feat: Adding JsonToProtoMessage.java

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/JsonToProtoMessage.java

@@ -0,0 +1,323 @@
+/*
+ * 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.base.Preconditions;
+import com.google.common.collect.ImmutableMap;
+import com.google.protobuf.Descriptors.Descriptor;
+import com.google.protobuf.Descriptors.FieldDescriptor;
+import com.google.protobuf.DynamicMessage;
+import com.google.protobuf.Message;
+import com.google.protobuf.UninitializedMessageException;
+import org.json.JSONArray;
+import org.json.JSONException;
+import org.json.JSONObject;
+
+/**
+ * Converts Json data to protocol buffer messages given the protocol buffer descriptor. The protobuf
+ * descriptor must have all fields lowercased.
+ */
+public class JsonToProtoMessage {
+  private static ImmutableMap<FieldDescriptor.Type, String> FieldTypeToDebugMessage =
+      new ImmutableMap.Builder<FieldDescriptor.Type, String>()
+          .put(FieldDescriptor.Type.BOOL, "boolean")
+          .put(FieldDescriptor.Type.BYTES, "string")
+          .put(FieldDescriptor.Type.INT32, "int32")
+          .put(FieldDescriptor.Type.DOUBLE, "double")
+          .put(FieldDescriptor.Type.INT64, "int64")
+          .put(FieldDescriptor.Type.STRING, "string")
+          .put(FieldDescriptor.Type.MESSAGE, "object")
+          .build();
+
+  /**
+   * Converts Json data to protocol buffer messages given the protocol buffer descriptor.
+   *
+   * @param protoSchema
+   * @param json
+   * @param allowUnknownFields Ignores unknown JSON fields.
+   * @throws IllegalArgumentException when JSON data is not compatible with proto descriptor.
+   */
+  public static DynamicMessage convertJsonToProtoMessage(
+      Descriptor protoSchema, JSONObject json, boolean allowUnknownFields)
+      throws IllegalArgumentException {
+    Preconditions.checkNotNull(json, "JSONObject is null.");
+    Preconditions.checkNotNull(protoSchema, "Protobuf descriptor is null.");
+    Preconditions.checkState(json.length() != 0, "JSONObject is empty.");
+
+    return convertJsonToProtoMessageImpl(
+        protoSchema, json, "root", /*topLevel=*/ true, allowUnknownFields);
+  }
+
+  /**
+   * Converts Json data to protocol buffer messages given the protocol buffer descriptor.
+   *
+   * @param protoSchema
+   * @param json
+   * @param jsonScope Debugging purposes
+   * @param allowUnknownFields Ignores unknown JSON fields.
+   * @param topLevel checks if root level has any matching fields.
+   * @throws IllegalArgumentException when JSON data is not compatible with proto descriptor.
+   */
+  private static DynamicMessage convertJsonToProtoMessageImpl(
+      Descriptor protoSchema,
+      JSONObject json,
+      String jsonScope,
+      boolean topLevel,
+      boolean allowUnknownFields)
+      throws IllegalArgumentException {
+
+    DynamicMessage.Builder protoMsg = DynamicMessage.newBuilder(protoSchema);
+    String[] jsonNames = JSONObject.getNames(json);
+    if (jsonNames == null) {
+      return protoMsg.build();
+    }
+    int matchedFields = 0;
+    for (int i = 0; i < jsonNames.length; i++) {
+      String jsonName = jsonNames[i];
+      // We want lowercase here to support case-insensitive data writes.
