Examples with SchemaParserFactory com.linkedin.data.schema.SchemaParserFactory used on opensource projects

Example 1 with SchemaParserFactory

use of com.linkedin.data.schema.SchemaParserFactory in project rest.li by linkedin.

the class SchemaTranslator method avroToDataSchema.

/**
   * Translate an Avro {@link Schema} to a {@link DataSchema}.
   * <p>
   * If the translation mode is {@link AvroToDataSchemaTranslationMode#RETURN_EMBEDDED_SCHEMA}
   * and a {@link DataSchema} is embedded in the Avro schema, then return the embedded schema.
   * An embedded schema is present if the Avro {@link Schema} has a "com.linkedin.data" property and the
   * "com.linkedin.data" property contains both "schema" and "optionalDefaultMode" properties.
   * The "schema" property provides the embedded {@link DataSchema}.
   * The "optionalDefaultMode" property provides how optional default values were translated.
   * <p>
   * If the translation mode is {@link AvroToDataSchemaTranslationMode#VERIFY_EMBEDDED_SCHEMA}
   * and a {@link DataSchema} is embedded in the Avro schema, then verify that the embedded schema
   * translates to the input Avro schema. If the translated and embedded schema is the same,
   * then return the embedded schema, else throw {@link IllegalArgumentException}.
   * <p>
   * If the translation mode is {@link com.linkedin.data.avro.AvroToDataSchemaTranslationMode#TRANSLATE}
   * or no embedded {@link DataSchema} is present, then this method
   * translates the provided Avro {@link Schema} to a {@link DataSchema}
   * as described follows:
   * <p>
   * This method translates union with null record fields in Avro {@link Schema}
   * to optional fields in {@link DataSchema}. Record fields
   * whose type is a union with null will be translated to a new type, and the field becomes optional.
   * If the Avro union has two types (one of them is the null type), then the new type of the
   * field is the non-null member type of the union. If the Avro union does not have two types
   * (one of them is the null type) then the new type of the field is a union type with the null type
   * removed from the original union.
   * <p>
   * This method also translates default values. If the field's type is a union with null
   * and has a default value, then this method also translates the default value of the field
   * to comply with the new type of the field. If the default value is null,
   * then remove the default value. If new type is not a union and the default value
   * is of the non-null member type, then assign the default value to the
   * non-null value within the union value (i.e. the value of the only entry within the
   * JSON object.) If the new type is a union and the default value is of the
   * non-null member type, then assign the default value to a JSON object
   * containing a single entry with the key being the member type discriminator of
   * the first union member and the value being the actual member value.
   * <p>
   * Both the schema and default value translation takes into account that default value
   * representation for Avro unions does not include the member type discriminator and
   * the type of the default value is always the 1st member of the union.
   *
   * @param avroSchemaInJson provides the JSON representation of the Avro {@link Schema}.
   * @param options specifies the {@link AvroToDataSchemaTranslationOptions}.
   * @return the translated {@link DataSchema}.
   * @throws IllegalArgumentException if the Avro {@link Schema} cannot be translated.
   */
public static DataSchema avroToDataSchema(String avroSchemaInJson, AvroToDataSchemaTranslationOptions options) throws IllegalArgumentException {
    ValidationOptions validationOptions = SchemaParser.getDefaultSchemaParserValidationOptions();
    validationOptions.setAvroUnionMode(true);
    SchemaParserFactory parserFactory = SchemaParserFactory.instance(validationOptions);
    DataSchemaResolver resolver = getResolver(parserFactory, options);
    PegasusSchemaParser parser = parserFactory.create(resolver);
    parser.parse(avroSchemaInJson);
    if (parser.hasError()) {
        throw new IllegalArgumentException(parser.errorMessage());
    }
    assert (parser.topLevelDataSchemas().size() == 1);
    DataSchema dataSchema = parser.topLevelDataSchemas().get(0);
    DataSchema resultDataSchema = null;
    AvroToDataSchemaTranslationMode translationMode = options.getTranslationMode();
    if (translationMode == AvroToDataSchemaTranslationMode.RETURN_EMBEDDED_SCHEMA || translationMode == AvroToDataSchemaTranslationMode.VERIFY_EMBEDDED_SCHEMA) {
        // check for embedded schema
        Object dataProperty = dataSchema.getProperties().get(SchemaTranslator.DATA_PROPERTY);
        if (dataProperty != null && dataProperty.getClass() == DataMap.class) {
            Object schemaProperty = ((DataMap) dataProperty).get(SchemaTranslator.SCHEMA_PROPERTY);
            if (schemaProperty.getClass() == DataMap.class) {
                SchemaParser embeddedSchemaParser = SchemaParserFactory.instance().create(null);
                embeddedSchemaParser.parse(Arrays.asList(schemaProperty));
                if (embeddedSchemaParser.hasError()) {
                    throw new IllegalArgumentException("Embedded schema is invalid\n" + embeddedSchemaParser.errorMessage());
                }
                assert (embeddedSchemaParser.topLevelDataSchemas().size() == 1);
                resultDataSchema = embeddedSchemaParser.topLevelDataSchemas().get(0);
                if (translationMode == AvroToDataSchemaTranslationMode.VERIFY_EMBEDDED_SCHEMA) {
                    // additional verification to make sure that embedded schema translates to Avro schema
                    DataToAvroSchemaTranslationOptions dataToAvdoSchemaOptions = new DataToAvroSchemaTranslationOptions();
                    Object optionalDefaultModeProperty = ((DataMap) dataProperty).get(SchemaTranslator.OPTIONAL_DEFAULT_MODE_PROPERTY);
                    dataToAvdoSchemaOptions.setOptionalDefaultMode(OptionalDefaultMode.valueOf(optionalDefaultModeProperty.toString()));
                    Schema avroSchemaFromEmbedded = dataToAvroSchema(resultDataSchema, dataToAvdoSchemaOptions);
                    Schema avroSchemaFromJson = Schema.parse(avroSchemaInJson);
                    if (avroSchemaFromEmbedded.equals(avroSchemaFromJson) == false) {
                        throw new IllegalArgumentException("Embedded schema does not translate to input Avro schema: " + avroSchemaInJson);
                    }
                }
            }
        }
    }
    if (resultDataSchema == null) {
        // translationMode == TRANSLATE or no embedded schema
        DataSchemaTraverse traverse = new DataSchemaTraverse();
        traverse.traverse(dataSchema, AvroToDataSchemaConvertCallback.INSTANCE);
        // convert default values
        traverse.traverse(dataSchema, DefaultAvroToDataConvertCallback.INSTANCE);
        // make sure it can round-trip
        String dataSchemaJson = dataSchema.toString();
        resultDataSchema = DataTemplateUtil.parseSchema(dataSchemaJson);
    }
    return resultDataSchema;
}