[GitHub] [hudi] xushiyan commented on a diff in pull request #7727: [HUDI-2608] Support json schema in SchemaRegistryProvider

["xushiyan (via GitHub)" <gi...@apache.org>]

xushiyan commented on code in PR #7727:
URL: https://github.com/apache/hudi/pull/7727#discussion_r1085414248


##########
hudi-utilities/src/main/java/org/apache/hudi/utilities/schema/converter/JsonToAvroSchemaConverter.java:
##########
@@ -0,0 +1,250 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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 org.apache.hudi.utilities.schema.converter;
+
+import org.apache.hudi.common.util.JsonUtils;
+import org.apache.hudi.common.util.Option;
+import org.apache.hudi.utilities.schema.SchemaRegistryProvider;
+
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.node.ArrayNode;
+import com.fasterxml.jackson.databind.node.NullNode;
+import com.fasterxml.jackson.databind.node.ObjectNode;
+import com.fasterxml.jackson.databind.node.TextNode;
+
+import java.io.IOException;
+import java.net.URI;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Set;
+import java.util.regex.Pattern;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+import static org.apache.hudi.common.util.StringUtils.getSuffixBy;
+import static org.apache.hudi.common.util.StringUtils.removeSuffixBy;
+
+public class JsonToAvroSchemaConverter implements SchemaRegistryProvider.SchemaConverter {
+
+  private static final ObjectMapper MAPPER = JsonUtils.getObjectMapper();
+  private static final Map<String, String> JSON_TO_AVRO_TYPE = Stream.of(new String[][] {
+      {"string", "string"},
+      {"null", "null"},
+      {"boolean", "boolean"},
+      {"integer", "long"},
+      {"number", "double"}
+  }).collect(Collectors.collectingAndThen(Collectors.toMap(p -> p[0], p -> p[1]), Collections::<String, String>unmodifiableMap));
+  private static final Pattern SYMBOL_REGEX = Pattern.compile("^[A-Za-z_][A-Za-z0-9_]*$");
+
+  @Override
+  public String convert(String jsonSchema) throws IOException {
+    JsonNode jsonNode = MAPPER.readTree(jsonSchema);
+    ObjectNode avroRecord = MAPPER.createObjectNode()
+        .put("type", "record")
+        .put("name", getAvroSchemaRecordName(jsonNode))
+        .put("doc", getAvroDoc(jsonNode));
+    Option<String> namespace = getAvroSchemaRecordNamespace(jsonNode);
+    if (namespace.isPresent()) {
+      avroRecord.put("namespace", namespace.get());
+    }
+    if (jsonNode.hasNonNull("properties")) {
+      avroRecord.set("fields", convertProperties(jsonNode.get("properties"), getRequired(jsonNode)));
+    } else {
+      avroRecord.set("fields", MAPPER.createArrayNode());
+    }
+    return avroRecord.toString();
+  }
+
+  private static ArrayNode convertProperties(JsonNode jsonProperties, Set<String> required) {
+    List<JsonNode> avroFields = new ArrayList<>();
+    jsonProperties.fieldNames().forEachRemaining(name ->
+        avroFields.add(tryConvertNestedProperty(name, jsonProperties.get(name))
+            .or(tryConvertArrayProperty(name, jsonProperties.get(name)))
+            .or(tryConvertEnumProperty(name, jsonProperties.get(name)))
+            .orElse(convertProperty(name, jsonProperties.get(name), required.contains(name)))));
+    return MAPPER.createArrayNode().addAll(avroFields);
+  }
+
+  private static Option<JsonNode> tryConvertNestedProperty(String name, JsonNode jsonProperty) {
+    if (!isJsonNestedType(jsonProperty)) {
+      return Option.empty();
+    }
+    JsonNode avroNode = MAPPER.createObjectNode()
+        .put("name", sanitizeAsAvroName(name))
+        .put("doc", getAvroDoc(jsonProperty))
+        .set("type", MAPPER.createObjectNode()
+            .put("type", "record")
+            .put("name", getAvroTypeName(jsonProperty, name))
+            .set("fields", convertProperties(jsonProperty.get("properties"), getRequired(jsonProperty))));
+
+    return Option.of(avroNode);
+  }
+
+  private static Option<JsonNode> tryConvertArrayProperty(String name, JsonNode jsonProperty) {
+    if (!isJsonArrayType(jsonProperty)) {
+      return Option.empty();
+    }
+    JsonNode avroItems;
+    JsonNode jsonItems = jsonProperty.get("items");
+    String itemName = getAvroTypeName(jsonItems, name) + "_child";
+    if (isJsonNestedType(jsonItems)) {
+      avroItems = MAPPER.createObjectNode()
+          .put("type", "record")
+          .put("name", itemName)
+          .set("fields", convertProperties(jsonItems.get("properties"), getRequired(jsonItems)));
+    } else {
