feature(aws-datastore): support for hybrid platforms (#954)

Resolves: #842
Co-authored-by: Praveen Gupta <[email protected]>

Author: jamesonwilliams

aws-api-appsync/src/main/java/com/amplifyframework/api/aws/AppSyncGraphQLRequest.java

@@ -222,6 +222,16 @@ <R> Builder(AppSyncGraphQLRequest<R> request) {
             this.variableTypes = new HashMap<>(request.variableTypes);
         }
 
+        /**
+         * Sets the {@link ModelSchema} Class and returns this builder.
+         * @param modelSchema the {@link ModelSchema} Class.
+         * @return this builder instance.
+         */
+        public Builder modelSchema(@NonNull ModelSchema modelSchema) {
+            this.modelSchema = Objects.requireNonNull(modelSchema);
+            return Builder.this;
+        }
+
         /**
          * Sets the {@link Model} Class and returns this builder.
          * @param modelClass the {@link Model} Class.
@@ -279,7 +289,6 @@ public Builder variable(@NonNull String key, String type, Object value) {
 
         /**
          * Builds an {@link AppSyncGraphQLRequest}.
-         *
          * @param <R> The type of data contained in the GraphQLResponse expected from this request.
          * @return the AppSyncGraphQLRequest
          * @throws AmplifyException if a ModelSchema cannot be created from the provided model class.
@@ -288,19 +297,29 @@ public <R> AppSyncGraphQLRequest<R> build() throws AmplifyException {
             Objects.requireNonNull(this.operation);
             Objects.requireNonNull(this.responseType);
 
-            if (modelClass != null) {
-                // Derive modelSchema and selectionSet from modelClass.
+            // TODO: if the modelClass is contained within the modelSchema,
+            // why can't we just extract it from the ModelSchema, instead of
+            // having it as an outside parameter?
+            if (modelSchema == null) {
+                if (modelClass == null) {
+                    throw new AmplifyException(
+                        "Both modelSchema and modelClass cannot be null",
+                        AmplifyException.TODO_RECOVERY_SUGGESTION
+                    );
+                }
+                // Derive modelSchema from modelClass if not available
                 modelSchema = ModelSchema.fromModelClass(this.modelClass);
+            }
+
+            // if this Builder was created via newBuilder(),
+            // selectionSet will already be set, so we can continue on.
+            if (selectionSet == null) {
                 selectionSet = SelectionSet.builder()
+                        .modelSchema(this.modelSchema)
                         .modelClass(this.modelClass)
                         .operation(this.operation)
                         .requestOptions(Objects.requireNonNull(this.requestOptions))
                         .build();
-            } else {
-                // If modelClass is null, we can't derive modelSchema and selectionSet.  However, if this Builder was
-                // created via newBuilder(), those fields will already be set, so we can continue on.
-                Objects.requireNonNull(modelSchema, "modelClass must not be null");
-                Objects.requireNonNull(selectionSet, "modelClass must not be null");
             }
             return new AppSyncGraphQLRequest<>(this);
         }

aws-api-appsync/src/main/java/com/amplifyframework/api/aws/SelectionSet.java

@@ -25,8 +25,12 @@
 import com.amplifyframework.core.model.AuthRule;
 import com.amplifyframework.core.model.AuthStrategy;
 import com.amplifyframework.core.model.Model;
+import com.amplifyframework.core.model.ModelAssociation;
+import com.amplifyframework.core.model.ModelField;
 import com.amplifyframework.core.model.ModelSchema;
+import com.amplifyframework.core.model.ModelSchemaRegistry;
 import com.amplifyframework.core.model.types.JavaFieldType;
+import com.amplifyframework.datastore.appsync.SerializedModel;
 import com.amplifyframework.util.Empty;
 import com.amplifyframework.util.FieldFinder;
 import com.amplifyframework.util.Wrap;
@@ -38,6 +42,7 @@
 import java.util.Collections;
 import java.util.HashSet;
 import java.util.List;
+import java.util.Map;
 import java.util.Objects;
 import java.util.Set;
 
@@ -167,6 +172,7 @@ static final class Builder {
         private Class<? extends Model> modelClass;
         private Operation operation;
         private GraphQLRequestOptions requestOptions;
+        private ModelSchema modelSchema;
 
         Builder() { }
 
@@ -175,6 +181,11 @@ public Builder modelClass(@NonNull Class<? extends Model> modelClass) {
             return Builder.this;
         }
 
