Added Two Way Handling for Standard Json

codec.go

@@ -103,11 +103,98 @@ func NewCodec(schemaSpecification string) (*Codec, error) {
 	})
 }
 
+// NewCodecForStandardJSON returns a codec that uses a special union
+// processing code that allows normal json to be ingested via an
+// avro schema, by inferring the "type" intended for union types.
+//
+// This is the one-way code to get such json into the avro system
+// and the deserialization is not supported in this codec - its
+// json into avro-json one-way and one-way only for this codec.
+//
+// The "type" inference is done by using the types specified as
+// potentially acceptable types for the union, and trying to
+// unpack the incomin json into each of the specified types for
+// the union type. See union.go +/Standard JSON/ for a general
+// description of the problem and details of the solution
+// are in union.go +/nativeAvroFromTextualJson/
+//
+// For a general description of a codex seen the comment for NewCodec
+// above.
+//
+// The following is the exact same schema used in the above
+// code for NewCodec:
+//
+//     codec, err := goavro.NewCodecForStandardJSON(`
+//         {
+//           "type": "record",
+//           "name": "LongList",
+//           "fields" : [
+//             {"name": "next", "type": ["null", "LongList"], "default": null}
+//           ]
+//         }`)
+//     if err != nil {
+//             fmt.Println(err)
+//     }
+//
+// The above will take json of this sort:
+//
+// {"next": null}
+//
+// {"next":{"next":null}}
+//
+// {"next":{"next":{"next":null}}}
+//
+// For more examples see the test cases in union_test.go
 func NewCodecForStandardJSON(schemaSpecification string) (*Codec, error) {
 	return NewCodecFrom(schemaSpecification, &codecBuilder{
 		buildCodecForTypeDescribedByMap,
 		buildCodecForTypeDescribedByString,
-		buildCodecForTypeDescribedBySliceJSON,
+		buildCodecForTypeDescribedBySliceOneWayJson,
+	})
+}
+
+// NewCodecForStandardJSONOneWay is an alias for NewCodecForStandardJSON
+// added to make the transition to two-way json handling more smooth
+//
+// This will unambiguously provide OneWay avro encoding for standard
+// internet json. This takes in internet json, and brings it into
+// the avro world, but the deserialization retains the unique
+// form of normal avro-friendly json where unions have their
+// types types specified in stream like this example from
+// the official docs // https://avro.apache.org/docs/1.11.1/api/c/
+//
+// `{"string": "Follow your bliss."}`
+//
+// To be clear this means the incoming json string:
+//
+// "Follow your bliss."
+//
+// would deserialize according to the avro-json expectations to:
+//
+// `{"string": "Follow your bliss."}`
+//
+// To get full two-way support see the below NewCodecForStandardJSONFull
+func NewCodecForStandardJSONOneWay(schemaSpecification string) (*Codec, error) {
+	return NewCodecForStandardJSON(schemaSpecification)
+}
+
+// NewCodecForStandardJSONFull provides full serialization/deserialization
+// for json that meets the expectations of regular internet json, viewed as
+// something distinct from avro-json which has special handling for union
+// types.  For details see the above comments.
+//
+// With this `codec` you can expect to see a json string like this:
+//
+// "Follow your bliss."
+//
+// to deserialize into the same json structure
+//
+// "Follow your bliss."
+func NewCodecForStandardJSONFull(schemaSpecification string) (*Codec, error) {
+	return NewCodecFrom(schemaSpecification, &codecBuilder{
+		buildCodecForTypeDescribedByMap,
+		buildCodecForTypeDescribedByString,
+		buildCodecForTypeDescribedBySliceTwoWayJson,
 	})
 }
 

go.mod

@@ -2,4 +2,7 @@ module github.com/linkedin/goavro/v2
 
 go 1.12
 
-require github.com/golang/snappy v0.0.1
+require (
+	github.com/golang/snappy v0.0.1
+	github.com/stretchr/testify v1.7.5
+)