+      avroItems = convertProperty(itemName, jsonItems, true);
+    }
+    JsonNode avroNode = MAPPER.createObjectNode()
+        .put("name", sanitizeAsAvroName(name))
+        .put("doc", getAvroDoc(jsonProperty))
+        .set("type", MAPPER.createObjectNode()
+            .put("type", "array")
+            .set("items", avroItems));
+
+    return Option.of(avroNode);
+  }
+
+  private static Option<JsonNode> tryConvertEnumProperty(String name, JsonNode jsonProperty) {
+    if (!isJsonEnumType(jsonProperty)) {
+      return Option.empty();
+    }
+    List<String> enums = new ArrayList<>();
+    jsonProperty.get("enum").iterator().forEachRemaining(e -> enums.add(e.asText()));
+    JsonNode avroType = enums.stream().allMatch(e -> SYMBOL_REGEX.matcher(e).matches())
+        ? MAPPER.createObjectNode()
+        .put("type", "enum")
+        .put("name", getAvroTypeName(jsonProperty, name))
+        .set("symbols", jsonProperty.get("enum"))
+        : TextNode.valueOf("string");
+    JsonNode avroNode = MAPPER.createObjectNode()
+        .put("name", sanitizeAsAvroName(name))
+        .put("doc", getAvroDoc(jsonProperty))
+        .set("type", avroType);
+
+    return Option.of(avroNode);
+  }
+
+  private static JsonNode convertProperty(String name, JsonNode jsonProperty, boolean isRequired) {
+    ObjectNode avroNode = MAPPER.createObjectNode()
+        .put("name", sanitizeAsAvroName(name))
+        .put("doc", getAvroDoc(jsonProperty));
+
+    // infer `default`
+    boolean nullable = !isRequired;
+    if (jsonProperty.has("default")) {
+      avroNode.set("default", jsonProperty.get("default"));
+    } else if (nullable) {
+      avroNode.set("default", NullNode.getInstance());
+    }
+
+    // infer `types`
+    Set<String> avroTypeSet = new HashSet<>();
+    if (jsonProperty.hasNonNull("oneOf") || jsonProperty.hasNonNull("allOf")) {
+      // prefer to look for `oneOf` and `allOf` for types
+      Option<JsonNode> oneOfTypes = Option.ofNullable(jsonProperty.get("oneOf"));
+      if (oneOfTypes.isPresent()) {
+        oneOfTypes.get().elements().forEachRemaining(e -> avroTypeSet.add(JSON_TO_AVRO_TYPE.get(e.get("type").asText())));
+      }
+      Option<JsonNode> allOfTypes = Option.ofNullable(jsonProperty.get("allOf"));
+      if (allOfTypes.isPresent()) {
+        allOfTypes.get().elements().forEachRemaining(e -> avroTypeSet.add(JSON_TO_AVRO_TYPE.get(e.get("type").asText())));
+      }
+    } else if (jsonProperty.has("type")) {
+      // fall back to `type` parameter
+      JsonNode jsonType = jsonProperty.get("type");
+      if (jsonType.isArray()) {
+        jsonType.elements().forEachRemaining(e -> avroTypeSet.add(JSON_TO_AVRO_TYPE.get(e.asText())));
+      } else {
+        avroTypeSet.add(JSON_TO_AVRO_TYPE.get(jsonType.asText()));
+      }
+    }
+    List<String> avroTypes = new ArrayList<>();
+    if (nullable || avroTypeSet.contains("null")) {
+      avroTypes.add("null");
+    }
+    avroTypeSet.remove("null");
+    avroTypes.addAll(avroTypeSet);
+    avroNode.set("type", avroTypes.size() > 1
+        ? MAPPER.createArrayNode().addAll(avroTypes.stream().map(TextNode::valueOf).collect(Collectors.toList()))
+        : TextNode.valueOf(avroTypes.get(0)));
+    return avroNode;
+  }
+
+  private static boolean isJsonNestedType(JsonNode jsonNode) {
+    return jsonNode.has("type") && Objects.equals(jsonNode.get("type").asText(), "object");
+  }
+
+  private static boolean isJsonArrayType(JsonNode jsonNode) {
+    return jsonNode.has("type") && Objects.equals(jsonNode.get("type").asText(), "array");
+  }
+
+  private static boolean isJsonEnumType(JsonNode jsonNode) {
+    return jsonNode.hasNonNull("enum") && jsonNode.get("enum").isArray();
+  }
+
+  private static Option<String> getAvroSchemaRecordNamespace(JsonNode jsonNode) {
+    if (jsonNode.hasNonNull("$id")) {
+      return Option.of(URI.create(jsonNode.get("$id").asText()).getHost());
+    }
+    return Option.empty();
+  }
+
+  private static String getAvroSchemaRecordName(JsonNode jsonNode) {
+    if (jsonNode.hasNonNull("title")) {
+      return sanitizeAsAvroName(jsonNode.get("title").asText());
+    }
+    if (jsonNode.hasNonNull("$id")) {
+      // infer name from host: http://www.my-example.com => "my_example"
+      String host = URI.create(jsonNode.get("$id").asText()).getHost();

Review Comment:
   the comment here is meant for the if block not just the URI.create



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