mirror of https://github.com/jackc/pgx.git
add RowTo(AddrOf)StructByNameLax
Audi P. Risa P
Jack Christensen
parent
e9d64ec29d
commit
193bab416f
90
rows.go
90
rows.go
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@ -578,7 +578,6 @@ func (rs *namedStructRowScanner) ScanRow(rows Rows) error {
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dstElemValue := dstValue.Elem()
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scanTargets, err := rs.appendScanTargets(dstElemValue, nil, rows.FieldDescriptions())
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if err != nil {
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return err
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}
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@ -647,3 +646,92 @@ func (rs *namedStructRowScanner) appendScanTargets(dstElemValue reflect.Value, s
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return scanTargets, err
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}
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// RowToStructByNameLax returns a T scanned from row. T must be a struct. T must have greater than or equal number of named public
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// fields as row has fields. The row and T fields will by matched by name. The match is case-insensitive. The database
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// column name can be overridden with a "db" struct tag. If the "db" struct tag is "-" then the field will be ignored.
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func RowToStructByNameLax[T any](row CollectableRow) (T, error) {
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var value T
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err := row.Scan(&namedStructRowLaxScanner{ptrToStruct: &value})
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return value, err
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}
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// RowToAddrOfStructByNameLax returns the address of a T scanned from row. T must be a struct. T must have greater than or
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// equal number of named public fields as row has fields. The row and T fields will by matched by name. The match is
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// case-insensitive. The database column name can be overridden with a "db" struct tag. If the "db" struct tag is "-"
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// then the field will be ignored.
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func RowToAddrOfStructByNameLax[T any](row CollectableRow) (*T, error) {
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var value T
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err := row.Scan(&namedStructRowLaxScanner{ptrToStruct: &value})
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return &value, err
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}
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type namedStructRowLaxScanner struct {
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ptrToStruct any
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}
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func (rs *namedStructRowLaxScanner) ScanRow(rows Rows) error {
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dst := rs.ptrToStruct
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dstValue := reflect.ValueOf(dst)
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if dstValue.Kind() != reflect.Ptr {
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return fmt.Errorf("dst not a pointer")
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}
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dstElemValue := dstValue.Elem()
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scanTargets, err := rs.appendScanTargets(dstElemValue, nil, rows.FieldDescriptions())
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if err != nil {
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return err
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}
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for i, t := range scanTargets {
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if t == nil {
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return fmt.Errorf("struct doesn't have corresponding row field %s", rows.FieldDescriptions()[i].Name)
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}
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}
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return rows.Scan(scanTargets...)
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}
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func (rs *namedStructRowLaxScanner) appendScanTargets(dstElemValue reflect.Value, scanTargets []any, fldDescs []pgconn.FieldDescription) ([]any, error) {
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var err error
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dstElemType := dstElemValue.Type()
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if scanTargets == nil {
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scanTargets = make([]any, len(fldDescs))
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}
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for i := 0; i < dstElemType.NumField(); i++ {
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sf := dstElemType.Field(i)
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if sf.PkgPath != "" && !sf.Anonymous {
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// Field is unexported, skip it.
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continue
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}
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// Handle anoymous struct embedding, but do not try to handle embedded pointers.
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if sf.Anonymous && sf.Type.Kind() == reflect.Struct {
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scanTargets, err = rs.appendScanTargets(dstElemValue.Field(i), scanTargets, fldDescs)
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if err != nil {
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return nil, err
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}
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} else {
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dbTag, dbTagPresent := sf.Tag.Lookup(structTagKey)
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if dbTagPresent {
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dbTag = strings.Split(dbTag, ",")[0]
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}
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if dbTag == "-" {
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// Field is ignored, skip it.
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continue
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}
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colName := dbTag
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if !dbTagPresent {
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colName = sf.Name
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}
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fpos := fieldPosByName(fldDescs, colName)
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if fpos == -1 {
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continue
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}
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scanTargets[fpos] = dstElemValue.Field(i).Addr().Interface()
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}
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}
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return scanTargets, err
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}
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161
rows_test.go
161
rows_test.go
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@ -635,3 +635,164 @@ insert into products (name, price) values
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// Fries: $5
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// Soft Drink: $3
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}
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func TestRowToStructByNameLax(t *testing.T) {
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type person struct {
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Last string
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First string
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Age int32
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Ignore bool `db:"-"`
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}
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defaultConnTestRunner.RunTest(context.Background(), t, func(ctx context.Context, t testing.TB, conn *pgx.Conn) {
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rows, _ := conn.Query(ctx, `select 'John' as first, 'Smith' as last, n as age from generate_series(0, 9) n`)
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slice, err := pgx.CollectRows(rows, pgx.RowToStructByNameLax[person])
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assert.NoError(t, err)
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assert.Len(t, slice, 10)
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for i := range slice {
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assert.Equal(t, "Smith", slice[i].Last)
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assert.Equal(t, "John", slice[i].First)
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assert.EqualValues(t, i, slice[i].Age)
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}
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// check missing fields in a returned row
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rows, _ = conn.Query(ctx, `select 'John' as first, n as age from generate_series(0, 9) n`)
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slice, err = pgx.CollectRows(rows, pgx.RowToStructByNameLax[person])
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assert.NoError(t, err)
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assert.Len(t, slice, 10)
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for i := range slice {
