feat: add StrictFieldMapping config

qrm/qrm.go

@@ -6,8 +6,9 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
-	"github.com/go-jet/jet/v2/internal/utils/must"
 	"reflect"
+
+	"github.com/go-jet/jet/v2/internal/utils/must"
 )
 
 // Config holds the configuration settings for QRM scanning behavior.
@@ -18,6 +19,13 @@ type Config struct {
 	// Does not apply to statements build with SELECT_JSON_OBJ or SELECT_JSON_ARR
 	StrictScan bool
 
+	// StrictFieldMapping, when true, causes the scanning function to panic if it encounters any
+	// destination struct fields that do not have matching columns in the SQL query result.
+	// This check applies only to fields that are mapped from a single column (simple/scanner/json_column).
+	// Complex fields (struct/slice) are excluded because they are populated recursively and can be optional.
+	// Does not apply to statements build with SELECT_JSON_OBJ or SELECT_JSON_ARR
+	StrictFieldMapping bool
+
 	// JsonUnmarshalFunc is called by the Query method to unmarshal JSON query results created by
 	// SELECT_JSON_OBJ and SELECT_JSON_ARR statements.
 	// It can be replaced with any implementation that matches the standard "encoding/json" `Unmarshal` function signature.
@@ -28,8 +36,9 @@ type Config struct {
 // GlobalConfig is the package-wide configuration for SQL scanning.
 // This variable is not thread safe, and it should be modified only once, for instance, during application initialization.
 var GlobalConfig = Config{
-	StrictScan:        false,
+	StrictScan:         false,
-	JsonUnmarshalFunc: json.Unmarshal,
+	StrictFieldMapping: false,
+	JsonUnmarshalFunc:  json.Unmarshal,
 }
 
 // ErrNoRows is returned by Query when query result set is empty
@@ -230,6 +239,9 @@ func ScanOneRowToDest(scanContext *ScanContext, rows *sql.Rows, destPtr interfac
 	}
 
 	scanContext.EnsureEveryColumnRead() // can panic
+	if GlobalConfig.StrictFieldMapping {
+		scanContext.EnsureEveryFieldMapped() // can panic
+	}
 
 	return nil
 }
@@ -276,6 +288,9 @@ func queryToSlice(ctx context.Context, db Queryable, query string, args []interf
 		if scanContext.rowNum == 1 && GlobalConfig.StrictScan {
 			scanContext.EnsureEveryColumnRead()
 		}
+		if scanContext.rowNum == 1 && GlobalConfig.StrictFieldMapping {
+			scanContext.EnsureEveryFieldMapped()
+		}
 	}
 
 	err = rows.Close()

qrm/scan_context.go

@@ -20,6 +20,8 @@ type ScanContext struct {
 	typesVisited    typeStack // to prevent circular dependency scan
 	columnAlias     []string
 	columnIndexRead []bool
+
+	unmappedFields []string
 }
 
 // NewScanContext creates new ScanContext from rows
@@ -79,6 +81,33 @@ func (s *ScanContext) EnsureEveryColumnRead() {
 	}
 }
 
+func (s *ScanContext) recordUnmappedField(structType reflect.Type, parentField *reflect.StructField, field reflect.StructField) {
+	// skip private/unsettable fields (those are ignored by mapRowToStruct anyway)
+	if field.PkgPath != "" {
+		return
+	}
+
+	// NOTE: For unnamed/anonymous structs, Name() is empty, so String() is used for readability/uniqueness.
+	typeName := structType.String()
+	if structType.Name() != "" {
+		typeName = structType.Name()
+	}
+
+	fieldIdent := fmt.Sprintf("%s.%s", typeName, field.Name)
+	if parentField != nil {
+		fieldIdent = fmt.Sprintf("%s.%s.%s", typeName, parentField.Name, field.Name)
+	}
+
+	s.unmappedFields = append(s.unmappedFields, fmt.Sprintf("'%s'", fieldIdent))
+}
+
+func (s *ScanContext) EnsureEveryFieldMapped() {
+	if len(s.unmappedFields) == 0 {
+		return
+	}
+	panic("jet: fields never mapped: " + strings.Join(s.unmappedFields, ", "))
+}
+
 func createScanSlice(columnCount int) []interface{} {
 	scanPtrSlice := make([]interface{}, columnCount)
 
