joellubi commented on code in PR #43679: URL: https://github.com/apache/arrow/pull/43679#discussion_r1718801380
########## go/arrow/extensions/json.go: ########## @@ -0,0 +1,140 @@ +// 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 extensions + +import ( + "fmt" + "reflect" + "slices" + + "github.com/apache/arrow/go/v18/arrow" + "github.com/apache/arrow/go/v18/arrow/array" + "github.com/apache/arrow/go/v18/internal/json" + "github.com/apache/arrow/go/v18/parquet/schema" +) + +var jsonSupportedStorageTypes = []arrow.DataType{ + arrow.BinaryTypes.String, + arrow.BinaryTypes.LargeString, + arrow.BinaryTypes.StringView, +} + +// JSONType represents a UTF-8 encoded JSON string as specified in RFC8259. +type JSONType struct { + arrow.ExtensionBase +} + +// ParquetLogicalType implements CustomParquetType. +func (b *JSONType) ParquetLogicalType() schema.LogicalType { + return schema.JSONLogicalType{} +} + +// NewJSONType creates a new JSONType with the specified storage type. +// storageType must be one of String, LargeString, StringView. +func NewJSONType(storageType arrow.DataType) (*JSONType, error) { + if !slices.Contains(jsonSupportedStorageTypes, storageType) { + return nil, fmt.Errorf("unsupported storage type for JSON extension type: %s", storageType) + } + return &JSONType{ExtensionBase: arrow.ExtensionBase{Storage: storageType}}, nil +} + +func (b *JSONType) ArrayType() reflect.Type { return reflect.TypeOf(JSONArray{}) } + +func (b *JSONType) Deserialize(storageType arrow.DataType, data string) (arrow.ExtensionType, error) { + if !(data == "" || data == "{}") { + return nil, fmt.Errorf("serialized metadata for JSON extension type must be '' or '{}', found: %s", data) + } + return NewJSONType(storageType) +} + +func (b *JSONType) ExtensionEquals(other arrow.ExtensionType) bool { + return b.ExtensionName() == other.ExtensionName() && arrow.TypeEqual(b.Storage, other.StorageType()) +} + +func (b *JSONType) ExtensionName() string { return "arrow.json" } + +func (b *JSONType) Serialize() string { return "" } + +func (b *JSONType) String() string { + return fmt.Sprintf("extension<%s[storage_type=%s]>", b.ExtensionName(), b.Storage) +} + +// JSONArray is logically an array of UTF-8 encoded JSON strings. +// Its values are unmarshaled to native Go values. +type JSONArray struct { + array.ExtensionArrayBase +} + +func (a *JSONArray) String() string { + b, err := a.MarshalJSON() + if err != nil { + panic(fmt.Sprintf("failed marshal JSONArray: %s", err)) + } + + return string(b) +} + +func (a *JSONArray) Value(i int) any { + valString := a.ValueStr(i) + + var val any + if err := json.Unmarshal([]byte(valString), &val); err != nil { + panic(err) + } + + return val +} + +func (a *JSONArray) ValueStr(i int) string { + if a.IsNull(i) { + return "null" + } + + switch storage := a.Storage().(type) { + case *array.String: + return storage.Value(i) + case *array.LargeString: + return storage.Value(i) + case *array.StringView: + return storage.Value(i) + default: + panic(fmt.Sprintf("invalid JSON extension array with storage type: %s", storage)) + } Review Comment: Beautiful! I hadn't seen this interface before. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: github-unsubscr...@arrow.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