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assert.Equal(t, "John", slice[i].First)
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assert.EqualValues(t, i, slice[i].Age)
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}
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// check extra fields in a returned row
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rows, _ = conn.Query(ctx, `select 'John' as first, 'Smith' as last, n as age, null as ignore from generate_series(0, 9) n`)
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_, err = pgx.CollectRows(rows, pgx.RowToAddrOfStructByNameLax[person])
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assert.ErrorContains(t, err, "struct doesn't have corresponding row field ignore")
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// check missing fields in a destination struct
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rows, _ = conn.Query(ctx, `select 'Smith' as last, 'D.' as middle, n as age from generate_series(0, 9) n`)
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_, err = pgx.CollectRows(rows, pgx.RowToAddrOfStructByNameLax[person])
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assert.ErrorContains(t, err, "struct doesn't have corresponding row field middle")
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// check ignored fields in a destination struct
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rows, _ = conn.Query(ctx, `select 'Smith' as last, n as age, null as ignore from generate_series(0, 9) n`)
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_, err = pgx.CollectRows(rows, pgx.RowToAddrOfStructByNameLax[person])
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assert.ErrorContains(t, err, "struct doesn't have corresponding row field ignore")
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})
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}
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func TestRowToStructByNameLaxEmbeddedStruct(t *testing.T) {
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type Name struct {
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Last string `db:"last_name"`
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First string `db:"first_name"`
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}
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type person struct {
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Ignore bool `db:"-"`
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Name
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Age int32
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}
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defaultConnTestRunner.RunTest(context.Background(), t, func(ctx context.Context, t testing.TB, conn *pgx.Conn) {
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rows, _ := conn.Query(ctx, `select 'John' as first_name, 'Smith' as last_name, n as age from generate_series(0, 9) n`)
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slice, err := pgx.CollectRows(rows, pgx.RowToStructByNameLax[person])
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assert.NoError(t, err)
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assert.Len(t, slice, 10)
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for i := range slice {
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assert.Equal(t, "Smith", slice[i].Name.Last)
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assert.Equal(t, "John", slice[i].Name.First)
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assert.EqualValues(t, i, slice[i].Age)
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}
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// check missing fields in a returned row
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rows, _ = conn.Query(ctx, `select 'John' as first_name, n as age from generate_series(0, 9) n`)
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slice, err = pgx.CollectRows(rows, pgx.RowToStructByNameLax[person])
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assert.NoError(t, err)
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assert.Len(t, slice, 10)
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for i := range slice {
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assert.Equal(t, "John", slice[i].Name.First)
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assert.EqualValues(t, i, slice[i].Age)
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}
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// check extra fields in a returned row
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rows, _ = conn.Query(ctx, `select 'John' as first_name, 'Smith' as last_name, n as age, null as ignore from generate_series(0, 9) n`)
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_, err = pgx.CollectRows(rows, pgx.RowToAddrOfStructByNameLax[person])
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assert.ErrorContains(t, err, "struct doesn't have corresponding row field ignore")
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// check missing fields in a destination struct
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rows, _ = conn.Query(ctx, `select 'Smith' as last_name, 'D.' as middle_name, n as age from generate_series(0, 9) n`)
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_, err = pgx.CollectRows(rows, pgx.RowToAddrOfStructByNameLax[person])
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assert.ErrorContains(t, err, "struct doesn't have corresponding row field middle_name")
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// check ignored fields in a destination struct
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rows, _ = conn.Query(ctx, `select 'Smith' as last_name, n as age, null as ignore from generate_series(0, 9) n`)
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_, err = pgx.CollectRows(rows, pgx.RowToAddrOfStructByNameLax[person])
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assert.ErrorContains(t, err, "struct doesn't have corresponding row field ignore")
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})
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}
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func ExampleRowToStructByNameLax() {
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ctx, cancel := context.WithTimeout(context.Background(), 15*time.Second)
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defer cancel()
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conn, err := pgx.Connect(ctx, os.Getenv("PGX_TEST_DATABASE"))
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if err != nil {
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fmt.Printf("Unable to establish connection: %v", err)
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return
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}
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if conn.PgConn().ParameterStatus("crdb_version") != "" {
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// Skip test / example when running on CockroachDB. Since an example can't be skipped fake success instead.
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fmt.Println(`Cheeseburger: $10
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Fries: $5
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Soft Drink: $3`)
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return
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}
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// Setup example schema and data.
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_, err = conn.Exec(ctx, `
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create temporary table products (
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id int primary key generated by default as identity,
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name varchar(100) not null,
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price int not null
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);
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insert into products (name, price) values
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('Cheeseburger', 10),
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('Double Cheeseburger', 14),
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('Fries', 5),
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('Soft Drink', 3);
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`)
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if err != nil {
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fmt.Printf("Unable to setup example schema and data: %v", err)
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return
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}
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type product struct {
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ID int32
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Name string
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Type string
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Price int32
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}
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rows, _ := conn.Query(ctx, "select * from products where price < $1 order by price desc", 12)
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products, err := pgx.CollectRows(rows, pgx.RowToStructByNameLax[product])
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if err != nil {
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fmt.Printf("CollectRows error: %v", err)
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return
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}
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for _, p := range products {
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fmt.Printf("%s: $%d\n", p.Name, p.Price)
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}
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// Output:
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// Cheeseburger: $10
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// Fries: $5
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// Soft Drink: $3
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}
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