Added support for 'SELECT VALUE' statement

api/handlers/middleware/loggers.go

@@ -14,7 +14,10 @@ func RequestLogger() gin.HandlerFunc {
 		rdr1 := io.NopCloser(bytes.NewBuffer(buf))
 		rdr2 := io.NopCloser(bytes.NewBuffer(buf))
 
-		fmt.Println(readBody(rdr1))
+		bodyStr := readBody(rdr1)
+		if bodyStr != "" {
+			fmt.Println(bodyStr)
+		}
 
 		c.Request.Body = rdr2
 		c.Next()

parsers/models.go

@@ -16,19 +16,30 @@ const (
 	ConstantTypeBoolean
 )
 
+type SelectItemType int
+
+const (
+	SelectItemTypeField SelectItemType = iota
+	SelectItemTypeObject
+	SelectItemTypeArray
+)
+
 type SelectStmt struct {
-	Columns []FieldPath
+	SelectItems []SelectItem
-	Table   Table
+	Table       Table
-	Filters interface{}
+	Filters     interface{}
 }
 
 type Table struct {
 	Value string
 }
 
-type FieldPath struct {
+type SelectItem struct {
-	Alias string
+	Alias       string
-	Path  []string
+	Path        []string
+	SelectItems []SelectItem
+	Type        SelectItemType
+	IsTopLevel  bool
 }
 
 type LogicalExpression struct {

parsers/nosql/nosql.peg

@@ -5,7 +5,7 @@ import "github.com/pikami/cosmium/parsers"
 
 func makeSelectStmt(columns, table, whereClause interface{}) (parsers.SelectStmt, error) {
     selectStmt := parsers.SelectStmt{
-		Columns: columns.([]parsers.FieldPath),
+		SelectItems: columns.([]parsers.SelectItem),
 		Table:   table.(parsers.Table),
 	}
 
@@ -18,7 +18,7 @@ func makeSelectStmt(columns, table, whereClause interface{}) (parsers.SelectStmt
 	return selectStmt, nil
 }
 
-func makeFieldPath(name interface{}, path interface{}, alias interface{}) (parsers.FieldPath, error) {
+func makeSelectItem(name interface{}, path interface{}, alias interface{}, selectItemType parsers.SelectItemType) (parsers.SelectItem, error) {
 	ps := path.([]interface{})
 
 	paths := make([]string, 1)
@@ -27,21 +27,21 @@ func makeFieldPath(name interface{}, path interface{}, alias interface{}) (parse
         paths = append(paths, p.(string))
 	}
 
-    fieldPath := parsers.FieldPath{Path: paths}
+    selectItem := parsers.SelectItem{Path: paths, Type: selectItemType}
     if aliasValue, ok := alias.(string); ok {
-        fieldPath.Alias = aliasValue
+        selectItem.Alias = aliasValue
     }
 
-	return fieldPath, nil
+	return selectItem, nil
 }
 
-func makeColumnList(column interface{}, other_columns interface{}) ([]parsers.FieldPath, error) {
+func makeColumnList(column interface{}, other_columns interface{}) ([]parsers.SelectItem, error) {
     collsAsArray := other_columns.([]interface{})
-	columnList := make([]parsers.FieldPath, len(collsAsArray) + 1)
+	columnList := make([]parsers.SelectItem, len(collsAsArray) + 1)
-	columnList[0] = column.(parsers.FieldPath)
+	columnList[0] = column.(parsers.SelectItem)
 
 	for i, v := range collsAsArray {
-        if col, ok := v.(parsers.FieldPath); ok {
+        if col, ok := v.(parsers.SelectItem); ok {
 			columnList[i+1] = col
         }
     }
@@ -79,23 +79,31 @@ Input <- selectStmt:SelectStmt {
     return selectStmt, nil
 }
 
-SelectStmt <- Select ws columns:ColumnList ws
+SelectStmt <- Select ws columns:Selection ws
     From ws table:TableName ws
     whereClause:(ws Where ws condition:Condition { return condition, nil })? {
     return makeSelectStmt(columns, table, whereClause)
 }
 
-ColumnList <- column:FieldPath other_columns:(ws "," ws coll:FieldPath {return coll, nil })* {
+Selection <- SelectValueSpec / ColumnList
+
+ColumnList <- column:SelectItem other_columns:(ws "," ws coll:SelectItem {return coll, nil })* {
     return makeColumnList(column, other_columns)
 }
 