+        public Builder modelSchema(@NonNull ModelSchema modelSchema) {
+            this.modelSchema = Objects.requireNonNull(modelSchema);
+            return Builder.this;
+        }
+
         public Builder operation(@NonNull Operation operation) {
             this.operation = Objects.requireNonNull(operation);
             return Builder.this;
@@ -191,9 +202,15 @@ public Builder requestOptions(@NonNull GraphQLRequestOptions requestOptions) {
          * @throws AmplifyException if a ModelSchema cannot be created from the provided model class.
          */
         public SelectionSet build() throws AmplifyException {
-            Objects.requireNonNull(this.modelClass);
+            if (this.modelClass == null && this.modelSchema == null) {
+                throw new AmplifyException("Both modelClass and modelSchema cannot be null",
+                        "Provide either a modelClass or a modelSchema to build the selection set");
+            }
             Objects.requireNonNull(this.operation);
-            SelectionSet node = new SelectionSet(null, getModelFields(modelClass, requestOptions.maxDepth()));
+            SelectionSet node = new SelectionSet(null,
+                    SerializedModel.class == modelClass
+                            ? getModelFields(modelSchema, requestOptions.maxDepth())
+                            : getModelFields(modelClass, requestOptions.maxDepth()));
             if (QueryType.LIST.equals(operation) || QueryType.SYNC.equals(operation)) {
                 node = wrapPagination(node);
             }
@@ -222,6 +239,16 @@ private Set<SelectionSet> wrapPagination(Set<SelectionSet> nodes) {
             return paginatedSet;
         }
 
+        /**
+         * Gets a selection set for the given class.
+         * TODO: this is mostly duplicative of {@link #getModelFields(ModelSchema, int)}.
+         * Long-term, we want to remove this current method and rely only on the ModelSchema-based
+         * version.
+         * @param clazz Class from which to build selection set
+         * @param depth Number of children deep to explore
+         * @return Selection Set
+         * @throws AmplifyException On faiulre to build selection set
+         */
         @SuppressWarnings("unchecked") // Cast to Class<Model>
         private Set<SelectionSet> getModelFields(Class<? extends Model> clazz, int depth)
                 throws AmplifyException {
@@ -320,5 +347,40 @@ static Class<?> getClassForField(Field field) {
             }
             return typeClass;
         }
+
+        private Set<SelectionSet> getModelFields(ModelSchema modelSchema, int depth) {
+            if (depth < 0) {
+                return new HashSet<>();
+            }
+            Set<SelectionSet> result = new HashSet<>();
+            if (depth == 0 && LeafSerializationBehavior.JUST_ID.equals(requestOptions.leafSerializationBehavior())) {
+                result.add(new SelectionSet("id"));
+                return result;
+            }
+            for (Map.Entry<String, ModelField> entry : modelSchema.getFields().entrySet()) {
+                String fieldName = entry.getKey();
+                ModelAssociation association = modelSchema.getAssociations().get(fieldName);
+                if (association != null) {
+                    if (depth >= 1) {
+                        String associatedModelName = association.getAssociatedType();
+                        ModelSchema associateModelSchema = ModelSchemaRegistry.instance()
+                                .getModelSchemaForModelClass(associatedModelName);
+                        Set<SelectionSet> fields;
+                        if (entry.getValue().isArray()) { // If modelField is an Array
+                            fields = wrapPagination(getModelFields(associateModelSchema, depth - 1));
+                        } else {
+                            fields = getModelFields(associateModelSchema, depth - 1);
+                        }
+                        result.add(new SelectionSet(fieldName, fields));
+                    }
+                } else {
+                    result.add(new SelectionSet(fieldName));
+                }
+            }
+            for (String fieldName : requestOptions.modelMetaFields()) {
+                result.add(new SelectionSet(fieldName));
+            }
+            return result;
+        }
     }
 }

aws-api-appsync/src/main/java/com/amplifyframework/core/model/types/JavaFieldType.java

@@ -16,6 +16,7 @@
 package com.amplifyframework.core.model.types;
 
 import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
 
 import com.amplifyframework.core.model.Model;
 import com.amplifyframework.core.model.temporal.Temporal;
@@ -97,9 +98,9 @@ public enum JavaFieldType {
      * @param javaFieldType the string representation of the field type.
      * @return the enumeration constant.
      */
-    public static JavaFieldType from(@NonNull Class<?> javaFieldType) {
+    public static JavaFieldType from(@Nullable Class<?> javaFieldType) {
         for (final JavaFieldType type : JavaFieldType.values()) {
-            if (javaFieldType.equals(type.javaFieldType)) {
+            if (type.javaFieldType.equals(javaFieldType)) {
                 return type;
             }
         }