feat: Added BQSchemaToProtoSchema functionality along with test cases…

…; checked for linting

google-cloud-bigquerystorage/pom.xml

@@ -108,6 +108,12 @@
       <groupId>org.apache.commons</groupId>
       <artifactId>commons-lang3</artifactId>
     </dependency>
+    <dependency>
+      <groupId>org.json</groupId>
+      <artifactId>json</artifactId>
+      <version>20200518</version>
+  </dependency>
+
 
     <!-- Test dependencies -->
     <dependency>

google-cloud-bigquerystorage/src/main/java/com/google/cloud/bigquery/storage/v1alpha2/JsonToProtoConverter.java

@@ -0,0 +1,150 @@
+/*
+ * Copyright 2020 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.cloud.bigquery.storage.v1alpha2;
+
+import com.google.common.collect.ImmutableMap;
+import com.google.protobuf.DescriptorProtos.DescriptorProto;
+import com.google.protobuf.DescriptorProtos.FieldDescriptorProto;
+import com.google.protobuf.DescriptorProtos.FileDescriptorProto;
+import com.google.protobuf.Descriptors;
+import com.google.protobuf.Descriptors.Descriptor;
+import com.google.protobuf.Descriptors.FileDescriptor;
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * A class that checks the schema compatibility between user schema in proto descriptor and Bigquery
+ * table schema. If this check is passed, then user can write to BigQuery table using the user
+ * schema, otherwise the write will fail.
+ *
+ * <p>The implementation as of now is not complete, which measn, if this check passed, there is
+ * still a possbility of writing will fail.
+ */
+public class JsonToProtoConverter {
+  private static ImmutableMap<Table.TableFieldSchema.Mode, FieldDescriptorProto.Label>
+      BQTableSchemaModeMap =
+          ImmutableMap.of(
+              Table.TableFieldSchema.Mode.NULLABLE, FieldDescriptorProto.Label.LABEL_OPTIONAL,
+              Table.TableFieldSchema.Mode.REPEATED, FieldDescriptorProto.Label.LABEL_REPEATED,
+              Table.TableFieldSchema.Mode.REQUIRED, FieldDescriptorProto.Label.LABEL_REQUIRED);
+
+  private static ImmutableMap<Table.TableFieldSchema.Type, FieldDescriptorProto.Type>
+      BQTableSchemaTypeMap =
+          new ImmutableMap.Builder<Table.TableFieldSchema.Type, FieldDescriptorProto.Type>()
+              .put(Table.TableFieldSchema.Type.BOOL, FieldDescriptorProto.Type.TYPE_BOOL)
+              .put(Table.TableFieldSchema.Type.BYTES, FieldDescriptorProto.Type.TYPE_BYTES)
+              .put(Table.TableFieldSchema.Type.DATE, FieldDescriptorProto.Type.TYPE_INT64)
+              .put(Table.TableFieldSchema.Type.DATETIME, FieldDescriptorProto.Type.TYPE_INT64)
+              .put(Table.TableFieldSchema.Type.DOUBLE, FieldDescriptorProto.Type.TYPE_DOUBLE)
+              .put(Table.TableFieldSchema.Type.GEOGRAPHY, FieldDescriptorProto.Type.TYPE_BYTES)
+              .put(Table.TableFieldSchema.Type.INT64, FieldDescriptorProto.Type.TYPE_INT64)
+              .put(Table.TableFieldSchema.Type.NUMERIC, FieldDescriptorProto.Type.TYPE_DOUBLE)
+              .put(Table.TableFieldSchema.Type.STRING, FieldDescriptorProto.Type.TYPE_STRING)
+              .put(Table.TableFieldSchema.Type.STRUCT, FieldDescriptorProto.Type.TYPE_MESSAGE)
+              .put(Table.TableFieldSchema.Type.TIME, FieldDescriptorProto.Type.TYPE_INT64)
+              .put(Table.TableFieldSchema.Type.TIMESTAMP, FieldDescriptorProto.Type.TYPE_INT64)
+              .build();
+
+  /**
+   * Converts Table.TableSchema to a Descriptors.Descriptor object.
+   *
+   * @param BQTableSchema
+   * @throws Descriptors.DescriptorValidationException
+   */
+  public static Descriptor BQTableSchemaToProtoSchema(Table.TableSchema BQTableSchema)
+      throws Descriptors.DescriptorValidationException {