+SelectValueSpec <- "VALUE" ws column:SelectItem {
+    selectItem := column.(parsers.SelectItem)
+	selectItem.IsTopLevel = true
+    return makeColumnList(selectItem, make([]interface{}, 0))
+}
+
 TableName <- key:Identifier {
     return parsers.Table{Value: key.(string)}, nil
 }
 
-FieldPath <- name:Identifier path:(DotFieldAccess / ArrayFieldAccess)*
+SelectItem <- name:Identifier path:(DotFieldAccess / ArrayFieldAccess)*
     asClause:(ws "AS" ws alias:Identifier { return alias, nil })? {
-    return makeFieldPath(name, path, asClause)
+    return makeSelectItem(name, path, asClause, parsers.SelectItemTypeField)
 }
 
 DotFieldAccess <- "." id:Identifier {
@@ -122,7 +130,7 @@ AndExpression <- ex1:ComparisonExpression ex2:(ws "AND" ws ex:ComparisonExpressi
     return combineExpressions(ex1, ex2, parsers.LogicalExpressionTypeAnd)
 }
 
-ComparisonExpression <- left:(Literal / FieldPath) ws op:ComparisonOperator ws right:(Literal / FieldPath) {
+ComparisonExpression <- left:(Literal / SelectItem) ws op:ComparisonOperator ws right:(Literal / SelectItem) {
     return parsers.ComparisonExpression{Left:left,Right:right,Operation:string(op.([]uint8))}, nil
 }
 

parsers/nosql/nosql_test.go

@@ -12,7 +12,7 @@ import (
 // For Parser Debugging
 // func Test_ParseTest(t *testing.T) {
 // 	// select c.id, c._self, c._rid, c._ts, [c[\"pk\"]] as _partitionKeyValue from c
-// 	res, err := nosql.Parse("", []byte("select c.id, c._self AS self, c._rid, c._ts FROM c where c.id=\"12345\" AND c.pk=123"))
+// 	res, err := nosql.Parse("", []byte("SELECT VALUE c.id FROM c"))
 // 	if err != nil {
 // 		log.Fatal(err)
 // 	}
@@ -38,12 +38,12 @@ func testQueryParse(t *testing.T, query string, expectedQuery parsers.SelectStmt
 }
 
 func Test_Parse(t *testing.T) {
-	t.Run("Shoul parse simple SELECT", func(t *testing.T) {
+	t.Run("Should parse simple SELECT", func(t *testing.T) {
 		testQueryParse(
 			t,
 			`SELECT c.id, c["pk"] FROM c`,
 			parsers.SelectStmt{
-				Columns: []parsers.FieldPath{
+				SelectItems: []parsers.SelectItem{
 					{Path: []string{"c", "id"}},
 					{Path: []string{"c", "pk"}},
 				},
@@ -52,6 +52,19 @@ func Test_Parse(t *testing.T) {
 		)
 	})
 
+	t.Run("Should parse SELECT VALUE", func(t *testing.T) {
+		testQueryParse(
+			t,
+			`SELECT VALUE c.id FROM c`,
+			parsers.SelectStmt{
+				SelectItems: []parsers.SelectItem{
+					{Path: []string{"c", "id"}, IsTopLevel: true},
+				},
+				Table: parsers.Table{Value: "c"},
+			},
+		)
+	})
+
 	t.Run("Should parse SELECT with single WHERE condition", func(t *testing.T) {
 		testQueryParse(
 			t,
@@ -59,13 +72,13 @@ func Test_Parse(t *testing.T) {
 			FROM c
 			WHERE c.isCool=true`,
 			parsers.SelectStmt{
-				Columns: []parsers.FieldPath{
+				SelectItems: []parsers.SelectItem{
 					{Path: []string{"c", "id"}},
 				},
 				Table: parsers.Table{Value: "c"},
 				Filters: parsers.ComparisonExpression{
 					Operation: "=",
-					Left:      parsers.FieldPath{Path: []string{"c", "isCool"}},
+					Left:      parsers.SelectItem{Path: []string{"c", "isCool"}},
 					Right:     parsers.Constant{Type: parsers.ConstantTypeBoolean, Value: true},
 				},
 			},
@@ -79,7 +92,7 @@ func Test_Parse(t *testing.T) {
 			FROM c
 			WHERE c.id="12345" OR c.pk=123`,
 			parsers.SelectStmt{
-				Columns: []parsers.FieldPath{
+				SelectItems: []parsers.SelectItem{
 					{Path: []string{"c", "id"}},
 					{Path: []string{"c", "_self"}, Alias: "self"},
 					{Path: []string{"c", "_rid"}},
@@ -91,12 +104,12 @@ func Test_Parse(t *testing.T) {
 					Expressions: []interface{}{
 						parsers.ComparisonExpression{
 							Operation: "=",
-							Left:      parsers.FieldPath{Path: []string{"c", "id"}},
+							Left:      parsers.SelectItem{Path: []string{"c", "id"}},
 							Right:     parsers.Constant{Type: parsers.ConstantTypeString, Value: "12345"},
 						},
 						parsers.ComparisonExpression{
 							Operation: "=",
-							Left:      parsers.FieldPath{Path: []string{"c", "pk"}},
+							Left:      parsers.SelectItem{Path: []string{"c", "pk"}},
 							Right:     parsers.Constant{Type: parsers.ConstantTypeInteger, Value: 123},
 						},
 					},
@@ -105,7 +118,7 @@ func Test_Parse(t *testing.T) {
 		)
 	})
 