go.sum

@@ -1,2 +1,16 @@
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/golang/snappy v0.0.1 h1:Qgr9rKW7uDUkrbSmQeiDsGa8SjGyCOGtuasMWwvp2P4=
 github.com/golang/snappy v0.0.1/go.mod h1:/XxbfmMg8lxefKM7IXC3fBNl/7bRcc72aCRzEWrmP2Q=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/objx v0.4.0/go.mod h1:YvHI0jy2hoMjB+UWwv71VJQ9isScKT/TqJzVSSt89Yw=
+github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+github.com/stretchr/testify v1.7.5 h1:s5PTfem8p8EbKQOctVV53k6jCJt3UX4IEJzwh+C324Q=
+github.com/stretchr/testify v1.7.5/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

text_test.go

@@ -11,9 +11,12 @@ package goavro
 
 import (
 	"bytes"
+	"encoding/json"
 	"fmt"
 	"math"
 	"testing"
+
+	"github.com/stretchr/testify/assert"
 )
 
 func testTextDecodeFail(t *testing.T, schema string, buf []byte, errorMessage string) {
@@ -63,18 +66,56 @@ func testTextDecodePass(t *testing.T, schema string, datum interface{}, encoded
 	}
 	toNativeAndCompare(t, schema, datum, encoded, codec)
 }
-func testJSONDecodePass(t *testing.T, schema string, datum interface{}, encoded []byte) {
+func testJsonDecodePass(t *testing.T, schema string, datum interface{}, encoded []byte) {
 	t.Helper()
 	codec, err := NewCodecFrom(schema, &codecBuilder{
 		buildCodecForTypeDescribedByMap,
 		buildCodecForTypeDescribedByString,
-		buildCodecForTypeDescribedBySliceJSON,
+		buildCodecForTypeDescribedBySliceOneWayJson,
 	})
 	if err != nil {
 		t.Fatalf("schema: %s; %s", schema, err)
 	}
 	toNativeAndCompare(t, schema, datum, encoded, codec)
 }
+func testNativeToTextualJsonPass(t *testing.T, schema string, datum interface{}, encoded []byte) {
+	t.Helper()
+	codec, err := NewCodecFrom(schema, &codecBuilder{
+		buildCodecForTypeDescribedByMap,
+		buildCodecForTypeDescribedByString,
+		buildCodecForTypeDescribedBySliceTwoWayJson,
+	})
+	if err != nil {
+		t.Fatalf("schema: %s; %s", schema, err)
+	}
+	toTextualAndCompare(t, schema, datum, encoded, codec)
+}
+
+func toTextualAndCompare(t *testing.T, schema string, datum interface{}, expected []byte, codec *Codec) {
+	t.Helper()
+	decoded, err := codec.TextualFromNative(nil, datum)
+	if err != nil {
+		t.Fatalf("schema: %s; %s", schema, err)
+	}
+
+	// do extra stuff to to the challenge equality of maps
+	var want interface{}
+
+	if err := json.Unmarshal(expected, &want); err != nil {
+		t.Errorf("Could not unmarshal the expected data into a go struct:%#v:", string(expected))
+	}
+
+	var got interface{}
+
+	if err := json.Unmarshal(decoded, &got); err != nil {
+		t.Errorf("Could not unmarshal the received data into a go struct:%#v:", string(decoded))
+	}
+
+	if !assert.Equal(t, want, got) {
+		t.Errorf("GOT: %v; WANT: %v", string(decoded), string(expected))
+	}
+}
+
 func toNativeAndCompare(t *testing.T, schema string, datum interface{}, encoded []byte, codec *Codec) {
 	t.Helper()
 	decoded, remaining, err := codec.NativeFromTextual(encoded)

union.go

@@ -87,7 +87,7 @@ func makeCodecInfo(st map[string]*Codec, enclosingNamespace string, schemaArray
 
