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GODRIVER-3427 Add a global "omitempty" flag. #1953

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merged 2 commits into from
Mar 4, 2025
Merged

GODRIVER-3427 Add a global "omitempty" flag. #1953

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0e6dc09
GODRIVER-3427 Add a global "omitempty" flag.
qingyang-hu Feb 20, 2025
294c208
update tests
qingyang-hu Feb 28, 2025
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1 change: 1 addition & 0 deletions bson/bsoncodec.go
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Expand Up @@ -88,6 +88,7 @@ type EncodeContext struct {
nilSliceAsEmpty bool
nilByteSliceAsEmpty bool
omitZeroStruct bool
omitEmpty bool
useJSONStructTags bool
}

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9 changes: 8 additions & 1 deletion bson/encoder.go
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Expand Up @@ -108,14 +108,21 @@ func (e *Encoder) NilByteSliceAsEmpty() {
// TODO struct fields once the logic is updated to also inspect private struct fields.

// OmitZeroStruct causes the Encoder to consider the zero value for a struct (e.g. MyStruct{})
// as empty and omit it from the marshaled BSON when the "omitempty" struct tag option is set.
// as empty and omit it from the marshaled BSON when the "omitempty" struct tag option is set
// or the OmitEmpty() method is called.
//
// Note that the Encoder only examines exported struct fields when determining if a struct is the
// zero value. It considers pointers to a zero struct value (e.g. &MyStruct{}) not empty.
func (e *Encoder) OmitZeroStruct() {
e.ec.omitZeroStruct = true
}

// OmitEmpty causes the Encoder to omit empty values from the marshaled BSON as the "omitempty"
// struct tag option is set.
func (e *Encoder) OmitEmpty() {
e.ec.omitEmpty = true
}

// UseJSONStructTags causes the Encoder to fall back to using the "json" struct tag if a "bson"
// struct tag is not specified.
func (e *Encoder) UseJSONStructTags() {
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13 changes: 13 additions & 0 deletions bson/encoder_test.go
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Expand Up @@ -248,6 +248,19 @@ func TestEncoderConfiguration(t *testing.T) {
}{},
want: bsoncore.NewDocumentBuilder().Build(),
},
// Test that OmitZeroStruct omits empty structs from the marshaled document if
// OmitEmpty is also set.
{
description: "OmitEmpty",
configure: func(enc *Encoder) {
enc.OmitZeroStruct()
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Suggest renaming this test "OmitEmpty with non-zeroer struct".

Additionally, we need to creating a new test where enc.OmitZeroStruct() is not used in the configuration. The new test should include the types referenced in the documentation and should be called "OmitEmpty":

Numbers, booleans, and strings are considered empty if their value is equal to the zero value for the type (i.e. 0 for numbers, false for booleans, and "" for strings). Slices, maps, and arrays are considered empty if they are of length zero. Interfaces and pointers are considered empty if their value is nil. By default, structs are only considered empty if the struct type implements bsoncodec.Zeroer and the IsZero method returns true. Struct types that do not implement bsoncodec.Zeroer are never considered empty and will be marshaled as embedded documents.

type zeroer struct {
	MyString string
}

func (zeroer) IsZero() bool {
	return true
}

var _ bson.Zeroer = zeroer{}

type myStruct struct {
	Zero    zeroer
	I64     int64
	F64     float64
	String  string
	Boolean bool
	Array   []int
	Map     map[string]int
	Bytes   []byte
	Time    time.Time
	Pointer *int
}

enc.OmitEmpty()
},
input: struct {
Zero zeroStruct
}{},
want: bsoncore.NewDocumentBuilder().Build(),
},
// Test that UseJSONStructTags causes the Encoder to fall back to "json" struct tags if
// "bson" struct tags are not available.
{
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4 changes: 4 additions & 0 deletions bson/struct_codec.go
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Expand Up @@ -118,6 +118,10 @@ func (sc *structCodec) EncodeValue(ec EncodeContext, vw ValueWriter, val reflect
}
}

if ec.omitEmpty {
desc.omitEmpty = true
}

desc.encoder, rv, err = lookupElementEncoder(ec, desc.encoder, rv)

if err != nil && !errors.Is(err, errInvalidValue) {
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13 changes: 13 additions & 0 deletions internal/integration/client_test.go
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Expand Up @@ -956,6 +956,19 @@ func TestClient_BSONOptions(t *testing.T) {
want: &bson.D{},
wantRaw: bson.Raw(bsoncore.NewDocumentBuilder().Build()),
},
{
name: "OmitEmpty",
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Suggest renaming this test "OmitEmpty with non-zeroer struct".

bsonOpts: &options.BSONOptions{
OmitZeroStruct: true,
OmitEmpty: true,
},
doc: struct {
X jsonTagsTest `bson:"x"`
}{},
decodeInto: func() interface{} { return &bson.D{} },
want: &bson.D{},
wantRaw: bson.Raw(bsoncore.NewDocumentBuilder().Build()),
},
{
name: "StringifyMapKeysWithFmt",
bsonOpts: &options.BSONOptions{
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3 changes: 3 additions & 0 deletions mongo/mongo.go
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Expand Up @@ -83,6 +83,9 @@ func getEncoder(
if opts.OmitZeroStruct {
enc.OmitZeroStruct()
}
if opts.OmitEmpty {
enc.OmitEmpty()
}
if opts.StringifyMapKeysWithFmt {
enc.StringifyMapKeysWithFmt()
}
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5 changes: 4 additions & 1 deletion mongo/options/clientoptions.go
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Expand Up @@ -182,9 +182,12 @@ type BSONOptions struct {

// OmitZeroStruct causes the driver to consider the zero value for a struct
// (e.g. MyStruct{}) as empty and omit it from the marshaled BSON when the
// "omitempty" struct tag option is set.
// "omitempty" struct tag option or the "OmitEmpty" field is set.
OmitZeroStruct bool

// OmitEmpty causes the driver to omit empty values from the marshaled BSON.
OmitEmpty bool

// StringifyMapKeysWithFmt causes the driver to convert Go map keys to BSON
// document field name strings using fmt.Sprint instead of the default
// string conversion logic.
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