From 2ec377350bc2d3d8aa86e46ecbb4be12715eca6c Mon Sep 17 00:00:00 2001 From: Jack Christensen Date: Sat, 5 Sep 2020 11:19:51 -0500 Subject: [PATCH] Update Rows.Scan documentation to reflect reality. Previously, the Scan documentation stated that scanning into a []byte will skip the decoding process and directly copy the raw bytes received from PostgreSQL. This has not been true for at least 2 months. It is also undesirable behavior in some cases such as a binary formatted jsonb. In that case the '1' prefix needs to be stripped to have valid JSON. If the raw bytes are desired this can easily be accomplished by scanning into pgtype.GenericBinary or using Rows.RawValues. In light of the fact that the new behavior is superior, and that it has been in place for a significant amount of time, I have decided to document the new behavior rather than change back to the old behavior. --- go.mod | 2 +- go.sum | 2 ++ rows.go | 3 +-- values_test.go | 44 ++++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 48 insertions(+), 3 deletions(-) diff --git a/go.mod b/go.mod index 5d18d577..14003102 100644 --- a/go.mod +++ b/go.mod @@ -8,7 +8,7 @@ require ( github.com/jackc/pgconn v1.6.5-0.20200821030840-fdfc783345f6 github.com/jackc/pgio v1.0.0 github.com/jackc/pgproto3/v2 v2.0.4 - github.com/jackc/pgtype v1.4.2 + github.com/jackc/pgtype v1.4.3-0.20200905161353-e7d2b057a716 github.com/jackc/puddle v1.1.2-0.20200821025810-91d0159cc97a github.com/mattn/go-colorable v0.1.6 // indirect github.com/rs/zerolog v1.15.0 diff --git a/go.sum b/go.sum index 4249eec2..a511f139 100644 --- a/go.sum +++ b/go.sum @@ -88,6 +88,8 @@ github.com/jackc/pgtype v1.4.1 h1:8PRKqCS9Nt2FQbNegoEAIlY6r/DTP2aaXyh5bAEn89g= github.com/jackc/pgtype v1.4.1/go.mod h1:JCULISAZBFGrHaOXIIFiyfzW5VY0GRitRr8NeJsrdig= github.com/jackc/pgtype v1.4.2 h1:t+6LWm5eWPLX1H5Se702JSBcirq6uWa4jiG4wV1rAWY= github.com/jackc/pgtype v1.4.2/go.mod h1:JCULISAZBFGrHaOXIIFiyfzW5VY0GRitRr8NeJsrdig= +github.com/jackc/pgtype v1.4.3-0.20200905161353-e7d2b057a716 h1:DrP52jA32liWkjCF/g3rYC1QjnRh6kvyXaZSevAtlqE= +github.com/jackc/pgtype v1.4.3-0.20200905161353-e7d2b057a716/go.mod h1:JCULISAZBFGrHaOXIIFiyfzW5VY0GRitRr8NeJsrdig= github.com/jackc/pgx/v4 v4.0.0-20190420224344-cc3461e65d96/go.mod h1:mdxmSJJuR08CZQyj1PVQBHy9XOp5p8/SHH6a0psbY9Y= github.com/jackc/pgx/v4 v4.0.0-20190421002000-1b8f0016e912/go.mod h1:no/Y67Jkk/9WuGR0JG/JseM9irFbnEPbuWV2EELPNuM= github.com/jackc/pgx/v4 v4.0.0-pre1.0.20190824185557-6972a5742186/go.mod h1:X+GQnOEnf1dqHGpw7JmHqHc1NxDoalibchSk9/RWuDc= diff --git a/rows.go b/rows.go index fe6969e8..957192f6 100644 --- a/rows.go +++ b/rows.go @@ -42,8 +42,7 @@ type Rows interface { // Scan reads the values from the current row into dest values positionally. // dest can include pointers to core types, values implementing the Scanner - // interface, []byte, and nil. []byte will skip the decoding process and directly - // copy the raw bytes received from PostgreSQL. nil will skip the value entirely. + // interface, and nil. nil will skip the value entirely. Scan(dest ...interface{}) error // Values returns the decoded row values. diff --git a/values_test.go b/values_test.go index 5884e228..5159964a 100644 --- a/values_test.go +++ b/values_test.go @@ -983,3 +983,47 @@ order by a nulls first require.NoError(t, rows.Err()) }) } + +func TestScanIntoByteSlice(t *testing.T) { + t.Parallel() + + conn := mustConnectString(t, os.Getenv("PGX_TEST_DATABASE")) + defer closeConn(t, conn) + // Success cases + for _, tt := range []struct { + name string + sql string + resultFormatCode int16 + output []byte + }{ + {"int - text", "select 42", pgx.TextFormatCode, []byte("42")}, + {"text - text", "select 'hi'", pgx.TextFormatCode, []byte("hi")}, + {"text - binary", "select 'hi'", pgx.BinaryFormatCode, []byte("hi")}, + {"json - text", "select '{}'::json", pgx.TextFormatCode, []byte("{}")}, + {"json - binary", "select '{}'::json", pgx.BinaryFormatCode, []byte("{}")}, + {"jsonb - text", "select '{}'::jsonb", pgx.TextFormatCode, []byte("{}")}, + {"jsonb - binary", "select '{}'::jsonb", pgx.BinaryFormatCode, []byte("{}")}, + } { + t.Run(tt.name, func(t *testing.T) { + var buf []byte + err := conn.QueryRow(context.Background(), tt.sql, pgx.QueryResultFormats{tt.resultFormatCode}).Scan(&buf) + require.NoError(t, err) + require.Equal(t, tt.output, buf) + }) + } + + // Failure cases + for _, tt := range []struct { + name string + sql string + err string + }{ + {"int binary", "select 42", "can't scan into dest[0]: cannot assign 42 into *[]uint8"}, + } { + t.Run(tt.name, func(t *testing.T) { + var buf []byte + err := conn.QueryRow(context.Background(), tt.sql, pgx.QueryResultFormats{pgx.BinaryFormatCode}).Scan(&buf) + require.EqualError(t, err, tt.err) + }) + } +}