 }
 
-func nativeFromBinary(cr *codecInfo) func(buf []byte) (interface{}, []byte, error) {
+func unionNativeFromBinary(cr *codecInfo) func(buf []byte) (interface{}, []byte, error) {
 
 	return func(buf []byte) (interface{}, []byte, error) {
 		var decoded interface{}
@@ -114,7 +114,7 @@ func nativeFromBinary(cr *codecInfo) func(buf []byte) (interface{}, []byte, erro
 		return Union(cr.allowedTypes[index], decoded), buf, nil
 	}
 }
-func binaryFromNative(cr *codecInfo) func(buf []byte, datum interface{}) ([]byte, error) {
+func unionBinaryFromNative(cr *codecInfo) func(buf []byte, datum interface{}) ([]byte, error) {
 	return func(buf []byte, datum interface{}) ([]byte, error) {
 		switch v := datum.(type) {
 		case nil:
@@ -141,7 +141,7 @@ func binaryFromNative(cr *codecInfo) func(buf []byte, datum interface{}) ([]byte
 		return nil, fmt.Errorf("cannot encode binary union: non-nil Union values ought to be specified with Go map[string]interface{}, with single key equal to type name, and value equal to datum value: %v; received: %T", cr.allowedTypes, datum)
 	}
 }
-func nativeFromTextual(cr *codecInfo) func(buf []byte) (interface{}, []byte, error) {
+func unionNativeFromTextual(cr *codecInfo) func(buf []byte) (interface{}, []byte, error) {
 	return func(buf []byte) (interface{}, []byte, error) {
 		if len(buf) >= 4 && bytes.Equal(buf[:4], []byte("null")) {
 			if _, ok := cr.indexFromName["null"]; ok {
@@ -159,7 +159,7 @@ func nativeFromTextual(cr *codecInfo) func(buf []byte) (interface{}, []byte, err
 		return datum, buf, nil
 	}
 }
-func textualFromNative(cr *codecInfo) func(buf []byte, datum interface{}) ([]byte, error) {
+func unionTextualFromNative(cr *codecInfo) func(buf []byte, datum interface{}) ([]byte, error) {
 	return func(buf []byte, datum interface{}) ([]byte, error) {
 		switch v := datum.(type) {
 		case nil:
@@ -196,6 +196,37 @@ func textualFromNative(cr *codecInfo) func(buf []byte, datum interface{}) ([]byt
 		return nil, fmt.Errorf("cannot encode textual union: non-nil values ought to be specified with Go map[string]interface{}, with single key equal to type name, and value equal to datum value: %v; received: %T", cr.allowedTypes, datum)
 	}
 }
+func textualJsonFromNativeAvro(cr *codecInfo) func(buf []byte, datum interface{}) ([]byte, error) {
+	return func(buf []byte, datum interface{}) ([]byte, error) {
+		switch v := datum.(type) {
+		case nil:
+			_, ok := cr.indexFromName["null"]
+			if !ok {
+				return nil, fmt.Errorf("cannot encode textual union: no member schema types support datum: allowed types: %v; received: %T", cr.allowedTypes, datum)
+			}
+			return append(buf, "null"...), nil
+		case map[string]interface{}:
+			if len(v) != 1 {
+				return nil, fmt.Errorf("cannot encode textual union: non-nil Union values ought to be specified with Go map[string]interface{}, with single key equal to type name, and value equal to datum value: %v; received: %T", cr.allowedTypes, datum)
+			}
+			// will execute exactly once
+			for key, value := range v {
+				index, ok := cr.indexFromName[key]
+				if !ok {
+					return nil, fmt.Errorf("cannot encode textual union: no member schema types support datum: allowed types: %v; received: %T", cr.allowedTypes, datum)
+				}
+				var err error
+				c := cr.codecFromIndex[index]
+				buf, err = c.textualFromNative(buf, value)
+				if err != nil {
+					return nil, fmt.Errorf("cannot encode textual union: %s", err)
+				}
+				return buf, nil
+			}
+		}
+		return nil, fmt.Errorf("cannot encode textual union: non-nil values ought to be specified with Go map[string]interface{}, with single key equal to type name, and value equal to datum value: %v; received: %T", cr.allowedTypes, datum)
+	}
+}
 func buildCodecForTypeDescribedBySlice(st map[string]*Codec, enclosingNamespace string, schemaArray []interface{}, cb *codecBuilder) (*Codec, error) {
 	if len(schemaArray) == 0 {
 		return nil, errors.New("Union ought to have one or more members")
@@ -213,10 +244,10 @@ func buildCodecForTypeDescribedBySlice(st map[string]*Codec, enclosingNamespace
 		schemaOriginal: cr.codecFromIndex[0].typeName.fullName,
 
