+    return new SumAggregateField(field);
+  }
+
+  @NonNull
+  public static FirstAggregateField first(@NonNull String field) {
+    return first(FieldPath.fromDotSeparatedPath(field));
+  }
+
+  @NonNull
+  public static FirstAggregateField first(@NonNull FieldPath field) {
+    return new FirstAggregateField(field);
+  }
+
+  @NonNull
+  public static LastAggregateField last(@NonNull String field) {
+    return last(FieldPath.fromDotSeparatedPath(field));
+  }
+
+  @NonNull
+  public static LastAggregateField last(@NonNull FieldPath field) {
+    return new LastAggregateField(field);
+  }
+
+  @Override
+  public abstract boolean equals(Object obj);
+
+  @Override
+  public abstract int hashCode();
+
+  @Override
+  public abstract String toString();
+
+  public static final class CountAggregateField extends AggregateField {
+
+    @Nullable private Integer upTo;
+
+    CountAggregateField() {}
+
+    CountAggregateField(@Nullable Integer upTo) {
+      this.upTo = upTo;
+    }
+
+    public CountAggregateField upTo(int upTo) {
+      if (upTo < 0) {
+        throw new IllegalArgumentException("upTo==" + upTo);
+      }
+      return new CountAggregateField(upTo);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+      if (obj == null || obj.getClass() != this.getClass()) {
+        return false;
+      }
+      CountAggregateField other = (CountAggregateField) obj;
+      return Objects.equals(upTo, other.upTo);
+    }
+
+    @Override
+    public int hashCode() {
+      return Objects.hash("COUNT", upTo);
+    }
+
+    @Override
+    public String toString() {
+      if (upTo == null) {
+        return "COUNT";
+      } else {
+        return "COUNT(upTo=" + upTo + ")";
+      }
+    }
+  }
+
+  public static final class MinAggregateField extends AggregateField {
+
+    @NonNull private FieldPath field;
+
+    MinAggregateField(@NonNull FieldPath field) {
+      this.field = field;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+      if (obj == null || obj.getClass() != this.getClass()) {
+        return false;
+      }
+      return field.equals(((MinAggregateField) obj).field);
+    }
+
+    @Override
+    public int hashCode() {
+      return toString().hashCode();
+    }
+
+    @Override
+    public String toString() {
+      return "MIN(" + field.toString() + ")";
+    }
+  }
+
+  public static final class MaxAggregateField extends AggregateField {
+
+    @NonNull private FieldPath field;
+
+    MaxAggregateField(@NonNull FieldPath field) {
+      this.field = field;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+      if (obj == null || obj.getClass() != this.getClass()) {
+        return false;
+      }
+      return field.equals(((MaxAggregateField) obj).field);
+    }
+
+    @Override
+    public int hashCode() {
+      return toString().hashCode();
+    }
+
+    @Override
+    public String toString() {
+      return "MAX(" + field.toString() + ")";
+    }
+  }
+
+  public static final class AverageAggregateField extends AggregateField {
+
+    @NonNull private FieldPath field;
+
+    AverageAggregateField(@NonNull FieldPath field) {
+      this.field = field;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+      if (obj == null || obj.getClass() != this.getClass()) {
+        return false;
+      }
+      return field.equals(((AverageAggregateField) obj).field);
+    }
+
+    @Override
+    public int hashCode() {
+      return toString().hashCode();
+    }
+
+    @Override
+    public String toString() {
+      return "AVERAGE(" + field.toString() + ")";
+    }
+  }
+
+  public static final class SumAggregateField extends AggregateField {
+
+    @NonNull private FieldPath field;
+
+    SumAggregateField(@NonNull FieldPath field) {
+      this.field = field;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+      if (obj == null || obj.getClass() != this.getClass()) {
+        return false;
+      }
+      return field.equals(((SumAggregateField) obj).field);
+    }
+
+    @Override
+    public int hashCode() {
+      return toString().hashCode();
+    }
+
+    @Override
+    public String toString() {
+      return "SUM(" + field.toString() + ")";
+    }
+  }
+
+  public static final class FirstAggregateField extends AggregateField {
+
+    @NonNull private FieldPath field;
+
+    FirstAggregateField(@NonNull FieldPath field) {
+      this.field = field;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+      if (obj == null || obj.getClass() != this.getClass()) {
+        return false;
+      }
+      return field.equals(((FirstAggregateField) obj).field);
+    }
+
+    @Override
+    public int hashCode() {
+      return toString().hashCode();
+    }
+
+    @Override
+    public String toString() {
+      return "FIRST(" + field.toString() + ")";
+    }
+  }
+
+  public static final class LastAggregateField extends AggregateField {
+
+    @NonNull private FieldPath field;
+
+    LastAggregateField(@NonNull FieldPath field) {
+      this.field = field;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+      if (obj == null || obj.getClass() != this.getClass()) {
+        return false;
+      }
+      return field.equals(((LastAggregateField) obj).field);
+    }
+
+    @Override
+    public int hashCode() {
+      return toString().hashCode();
+    }
+
+    @Override
+    public String toString() {
+      return "LAST(" + field.toString() + ")";
+    }
+  }
+}