+    Descriptor descriptor = BQTableSchemaToProtoSchemaImpl(BQTableSchema, "root");
+    return descriptor;
+  }
+
+  /**
+   * Implementation that converts a Table.TableSchema to a Descriptors.Descriptor object.
+   *
+   * @param BQTableSchema
+   * @param scope Keeps track of current scope to prevent repeated naming while constructing
+   *     descriptor.
+   * @throws Descriptors.DescriptorValidationException
+   */
+  private static Descriptor BQTableSchemaToProtoSchemaImpl(
+      Table.TableSchema BQTableSchema, String scope)
+      throws Descriptors.DescriptorValidationException {
+    List<FileDescriptor> dependenciesList = new ArrayList<FileDescriptor>();
+    List<FieldDescriptorProto> fields = new ArrayList<FieldDescriptorProto>();
+    int index = 1;
+    for (Table.TableFieldSchema BQTableField : BQTableSchema.getFieldsList()) {
+      if (BQTableField.getType() == Table.TableFieldSchema.Type.STRUCT) {
+        String currentScope = scope + BQTableField.getName();
+        dependenciesList.add(
+            BQTableSchemaToProtoSchemaImpl(
+                    Table.TableSchema.newBuilder()
+                        .addAllFields(BQTableField.getFieldsList())
+                        .build(),
+                    currentScope)
+                .getFile());
+        fields.add(BQStructToProtoMessage(BQTableField, index++, currentScope));
+      } else {
+        fields.add(BQTableFieldToProtoField(BQTableField, index++));
+      }
+    }
+    FileDescriptor[] dependenciesArray = new FileDescriptor[dependenciesList.size()];
+    dependenciesArray = dependenciesList.toArray(dependenciesArray);
+    DescriptorProto descriptorProto =
+        DescriptorProto.newBuilder().setName(scope).addAllField(fields).build();
+    FileDescriptorProto fileDescriptorProto =
+        FileDescriptorProto.newBuilder().addMessageType(descriptorProto).build();
+    FileDescriptor fileDescriptor =
+        FileDescriptor.buildFrom(fileDescriptorProto, dependenciesArray);
+    Descriptor descriptor = fileDescriptor.findMessageTypeByName(scope);
+    return descriptor;
+  }
+
+  /**
+   * Constructs a FieldDescriptorProto for non-struct BQ fields.
+   *
+   * @param BQTableField BQ Field used to construct a FieldDescriptorProto
+   * @param index Index for protobuf fields.
+   */
+  private static FieldDescriptorProto BQTableFieldToProtoField(
+      Table.TableFieldSchema BQTableField, int index) {
+    String fieldName = BQTableField.getName();
+    Table.TableFieldSchema.Mode mode = BQTableField.getMode();
+    return FieldDescriptorProto.newBuilder()
+        .setName(fieldName)
+        .setType((FieldDescriptorProto.Type) BQTableSchemaTypeMap.get(BQTableField.getType()))
+        .setLabel((FieldDescriptorProto.Label) BQTableSchemaModeMap.get(mode))
+        .setNumber(index)
+        .build();
+  }
+
+  /**
+   * Constructs a FieldDescriptorProto for a Struct type BQ field.
+   *
+   * @param BQTableField BQ Field used to construct a FieldDescriptorProto
+   * @param index Index for protobuf fields.
+   * @param scope Need scope to prevent naming issues
+   */
+  private static FieldDescriptorProto BQStructToProtoMessage(
+      Table.TableFieldSchema BQTableField, int index, String scope) {
+    String fieldName = BQTableField.getName();
+    Table.TableFieldSchema.Mode mode = BQTableField.getMode();
+    return FieldDescriptorProto.newBuilder()
+        .setName(fieldName)
+        .setTypeName(scope)
+        .setLabel((FieldDescriptorProto.Label) BQTableSchemaModeMap.get(mode))
+        .setNumber(index)
+        .build();
+  }
+}

google-cloud-bigquerystorage/src/test/java/com/google/cloud/bigquery/storage/v1alpha2/JsonToProtoConverterTest.java

