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/
schema.go
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/
schema.go
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package generator
import (
"encoding/json"
"fmt"
)
/*
Deserialize the JSON definiton of a record and generate structs, deserializer and serializer methods.
This function only supports JSON maps at the moment, where "type" -> "record". Avro also allows for schemas
which are JSON arrays or JSON strings, but we don't currently support those as the root JSON type.
*/
func DeserializeRecordSchema(packageName string, schemaJson []byte, pkg *Package) error {
r, err := deserializeRecordDefinition(schemaJson)
if err != nil {
return err
}
r.AddStruct(pkg)
r.AddSerializer(pkg)
r.AddDeserializer(pkg)
return nil
}
/* Given a JSON record definition as a JSON encoded string, deserialize the JSON and build the record definition structs */
func deserializeRecordDefinition(schemaJson []byte) (*recordDefinition, error) {
var schema interface{}
if err := json.Unmarshal(schemaJson, &schema); err != nil {
return nil, err
}
schemaMap, ok := schema.(map[string]interface{})
if !ok {
return nil, fmt.Errorf("Invalid or unsupported schema - expected map as root JSON object")
}
return decodeRecordDefinition(schemaMap)
}
/* Given a map representing a record definition, validate the definition and build the recordDefinition struct */
func decodeRecordDefinition(schemaMap map[string]interface{}) (*recordDefinition, error) {
typeStr, err := getMapString(schemaMap, "type")
if err != nil {
return nil, err
}
if typeStr != "record" {
return nil, fmt.Errorf("Type of record must be 'record'")
}
name, err := getMapString(schemaMap, "name")
if err != nil {
return nil, err
}
fieldList, err := getMapArray(schemaMap, "fields")
if err != nil {
return nil, err
}
decodedFields := make([]field, 0)
for _, f := range fieldList {
field, ok := f.(map[string]interface{})
if !ok {
return nil, NewWrongMapValueTypeError("fields", "map[]", field)
}
fieldName, err := getMapString(field, "name")
if err != nil {
return nil, err
}
t, ok := field["type"]
if !ok {
return nil, NewRequiredMapKeyError("type")
}
def, hasDef := field["default"]
fieldStruct, err := decodeFieldDefinitionType(fieldName, t, def, hasDef)
if err != nil {
return nil, err
}
decodedFields = append(decodedFields, fieldStruct)
}
return &recordDefinition{
name: name,
fields: decodedFields,
}, nil
}
func decodeFieldDefinitionType(nameStr string, t, def interface{}, hasDef bool) (field, error) {
switch t.(type) {
case string:
typeStr := t.(string)
return createFieldStruct(nameStr, typeStr, def, hasDef)
case []interface{}:
return decodeUnionDefinition(nameStr, def, hasDef, t.([]interface{}))
case map[string]interface{}:
return decodeComplexDefinition(nameStr, t.(map[string]interface{}))
}
return nil, NewSchemaError(nameStr, NewWrongMapValueTypeError("type", "array, string, map", t))
}
func decodeUnionDefinition(nameStr string, def interface{}, hasDef bool, fieldList []interface{}) (field, error) {
unionFields := make([]field, 0)
for i, f := range fieldList {
var fieldDef field
var err error
if i == 0 {
fieldDef, err = decodeFieldDefinitionType("", f, def, hasDef)
} else {
fieldDef, err = decodeFieldDefinitionType("", f, nil, false)
}
if err != nil {
return nil, err
}
unionFields = append(unionFields, fieldDef)
}
return &unionField{nameStr, hasDef, unionFields}, nil
}
func decodeComplexDefinition(nameStr string, typeMap map[string]interface{}) (field, error) {