-	t.Run("Shoul correctly parse literals in conditions", func(t *testing.T) {
+	t.Run("Should correctly parse literals in conditions", func(t *testing.T) {
 		testQueryParse(
 			t,
 			`select c.id
@@ -115,27 +128,27 @@ func Test_Parse(t *testing.T) {
 				AND c.float=6.9
 				AND c.string="hello"`,
 			parsers.SelectStmt{
-				Columns: []parsers.FieldPath{{Path: []string{"c", "id"}, Alias: ""}},
+				SelectItems: []parsers.SelectItem{{Path: []string{"c", "id"}, Alias: ""}},
-				Table:   parsers.Table{Value: "c"},
+				Table:       parsers.Table{Value: "c"},
 				Filters: parsers.LogicalExpression{
 					Expressions: []interface{}{
 						parsers.ComparisonExpression{
-							Left:      parsers.FieldPath{Path: []string{"c", "boolean"}},
+							Left:      parsers.SelectItem{Path: []string{"c", "boolean"}},
 							Right:     parsers.Constant{Type: 3, Value: true},
 							Operation: "=",
 						},
 						parsers.ComparisonExpression{
-							Left:      parsers.FieldPath{Path: []string{"c", "integer"}},
+							Left:      parsers.SelectItem{Path: []string{"c", "integer"}},
 							Right:     parsers.Constant{Type: 1, Value: 1},
 							Operation: "=",
 						},
 						parsers.ComparisonExpression{
-							Left:      parsers.FieldPath{Path: []string{"c", "float"}},
+							Left:      parsers.SelectItem{Path: []string{"c", "float"}},
 							Right:     parsers.Constant{Type: 2, Value: 6.9},
 							Operation: "=",
 						},
 						parsers.ComparisonExpression{
-							Left:      parsers.FieldPath{Path: []string{"c", "string"}},
+							Left:      parsers.SelectItem{Path: []string{"c", "string"}},
 							Right:     parsers.Constant{Type: 0, Value: "hello"},
 							Operation: "=",
 						},

query_executors/memory_executor/memory_executor.go

@@ -14,24 +14,33 @@ func Execute(query parsers.SelectStmt, data []RowType) []RowType {
 	for _, row := range data {
 		// Check if the row satisfies the filter conditions
 		if evaluateFilters(query.Filters, row) {
-			// Construct a new row based on the selected columns
+			result = append(result, selectRow(query.SelectItems, row))
-			newRow := make(map[string]interface{})
-			for _, column := range query.Columns {
-				destinationName := column.Alias
-				if destinationName == "" {
-					destinationName = column.Path[len(column.Path)-1]
-				}
-
-				newRow[destinationName] = getFieldValue(column, row)
-			}
-			// Add the new row to the result
-			result = append(result, newRow)
 		}
 	}
 
 	return result
 }
 
+func selectRow(selectItems []parsers.SelectItem, row RowType) interface{} {
+	// When the first value is top level, select it instead
+	if len(selectItems) > 0 && selectItems[0].IsTopLevel {
+		return getFieldValue(selectItems[0], row)
+	}
+
+	// Construct a new row based on the selected columns
+	newRow := make(map[string]interface{})
+	for _, column := range selectItems {
+		destinationName := column.Alias
+		if destinationName == "" {
+			destinationName = column.Path[len(column.Path)-1]
+		}
+
+		newRow[destinationName] = getFieldValue(column, row)
+	}
+
+	return newRow
+}
+
 // Helper function to evaluate filter conditions recursively
 func evaluateFilters(expr ExpressionType, row RowType) bool {
 	if expr == nil {
@@ -74,7 +83,7 @@ func evaluateFilters(expr ExpressionType, row RowType) bool {
 	return false
 }
 