@@ -144,6 +173,10 @@ func (s *ScanContext) getTypeInfo(structType reflect.Type, parentField *reflect.
 			fieldMap.Type = simpleType
 		}
 
+		if GlobalConfig.StrictFieldMapping && fieldMap.rowIndex == -1 && fieldMap.Type != complexType {
+			s.recordUnmappedField(structType, parentField, field)
+		}
+
 		newTypeInfo.fieldMappings = append(newTypeInfo.fieldMappings, fieldMap)
 	}
 

tests/sqlite/main_test.go

@@ -4,15 +4,17 @@ import (
 	"context"
 	"database/sql"
 	"fmt"
+	"os"
+	"runtime"
+	"testing"
+
 	"github.com/go-jet/jet/v2/internal/utils/throw"
+	"github.com/go-jet/jet/v2/qrm"
 	"github.com/go-jet/jet/v2/sqlite"
 	"github.com/go-jet/jet/v2/stmtcache"
 	"github.com/go-jet/jet/v2/tests/dbconfig"
 	"github.com/pkg/profile"
 	"github.com/stretchr/testify/require"
-	"os"
-	"runtime"
-	"testing"
 
 	_ "github.com/mattn/go-sqlite3"
 )
@@ -57,6 +59,20 @@ func TestMain(m *testing.M) {
 
 }
 
+func allowUnmappedFields(f func()) {
+	previous := qrm.GlobalConfig.StrictFieldMapping
+	defer func() { qrm.GlobalConfig.StrictFieldMapping = previous }()
+	qrm.GlobalConfig.StrictFieldMapping = false
+	f()
+}
+
+func requireStrictFieldMapping(f func()) {
+	previous := qrm.GlobalConfig.StrictFieldMapping
+	defer func() { qrm.GlobalConfig.StrictFieldMapping = previous }()
+	qrm.GlobalConfig.StrictFieldMapping = true
+	f()
+}
+
 func runCount(stmtCaching bool) int {
 	if stmtCaching {
 		return 4

tests/sqlite/select_test.go

@@ -2,13 +2,14 @@ package sqlite
 
 import (
 	"context"
-	"github.com/go-jet/jet/v2/internal/utils/ptr"
-	model2 "github.com/go-jet/jet/v2/tests/.gentestdata/sqlite/chinook/model"
-	"github.com/go-jet/jet/v2/tests/.gentestdata/sqlite/chinook/table"
 	"strings"
 	"testing"
 	"time"
 
+	"github.com/go-jet/jet/v2/internal/utils/ptr"
+	model2 "github.com/go-jet/jet/v2/tests/.gentestdata/sqlite/chinook/model"
+	"github.com/go-jet/jet/v2/tests/.gentestdata/sqlite/chinook/table"
+
 	"github.com/go-jet/jet/v2/internal/testutils"
 	. "github.com/go-jet/jet/v2/sqlite"
 	"github.com/go-jet/jet/v2/tests/.gentestdata/sqlite/sakila/model"
@@ -43,6 +44,151 @@ WHERE actor.actor_id = ?;
 	requireQueryLogged(t, query, 1)
 }
 
