Add support for SELECT_JSON statements.

mysql/functions.go

@@ -148,6 +148,11 @@ var NTH_VALUE = jet.NTH_VALUE
 
 //--------------------- String functions ------------------//
 
+// HEX function in MySQL takes an input and returns its equivalent hexadecimal representation
+func HEX(expression Expression) StringExpression {
+	return StringExp(Func("HEX", expression))
+}
+
 // BIT_LENGTH returns number of bits in string expression
 var BIT_LENGTH = jet.BIT_LENGTH
 

mysql/select_json.go

@@ -0,0 +1,79 @@
+package mysql
+
+import (
+	"github.com/go-jet/jet/v2/internal/jet"
+)
+
+// SelectJsonStatement is an interface for MySQL statements that generate JSON on the server.
+type SelectJsonStatement interface {
+	Statement
+	jet.Serializer
+
+	AS(alias string) Projection
+
+	FROM(table ReadableTable) SelectJsonStatement
+	WHERE(condition BoolExpression) SelectJsonStatement
+	ORDER_BY(orderByClauses ...OrderByClause) SelectJsonStatement
+	LIMIT(limit int64) SelectJsonStatement
+	OFFSET(offset int64) SelectJsonStatement
+}
+
+// SELECT_JSON_ARR creates a new SelectJsonStatement with a list of projections.
+func SELECT_JSON_ARR(projections ...Projection) SelectJsonStatement {
+	return newSelectStatementJson(projections, jet.SelectJsonArrStatementType)
+}
+
+// SELECT_JSON_OBJ creates a new SelectJsonStatement with a list of projections.
+func SELECT_JSON_OBJ(projections ...Projection) SelectJsonStatement {
+	return newSelectStatementJson(projections, jet.SelectJsonObjStatementType)
+}
+
+type selectJsonStatement struct {
+	*selectStatementImpl
+}
+
+func newSelectStatementJson(projections []Projection, statementType jet.StatementType) SelectJsonStatement {
+	newSelect := &selectJsonStatement{
+		selectStatementImpl: newSelectStatement(statementType, nil, nil),
+	}
+
+	newSelect.Select.ProjectionList = ProjectionList{constructJsonFunc(projections, statementType).AS("json")}
+
+	return newSelect
+}
+
+func constructJsonFunc(projections []Projection, statementType jet.StatementType) Expression {
+	jsonObj := Func("JSON_OBJECT", CustomExpression(jet.JsonProjectionList(projections)))
+
+	if statementType == jet.SelectJsonArrStatementType {
+		return Func("JSON_ARRAYAGG", jsonObj)
+	}
+
+	return jsonObj
+}
+
+func (s *selectJsonStatement) FROM(table ReadableTable) SelectJsonStatement {
+	s.From.Tables = []jet.Serializer{table}
+
+	return s
+}
+
+func (s *selectJsonStatement) WHERE(condition BoolExpression) SelectJsonStatement {
+	s.Where.Condition = condition
+	return s
+}
+
+func (s *selectJsonStatement) ORDER_BY(orderByClauses ...OrderByClause) SelectJsonStatement {
+	s.OrderBy.List = orderByClauses
+	return s
+}
+
+func (s *selectJsonStatement) LIMIT(limit int64) SelectJsonStatement {
+	s.Limit.Count = limit
+	return s
+}
+
+func (s *selectJsonStatement) OFFSET(offset int64) SelectJsonStatement {
+	s.Offset.Count = Int(offset)
+	return s
+}

mysql/select_statement.go

@@ -62,12 +62,12 @@ type SelectStatement interface {
 
 // SELECT creates new SelectStatement with list of projections
 func SELECT(projection Projection, projections ...Projection) SelectStatement {
-	return newSelectStatement(nil, append([]Projection{projection}, projections...))
+	return newSelectStatement(jet.SelectStatementType, nil, append([]Projection{projection}, projections...))
 }
 
-func newSelectStatement(table ReadableTable, projections []Projection) SelectStatement {
+func newSelectStatement(stmtType jet.StatementType, table ReadableTable, projections []Projection) *selectStatementImpl {
 	newSelect := &selectStatementImpl{}
-	newSelect.ExpressionStatement = jet.NewExpressionStatementImpl(Dialect, jet.SelectStatementType, newSelect,
+	newSelect.ExpressionStatement = jet.NewExpressionStatementImpl(Dialect, stmtType, newSelect,
 		&newSelect.Select,
 		&newSelect.From,
 		&newSelect.Where,

mysql/table.go

@@ -50,7 +50,7 @@ type readableTableInterfaceImpl struct {
 
 // Generates a select query on the current tableName.
 func (r readableTableInterfaceImpl) SELECT(projection1 Projection, projections ...Projection) SelectStatement {
-	return newSelectStatement(r.parent, append([]Projection{projection1}, projections...))
+	return newSelectStatement(jet.SelectStatementType, r.parent, append([]Projection{projection1}, projections...))
 }
 
 // Creates a inner join tableName Expression using onCondition.