+      // The protobuf descriptor that is used is assumed to have all lowercased fields
+      String jsonLowercaseName = jsonName.toLowerCase();
+      String currentScope = jsonScope + "." + jsonName;
+      FieldDescriptor field = protoSchema.findFieldByName(jsonLowercaseName);
+      if (field == null) {
+        if (!allowUnknownFields) {
+          throw new IllegalArgumentException(
+              String.format(
+                  "JSONObject has fields unknown to BigQuery: %s. Set allowUnknownFields to True to allow unknown fields.",
+                  currentScope));
+        } else {
+          continue;
+        }
+      }
+      matchedFields++;
+      if (!field.isRepeated()) {
+        fillField(protoMsg, field, json, jsonName, currentScope, allowUnknownFields);
+      } else {
+        fillRepeatedField(protoMsg, field, json, jsonName, currentScope, allowUnknownFields);
+      }
+    }
+
+    if (matchedFields == 0 && topLevel) {
+      throw new IllegalArgumentException(
+          "There are no matching fields found for the JSONObject and the protocol buffer descriptor.");
+    }
+    DynamicMessage msg;
+    try {
+      msg = protoMsg.build();
+    } catch (UninitializedMessageException e) {
+      String errorMsg = e.getMessage();
+      int idxOfColon = errorMsg.indexOf(":");
+      String missingFieldName = errorMsg.substring(idxOfColon + 2);
+      throw new IllegalArgumentException(
+          String.format(
+              "JSONObject does not have the required field %s.%s.", jsonScope, missingFieldName));
+    }
+    if (topLevel && msg.getSerializedSize() == 0) {
+      throw new IllegalArgumentException("The created protobuf message is empty.");
+    }
+    return msg;
+  }
+
+  /**
+   * Fills a non-repetaed protoField with the json data.
+   *
+   * @param protoMsg The protocol buffer message being constructed
+   * @param fieldDescriptor
+   * @param json
+   * @param exactJsonKeyName Exact key name in JSONObject instead of lowercased version
+   * @param currentScope Debugging purposes
+   * @param allowUnknownFields Ignores unknown JSON fields.
+   * @throws IllegalArgumentException when JSON data is not compatible with proto descriptor.
+   */
+  private static void fillField(
+      DynamicMessage.Builder protoMsg,
+      FieldDescriptor fieldDescriptor,
+      JSONObject json,
+      String exactJsonKeyName,
+      String currentScope,
+      boolean allowUnknownFields)
+      throws IllegalArgumentException {
+
+    java.lang.Object val = json.get(exactJsonKeyName);
+    switch (fieldDescriptor.getType()) {
+      case BOOL:
+        if (val instanceof Boolean) {
+          protoMsg.setField(fieldDescriptor, (Boolean) val);
+          return;
+        }
+        break;
+      case BYTES:
+        if (val instanceof String) {
+          protoMsg.setField(fieldDescriptor, ((String) val).getBytes());
+          return;
+        }
+        break;
+      case INT64:
+        if (val instanceof Integer) {
+          protoMsg.setField(fieldDescriptor, new Long((Integer) val));
+          return;
+        } else if (val instanceof Long) {
+          protoMsg.setField(fieldDescriptor, (Long) val);
+          return;
+        }
+        break;
+      case INT32:
+        if (val instanceof Integer) {
+          protoMsg.setField(fieldDescriptor, (Integer) val);
+          return;
+        }
+        break;
+      case STRING:
+        if (val instanceof String) {
+          protoMsg.setField(fieldDescriptor, (String) val);
+          return;
+        }
+        break;
+      case DOUBLE:
+        if (val instanceof Double) {
+          protoMsg.setField(fieldDescriptor, (Double) val);
+          return;
+        } else if (val instanceof Float) {
+          protoMsg.setField(fieldDescriptor, new Double((Float) val));
+          return;
+        }
+        break;
+      case MESSAGE:
+        if (val instanceof JSONObject) {
+          Message.Builder message = protoMsg.newBuilderForField(fieldDescriptor);
+          protoMsg.setField(
+              fieldDescriptor,
+              convertJsonToProtoMessageImpl(
+                  fieldDescriptor.getMessageType(),
+                  json.getJSONObject(exactJsonKeyName),
+                  currentScope,
+                  /*topLevel =*/ false,
+                  allowUnknownFields));
+          return;
+        }
+        break;
+    }
+    throw new IllegalArgumentException(
+        String.format(
+            "JSONObject does not have a %s field at %s.",
+            FieldTypeToDebugMessage.get(fieldDescriptor.getType()), currentScope));
+  }
+
+  /**
+   * Fills a repeated protoField with the json data.