+func TestStrictFieldMapping(t *testing.T) {
+	queryAll := SELECT(
+		Actor.AllColumns,
+	).FROM(
+		Actor,
+	).WHERE(
+		Actor.ActorID.EQ(Int(2)),
+	).LIMIT(1)
+
+	testutils.AssertStatementSql(t, queryAll, `
+SELECT actor.actor_id AS "actor.actor_id",
+     actor.first_name AS "actor.first_name",
+     actor.last_name AS "actor.last_name",
+     actor.last_update AS "actor.last_update"
+FROM actor
+WHERE actor.actor_id = ?
+LIMIT ?;
+`, int64(2), int64(1))
+
+	queryPartial := SELECT(
+		Actor.ActorID,
+		Actor.FirstName,
+	).FROM(
+		Actor,
+	).WHERE(
+		Actor.ActorID.EQ(Int(2)),
+	).LIMIT(1)
+
+	testutils.AssertStatementSql(t, queryPartial, `
+SELECT actor.actor_id AS "actor.actor_id",
+     actor.first_name AS "actor.first_name"
+FROM actor
+WHERE actor.actor_id = ?
+LIMIT ?;
+`, int64(2), int64(1))
+
+	// Destination model mapped via explicit field aliases ("actor.*").
+	type AliasedActor struct {
+		ActorID    int32  `alias:"actor.actor_id"`
+		FirstName  string `alias:"actor.first_name"`
+		LastName   string `alias:"actor.last_name"`
+		LastUpdate string `alias:"actor.last_update"`
+	}
+
+	t.Run("all columns scan succeeds for generated model", func(t *testing.T) {
+		allowUnmappedFields(func() {
+			var dest model.Actor
+			require.NoError(t, queryAll.Query(db, &dest))
+		})
+		requireStrictFieldMapping(func() {
+			var dest model.Actor
+			require.NoError(t, queryAll.Query(db, &dest))
+		})
+	})
+
+	t.Run("all columns scan succeeds for aliased destination", func(t *testing.T) {
+		allowUnmappedFields(func() {
+			var dest []AliasedActor
+			require.NoError(t, queryAll.Query(db, &dest))
+			require.Len(t, dest, 1)
+		})
+		requireStrictFieldMapping(func() {
+			var dest []AliasedActor
+			require.NoError(t, queryAll.Query(db, &dest))
+			require.Len(t, dest, 1)
+		})
+	})
+
+	t.Run("partial columns panics in strict mode for generated model", func(t *testing.T) {
+		allowUnmappedFields(func() {
+			var dest []model.Actor
+			require.NoError(t, queryPartial.Query(db, &dest))
+			require.Len(t, dest, 1)
+		})
+		requireStrictFieldMapping(func() {
+			require.PanicsWithValue(t, "jet: fields never mapped: 'Actor.LastName', 'Actor.LastUpdate'", func() {
+				var dest []model.Actor
+				_ = queryPartial.Query(db, &dest)
+			})
+		})
+	})
+
+	t.Run("partial columns panics in strict mode for aliased destination", func(t *testing.T) {
+		allowUnmappedFields(func() {
+			var dest []AliasedActor
+			require.NoError(t, queryPartial.Query(db, &dest))
+			require.Len(t, dest, 1)
+		})
+		requireStrictFieldMapping(func() {
+			require.PanicsWithValue(t, "jet: fields never mapped: 'AliasedActor.LastName', 'AliasedActor.LastUpdate'", func() {
+				var dest []AliasedActor
+				_ = queryPartial.Query(db, &dest)
+			})
+		})
+	})
+
+	t.Run("unexported fields are ignored by strict field mapping", func(t *testing.T) {
+		type Dest struct {
+			actorID int32 `alias:"actor.missing_column"`
+		}
+
+		requireStrictFieldMapping(func() {
+			var dest []Dest
+			require.NoError(t, queryAll.Query(db, &dest))
+		})
+	})
+
+	t.Run("nested unmapped field uses parent field name in error", func(t *testing.T) {
+		type Inner struct {
+			Missing string `alias:"actor.missing_column"`
+		}
+		type Outer struct {
+			Child Inner
+		}
+
+		requireStrictFieldMapping(func() {
+			require.PanicsWithValue(t, "jet: fields never mapped: 'Inner.Child.Missing'", func() {
+				var dest []Outer
+				_ = queryAll.Query(db, &dest)
+			})
+		})
+	})
+
+	t.Run("Rows.Scan triggers strict field mapping check", func(t *testing.T) {
+		type ActorLiteMissing struct {
+			ActorID   int32  `alias:"actor.actor_id"`
+			FirstName string `alias:"actor.first_name"`
+			LastName  string `alias:"actor.last_name"`
+		}
+
+		requireStrictFieldMapping(func() {
+			rows, err := queryPartial.Rows(context.Background(), db)
+			require.NoError(t, err)
+			require.True(t, rows.Next())
+
+			require.PanicsWithValue(t, "jet: fields never mapped: 'ActorLiteMissing.LastName'", func() {
+				var dest ActorLiteMissing
+				_ = rows.Scan(&dest)
+			})
+
+			_ = rows.Close()
+		})
+	})
+}
+
 var actor2 = model.Actor{
 	ActorID:    2,
 	FirstName:  "NICK",