Added json output format for SQL, and fixed null printing bug in CSV output

Signed-off-by: Zach Musgrave <zach@liquidata.co>

go/cmd/dolt/commands/cnfcmds/cat.go

@@ -167,7 +167,7 @@ func printConflicts(ctx context.Context, root *doltdb.RootValue, tblNames []stri
 			nullPrinter := nullprinter.NewNullPrinter(cnfRd.GetSchema())
 			fwtTr := fwt.NewAutoSizingFWTTransformer(cnfRd.GetSchema(), fwt.HashFillWhenTooLong, 1000)
 			transforms := pipeline.NewTransformCollection(
-				pipeline.NewNamedTransform(nullprinter.NULL_PRINTING_STAGE, nullPrinter.ProcessRow),
+				pipeline.NewNamedTransform(nullprinter.NullPrintingStage, nullPrinter.ProcessRow),
 				pipeline.NamedTransform{Name: "fwt", Func: fwtTr.TransformToFWT},
 			)
 

go/cmd/dolt/commands/diff.go

@@ -710,7 +710,7 @@ func buildPipeline(dArgs *diffArgs, joiner *rowconv.Joiner, ds *diff.DiffSplitte
 		nullPrinter := nullprinter.NewNullPrinter(untypedUnionSch)
 		fwtTr := fwt.NewAutoSizingFWTTransformer(untypedUnionSch, fwt.HashFillWhenTooLong, 1000)
 		transforms.AppendTransforms(
-			pipeline.NewNamedTransform(nullprinter.NULL_PRINTING_STAGE, nullPrinter.ProcessRow),
+			pipeline.NewNamedTransform(nullprinter.NullPrintingStage, nullPrinter.ProcessRow),
 			pipeline.NamedTransform{Name: fwtStageName, Func: fwtTr.TransformToFWT},
 		)
 	}

go/cmd/dolt/commands/sql.go

@@ -19,6 +19,7 @@ import (
 	"bytes"
 	"context"
 	"fmt"
+	"github.com/liquidata-inc/dolt/go/libraries/doltcore/table/typed/json"
 	"io"
 	"os"
 	"path/filepath"
@@ -452,6 +453,8 @@ func getFormat(format string) (resultFormat, errhand.VerboseError) {
 		return formatTabular, nil
 	case "csv":
 		return formatCsv, nil
+	case "json":
+		return formatJson, nil
 	default:
 		return formatTabular, errhand.BuildDError("Invalid argument for --result-format. Valid values are tabular,csv").Build()
 	}
@@ -1051,6 +1054,7 @@ type resultFormat byte
 const (
 	formatTabular resultFormat = iota
 	formatCsv
+	formatJson
 )
 
 type sqlEngine struct {
@@ -1180,10 +1184,15 @@ func (se *sqlEngine) prettyPrintResults(ctx context.Context, sqlSch sql.Schema,
 		}
 	}()
 
-	nullPrinter := nullprinter.NewNullPrinter(untypedSch)
-	p.AddStage(pipeline.NewNamedTransform(nullprinter.NULL_PRINTING_STAGE, nullPrinter.ProcessRow))
+	// Parts of the pipeline depend on the output format, such as how we print null values and whether we pad strings.
+	switch se.resultFormat {
+	case formatCsv:
+		nullPrinter := nullprinter.NewNullPrinterWithNullString(untypedSch, "")
+		p.AddStage(pipeline.NewNamedTransform(nullprinter.NullPrintingStage, nullPrinter.ProcessRow))
 
-	if se.resultFormat == formatTabular {
+	case formatTabular:
+		nullPrinter := nullprinter.NewNullPrinter(untypedSch)
+		p.AddStage(pipeline.NewNamedTransform(nullprinter.NullPrintingStage, nullPrinter.ProcessRow))
 		autoSizeTransform := fwt.NewAutoSizingFWTTransformer(untypedSch, fwt.PrintAllWhenTooLong, 10000)
 		p.AddStage(pipeline.NamedTransform{Name: fwtStageName, Func: autoSizeTransform.TransformToFWT})
 	}
@@ -1198,6 +1207,8 @@ func (se *sqlEngine) prettyPrintResults(ctx context.Context, sqlSch sql.Schema,
 		wr, err = tabular.NewTextTableWriter(cliWr, untypedSch)
 	case formatCsv:
 		wr, err = csv.NewCSVWriter(cliWr, untypedSch, csv.NewCSVInfo())
+	case formatJson:
+		wr, err = json.NewJSONWriter(cliWr, untypedSch)
 	default:
 		panic("unimplemented output format type")
 	}

go/libraries/doltcore/diff/sql_diff.go

@@ -188,7 +188,7 @@ func PrintSqlTableDiffs(ctx context.Context, r1, r2 *doltdb.RootValue, wr io.Wri
 				transforms := pipeline.NewTransformCollection()
 				nullPrinter := nullprinter.NewNullPrinter(sch)
 				transforms.AppendTransforms(
-					pipeline.NewNamedTransform(nullprinter.NULL_PRINTING_STAGE, nullPrinter.ProcessRow),
+					pipeline.NewNamedTransform(nullprinter.NullPrintingStage, nullPrinter.ProcessRow),
 				)
 				sink, err := NewSQLDiffSink(wr, sch, tblName)
 				if err != nil {

go/libraries/doltcore/table/untyped/nullprinter/nullprinter.go

@@ -21,18 +21,25 @@ import (
 	"github.com/liquidata-inc/dolt/go/store/types"
 )
 
-const PRINTED_NULL = "<NULL>"
+const PrintedNull = "<NULL>"
 
-const NULL_PRINTING_STAGE = "null printing"
+const NullPrintingStage = "null printing"
 
 // NullPrinter is a utility to convert nil values in rows to a string representation.
 type NullPrinter struct {
 	Sch schema.Schema
+	nullStr string
 }
 
 // NewNullPrinter returns a new null printer for the schema given, which must be string-typed (untyped).
 func NewNullPrinter(sch schema.Schema) *NullPrinter {
-	return &NullPrinter{Sch: sch}
+	return &NullPrinter{Sch: sch, nullStr: PrintedNull}
+}
+
+// NewNullPrinterWithNullString returns a new null printer for the schema given, which must be string-typed, using the
+// string given as the value to print for nulls.
+func NewNullPrinterWithNullString(sch schema.Schema, nullStr string) *NullPrinter {
+	return &NullPrinter{Sch: sch, nullStr: nullStr}
 }
 
 // Function to convert any nil values for a row with the schema given to a string representation. Used as the transform
@@ -44,7 +51,7 @@ func (np *NullPrinter) ProcessRow(inRow row.Row, props pipeline.ReadableMap) (ro
 		if !types.IsNull(val) {
 			taggedVals[tag] = val
 		} else {
-			taggedVals[tag] = types.String(PRINTED_NULL)
+			taggedVals[tag] = types.String(np.nullStr)
 		}
 
 		return false, nil