+   *
+   * @param protoMsg The protocol buffer message being constructed
+   * @param fieldDescriptor
+   * @param json If root level has no matching fields, throws exception.
+   * @param exactJsonKeyName Exact key name in JSONObject instead of lowercased version
+   * @param currentScope Debugging purposes
+   * @param allowUnknownFields Ignores unknown JSON fields.
+   * @throws IllegalArgumentException when JSON data is not compatible with proto descriptor.
+   */
+  private static void fillRepeatedField(
+      DynamicMessage.Builder protoMsg,
+      FieldDescriptor fieldDescriptor,
+      JSONObject json,
+      String exactJsonKeyName,
+      String currentScope,
+      boolean allowUnknownFields)
+      throws IllegalArgumentException {
+
+    JSONArray jsonArray;
+    try {
+      jsonArray = json.getJSONArray(exactJsonKeyName);
+    } catch (JSONException e) {
+      throw new IllegalArgumentException(
+          "JSONObject does not have a array field at " + currentScope + ".");
+    }
+    java.lang.Object val;
+    int index;
+    boolean fail = false;
+    for (int i = 0; i < jsonArray.length(); i++) {
+      val = jsonArray.get(i);
+      index = i;
+      switch (fieldDescriptor.getType()) {
+        case BOOL:
+          if (val instanceof Boolean) {
+            protoMsg.addRepeatedField(fieldDescriptor, (Boolean) val);
+          } else {
+            fail = true;
+          }
+          break;
+        case BYTES:
+          if (val instanceof String) {
+            protoMsg.addRepeatedField(fieldDescriptor, ((String) val).getBytes());
+          } else {
+            fail = true;
+          }
+          break;
+        case INT64:
+          if (val instanceof Integer) {
+            protoMsg.addRepeatedField(fieldDescriptor, new Long((Integer) val));
+          } else if (val instanceof Long) {
+            protoMsg.addRepeatedField(fieldDescriptor, (Long) val);
+          } else {
+            fail = true;
+          }
+          break;
+        case INT32:
+          if (val instanceof Integer) {
+            protoMsg.addRepeatedField(fieldDescriptor, (Integer) val);
+          } else {
+            fail = true;
+          }
+          break;
+        case STRING:
+          if (val instanceof String) {
+            protoMsg.addRepeatedField(fieldDescriptor, (String) val);
+          } else {
+            fail = true;
+          }
+          break;
+        case DOUBLE:
+          if (val instanceof Double) {
+            protoMsg.addRepeatedField(fieldDescriptor, (Double) val);
+          } else if (val instanceof Float) {
+            protoMsg.addRepeatedField(fieldDescriptor, new Double((float) val));
+          } else {
+            fail = true;
+          }
+          break;
+        case MESSAGE:
+          if (val instanceof JSONObject) {
+            Message.Builder message = protoMsg.newBuilderForField(fieldDescriptor);
+            protoMsg.addRepeatedField(
+                fieldDescriptor,
+                convertJsonToProtoMessageImpl(
+                    fieldDescriptor.getMessageType(),
+                    jsonArray.getJSONObject(i),
+                    currentScope,
+                    /*topLevel =*/ false,
+                    allowUnknownFields));
+          } else {
+            fail = true;
+          }
+          break;
+      }
+      if (fail) {
+        throw new IllegalArgumentException(
+            String.format(
+                "JSONObject does not have a %s field at %s[%d].",
+                FieldTypeToDebugMessage.get(fieldDescriptor.getType()), currentScope, index));
+      }
+    }
+  }
+}