 		typeName:          &name{"union", nullNamespace},
-		nativeFromBinary:  nativeFromBinary(&cr),
-		binaryFromNative:  binaryFromNative(&cr),
-		nativeFromTextual: nativeFromTextual(&cr),
-		textualFromNative: textualFromNative(&cr),
+		nativeFromBinary:  unionNativeFromBinary(&cr),
+		binaryFromNative:  unionBinaryFromNative(&cr),
+		nativeFromTextual: unionNativeFromTextual(&cr),
+		textualFromNative: unionTextualFromNative(&cr),
 	}
 	return rv, nil
 }
@@ -246,7 +277,31 @@ func buildCodecForTypeDescribedBySlice(st map[string]*Codec, enclosingNamespace
 // and then it will remain avro-json object
 // avro data is not serialized back into standard json
 // the data goes to avro-json and stays that way
-func buildCodecForTypeDescribedBySliceJSON(st map[string]*Codec, enclosingNamespace string, schemaArray []interface{}, cb *codecBuilder) (*Codec, error) {
+func buildCodecForTypeDescribedBySliceOneWayJson(st map[string]*Codec, enclosingNamespace string, schemaArray []interface{}, cb *codecBuilder) (*Codec, error) {
+	if len(schemaArray) == 0 {
+		return nil, errors.New("Union ought to have one or more members")
+	}
+
+	cr, err := makeCodecInfo(st, enclosingNamespace, schemaArray, cb)
+	if err != nil {
+		return nil, err
+	}
+
+	rv := &Codec{
+		// NOTE: To support record field default values, union schema set to the
+		// type name of first member
+		// TODO: add/change to schemaCanonical below
+		schemaOriginal: cr.codecFromIndex[0].typeName.fullName,
+
+		typeName:          &name{"union", nullNamespace},
+		nativeFromBinary:  unionNativeFromBinary(&cr),
+		binaryFromNative:  unionBinaryFromNative(&cr),
+		nativeFromTextual: nativeAvroFromTextualJson(&cr),
+		textualFromNative: unionTextualFromNative(&cr),
+	}
+	return rv, nil
+}
+func buildCodecForTypeDescribedBySliceTwoWayJson(st map[string]*Codec, enclosingNamespace string, schemaArray []interface{}, cb *codecBuilder) (*Codec, error) {
 	if len(schemaArray) == 0 {
 		return nil, errors.New("Union ought to have one or more members")
 	}
@@ -263,10 +318,10 @@ func buildCodecForTypeDescribedBySliceJSON(st map[string]*Codec, enclosingNamesp
 		schemaOriginal: cr.codecFromIndex[0].typeName.fullName,
 
 		typeName:          &name{"union", nullNamespace},
-		nativeFromBinary:  nativeFromBinary(&cr),
-		binaryFromNative:  binaryFromNative(&cr),
+		nativeFromBinary:  unionNativeFromBinary(&cr),
+		binaryFromNative:  unionBinaryFromNative(&cr),
 		nativeFromTextual: nativeAvroFromTextualJson(&cr),
-		textualFromNative: textualFromNative(&cr),
+		textualFromNative: textualJsonFromNativeAvro(&cr),
 	}
 	return rv, nil
 }