-func getFieldValue(field parsers.FieldPath, row RowType) interface{} {
+func getFieldValue(field parsers.SelectItem, row RowType) interface{} {
 	value := row
 	for _, pathSegment := range field.Path[1:] {
 		if nestedValue, ok := value.(map[string]interface{}); ok {
@@ -88,7 +97,7 @@ func getFieldValue(field parsers.FieldPath, row RowType) interface{} {
 
 func getExpressionParameterValue(parameter interface{}, row RowType) interface{} {
 	switch typedParameter := parameter.(type) {
-	case parsers.FieldPath:
+	case parsers.SelectItem:
 		return getFieldValue(typedParameter, row)
 	case parsers.Constant:
 		return typedParameter.Value

query_executors/memory_executor/memory_executor_test.go

@@ -27,11 +27,11 @@ func Test_Execute(t *testing.T) {
 		map[string]interface{}{"id": "67890", "pk": 456, "_self": "self2", "_rid": "rid2", "_ts": 789012, "isCool": true},
 	}
 
-	t.Run("Shoul execute simple SELECT", func(t *testing.T) {
+	t.Run("Should execute simple SELECT", func(t *testing.T) {
 		testQueryExecute(
 			t,
 			parsers.SelectStmt{
-				Columns: []parsers.FieldPath{
+				SelectItems: []parsers.SelectItem{
 					{Path: []string{"c", "id"}},
 					{Path: []string{"c", "pk"}},
 				},
@@ -45,17 +45,34 @@ func Test_Execute(t *testing.T) {
 		)
 	})
 
-	t.Run("Shoul execute SELECT with single WHERE condition", func(t *testing.T) {
+	t.Run("Should execute SELECT VALUE", func(t *testing.T) {
 		testQueryExecute(
 			t,
 			parsers.SelectStmt{
-				Columns: []parsers.FieldPath{
+				SelectItems: []parsers.SelectItem{
+					{Path: []string{"c", "id"}, IsTopLevel: true},
+				},
+				Table: parsers.Table{Value: "c"},
+			},
+			mockData,
+			[]memoryexecutor.RowType{
+				"12345",
+				"67890",
+			},
+		)
+	})
+
+	t.Run("Should execute SELECT with single WHERE condition", func(t *testing.T) {
+		testQueryExecute(
+			t,
+			parsers.SelectStmt{
+				SelectItems: []parsers.SelectItem{
 					{Path: []string{"c", "id"}},
 				},
 				Table: parsers.Table{Value: "c"},
 				Filters: parsers.ComparisonExpression{
 					Operation: "=",
-					Left:      parsers.FieldPath{Path: []string{"c", "isCool"}},
+					Left:      parsers.SelectItem{Path: []string{"c", "isCool"}},
 					Right:     parsers.Constant{Type: parsers.ConstantTypeBoolean, Value: true},
 				},
 			},
@@ -70,7 +87,7 @@ func Test_Execute(t *testing.T) {
 		testQueryExecute(
 			t,
 			parsers.SelectStmt{
-				Columns: []parsers.FieldPath{
+				SelectItems: []parsers.SelectItem{
 					{Path: []string{"c", "id"}},
 					{Path: []string{"c", "_self"}, Alias: "self"},
 				},
@@ -80,12 +97,12 @@ func Test_Execute(t *testing.T) {
 					Expressions: []interface{}{
 						parsers.ComparisonExpression{
 							Operation: "=",
-							Left:      parsers.FieldPath{Path: []string{"c", "id"}},
+							Left:      parsers.SelectItem{Path: []string{"c", "id"}},
 							Right:     parsers.Constant{Type: parsers.ConstantTypeString, Value: "67890"},
 						},
 						parsers.ComparisonExpression{
 							Operation: "=",
-							Left:      parsers.FieldPath{Path: []string{"c", "pk"}},
+							Left:      parsers.SelectItem{Path: []string{"c", "pk"}},
 							Right:     parsers.Constant{Type: parsers.ConstantTypeInteger, Value: 456},
 						},
 					},