@@ -0,0 +1,105 @@
+/*
+ * Copyright 2020 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.cloud.bigquery.storage.v1alpha2;
+
+import static org.junit.Assert.*;
+import static org.mockito.Mockito.*;
+
+import com.google.cloud.bigquery.storage.test.SchemaTest.*;
+import com.google.common.collect.ImmutableMap;
+import com.google.protobuf.Descriptors.Descriptor;
+import com.google.protobuf.Descriptors.FieldDescriptor;
+import java.util.Map;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+@RunWith(JUnit4.class)
+public class JsonToProtoConverterTest {
+  private static ImmutableMap<Table.TableFieldSchema.Type, Descriptor>
+      BQTableTypeToProtoDescriptor =
+          new ImmutableMap.Builder<Table.TableFieldSchema.Type, Descriptor>()
+              .put(Table.TableFieldSchema.Type.BOOL, BoolType.getDescriptor())
+              .put(Table.TableFieldSchema.Type.BYTES, BytesType.getDescriptor())
+              .put(Table.TableFieldSchema.Type.DATE, Int64Type.getDescriptor())
+              .put(Table.TableFieldSchema.Type.DATETIME, Int64Type.getDescriptor())
+              .put(Table.TableFieldSchema.Type.DOUBLE, DoubleType.getDescriptor())
+              .put(Table.TableFieldSchema.Type.GEOGRAPHY, BytesType.getDescriptor())
+              .put(Table.TableFieldSchema.Type.INT64, Int64Type.getDescriptor())
+              .put(Table.TableFieldSchema.Type.NUMERIC, DoubleType.getDescriptor())
+              .put(Table.TableFieldSchema.Type.STRING, StringType.getDescriptor())
+              .put(Table.TableFieldSchema.Type.TIME, Int64Type.getDescriptor())
+              .put(Table.TableFieldSchema.Type.TIMESTAMP, Int64Type.getDescriptor())
+              .build();
+
+  private boolean isDescriptorEqual(Descriptor convertedProto, Descriptor originalProto) {
+    for (FieldDescriptor convertedField : convertedProto.getFields()) {
+      FieldDescriptor originalField = originalProto.findFieldByName(convertedField.getName());
+      if (originalField == null) {
+        return false;
+      }
+      FieldDescriptor.Type convertedType = convertedField.getType();
+      FieldDescriptor.Type originalType = originalField.getType();
+      if (convertedType != originalType) {
+        return false;
+      }
+      if (convertedType == FieldDescriptor.Type.MESSAGE) {
+        if (!isDescriptorEqual(convertedField.getMessageType(), originalField.getMessageType())) {
+          return false;
+        }
+      }
+    }
+    return true;
+  }
+
+  @Test
+  public void testBQTableSchemaToProtoDescriptorSimpleTypes() throws Exception {
+    for (Map.Entry<Table.TableFieldSchema.Type, Descriptor> entry :
+        BQTableTypeToProtoDescriptor.entrySet()) {
+      Table.TableFieldSchema tableFieldSchema =
+          Table.TableFieldSchema.newBuilder()
+              .setType(entry.getKey())
+              .setMode(Table.TableFieldSchema.Mode.NULLABLE)
+              .setName("test_field_type")
+              .build();
+      Table.TableSchema tableSchema =
+          Table.TableSchema.newBuilder().addFields(0, tableFieldSchema).build();
+      Descriptor descriptor = JsonToProtoConverter.BQTableSchemaToProtoSchema(tableSchema);
+      assertTrue(isDescriptorEqual(descriptor, entry.getValue()));
+    }
+  }
+
+  @Test
+  public void testBQTableSchemaToProtoDescriptorComplex() throws Exception {
+    Table.TableFieldSchema StringType =
+        Table.TableFieldSchema.newBuilder()
+            .setType(Table.TableFieldSchema.Type.STRING)
+            .setMode(Table.TableFieldSchema.Mode.NULLABLE)
+            .setName("test_field_type")
+            .build();
+    Table.TableFieldSchema tableFieldSchema =
+        Table.TableFieldSchema.newBuilder()
+            .setType(Table.TableFieldSchema.Type.STRUCT)
+            .setMode(Table.TableFieldSchema.Mode.NULLABLE)
+            .setName("test_field_type")
+            .addFields(0, StringType)
+            .build();
+    Table.TableSchema tableSchema =
+        Table.TableSchema.newBuilder().addFields(0, tableFieldSchema).build();
+    Descriptor descriptor = JsonToProtoConverter.BQTableSchemaToProtoSchema(tableSchema);
+    assertTrue(isDescriptorEqual(descriptor, MessageType.getDescriptor()));
+  }
+}