typeStr, err := getMapString(typeMap, "type")
if err != nil {
return nil, NewSchemaError(nameStr, err)
}
switch typeStr {
case "array":
items, ok := typeMap["items"]
if !ok {
return nil, NewSchemaError(nameStr, NewRequiredMapKeyError("items"))
}
fieldType, err := decodeFieldDefinitionType("", items, nil, false)
if err != nil {
return nil, NewSchemaError(nameStr, err)
}
return &arrayField{nameStr, fieldType}, nil
case "map":
values, ok := typeMap["values"]
if !ok {
return nil, NewSchemaError(nameStr, NewRequiredMapKeyError("values"))
}
fieldType, err := decodeFieldDefinitionType("", values, nil, false)
if err != nil {
return nil, NewSchemaError(nameStr, err)
}
return &mapField{nameStr, fieldType}, nil
case "enum":
symbolSlice, err := getMapArray(typeMap, "symbols")
if err != nil {
return nil, NewSchemaError(nameStr, err)
}
symbolStr, ok := interfaceSliceToStringSlice(symbolSlice)
if !ok {
return nil, NewSchemaError(nameStr, fmt.Errorf("'symbols' must be an array of strings"))
}
typeNameStr, err := getMapString(typeMap, "name")
if err != nil {
return nil, NewSchemaError(nameStr, err)
}
return &enumField{nameStr, typeNameStr, "", false, symbolStr}, nil
case "fixed":
size, err := getMapFloat(typeMap, "size")
if err != nil {
return nil, NewSchemaError(nameStr, err)
}
typeNameStr, err := getMapString(typeMap, "name")
if err != nil {
return nil, NewSchemaError(nameStr, err)
}
return &fixedField{nameStr, typeNameStr, nil, false, int(size)}, nil
case "record":
def, err := decodeRecordDefinition(typeMap)
if err != nil {
return nil, NewSchemaError(nameStr, err)
}
return &recordField{nameStr, def.GoType(), def}, nil
default:
return nil, NewSchemaError(nameStr, fmt.Errorf("Unknown type name %v", typeStr))
}
}
func createFieldStruct(nameStr, typeStr string, def interface{}, hasDef bool) (field, error) {
switch typeStr {
case "string":
var defStr string
var ok bool
if hasDef {
defStr, ok = def.(string)
if !ok {
return nil, fmt.Errorf("Default value must be string type")
}
}
return &stringField{nameStr, defStr, hasDef}, nil
case "int":
var defInt int32
if hasDef {
defFloat, ok := def.(float64)
if !ok {
return nil, fmt.Errorf("Default must be float type")
}
defInt = int32(defFloat)
}
return &intField{nameStr, defInt, hasDef}, nil
case "long":
var defInt int64
if hasDef {
defFloat, ok := def.(float64)
if !ok {
return nil, fmt.Errorf("Field %q default must be float type", nameStr)
}
defInt = int64(defFloat)
}
return &longField{nameStr, defInt, hasDef}, nil
case "float":
var defFloat float64
var ok bool
if hasDef {
defFloat, ok = def.(float64)
if !ok {
return nil, fmt.Errorf("Field %q default must be float type", nameStr)
}
}
return &floatField{nameStr, float32(defFloat), hasDef}, nil
case "double":
var defFloat float64
var ok bool
if hasDef {
defFloat, ok = def.(float64)
if !ok {
return nil, fmt.Errorf("Field %q default must be float type", nameStr)
}
}
return &doubleField{nameStr, defFloat, hasDef}, nil
case "boolean":
var defBool bool
var ok bool
if hasDef {
defBool, ok = def.(bool)
if !ok {
return nil, fmt.Errorf("Field %q default must be bool type", nameStr)
}
}
return &boolField{nameStr, defBool, hasDef}, nil
case "bytes":
var defBytes []byte
if hasDef {
defString, ok := def.(string)
if !ok {
return nil, fmt.Errorf("Field %q default must be string type", nameStr)
}
defBytes = []byte(defString)
}
return &bytesField{nameStr, defBytes, hasDef}, nil
case "null":
return &nullField{nameStr, hasDef}, nil
default:
return &recordField{nameStr, typeStr, nil}, nil
}
}