Add support for SELECT_JSON statements.

postgres/select_json.go

@@ -0,0 +1,131 @@
+package postgres
+
+import (
+	"github.com/go-jet/jet/v2/internal/jet"
+	"strings"
+)
+
+// SELECT_JSON_ARR creates a new SelectJsonStatement with a list of projections.
+func SELECT_JSON_ARR(projections ...Projection) SelectStatement {
+	return newSelectStatementJson(projections, jet.SelectJsonArrStatementType)
+}
+
+// SELECT_JSON_OBJ creates a new SelectJsonStatement with a list of projections.
+func SELECT_JSON_OBJ(projections ...Projection) SelectStatement {
+	return newSelectStatementJson(projections, jet.SelectJsonObjStatementType)
+}
+
+type selectJsonStatement struct {
+	*selectStatementImpl
+
+	subQuery      *selectStatementImpl
+	statementType jet.StatementType
+}
+
+func (s *selectJsonStatement) AS(alias string) Projection {
+	s.setSubQueryAlias(strings.ToLower(alias) + "_")
+
+	return s.selectStatementImpl.AS(alias)
+}
+
+func (s *selectJsonStatement) FROM(table ...ReadableTable) SelectStatement {
+	s.subQuery.From.Tables = readableTablesToSerializerList(table)
+
+	return s
+}
+
+func (s *selectJsonStatement) DISTINCT(on ...jet.ColumnExpression) SelectStatement {
+	s.subQuery.Select.Distinct = true
+	s.subQuery.Select.DistinctOnColumns = on
+	return s
+}
+
+func (s *selectJsonStatement) WHERE(condition BoolExpression) SelectStatement {
+	s.subQuery.Where.Condition = condition
+	return s
+}
+
+func (s *selectJsonStatement) GROUP_BY(groupByClauses ...GroupByClause) SelectStatement {
+	s.subQuery.GroupBy.List = groupByClauses
+	return s
+}
+
+func (s *selectJsonStatement) HAVING(boolExpression BoolExpression) SelectStatement {
+	s.subQuery.Having.Condition = boolExpression
+	return s
+}
+
+func (s *selectJsonStatement) WINDOW(name string) windowExpand {
+	s.subQuery.Window.Definitions = append(s.subQuery.Window.Definitions, jet.WindowDefinition{Name: name})
+	return windowExpand{
+		selectStatement: s.subQuery,
+		rootStmt:        s,
+	}
+}
+
+func (s *selectJsonStatement) ORDER_BY(orderByClauses ...OrderByClause) SelectStatement {
+	s.subQuery.OrderBy.List = orderByClauses
+	return s
+}
+
+func (s *selectJsonStatement) LIMIT(limit int64) SelectStatement {
+	s.subQuery.Limit.Count = limit
+	return s
+}
+
+func (s *selectJsonStatement) OFFSET(offset int64) SelectStatement {
+	s.subQuery.Offset.Count = Int(offset)
+	return s
+}
+
+func (s *selectJsonStatement) OFFSET_e(offset IntegerExpression) SelectStatement {
+	s.subQuery.Offset.Count = offset
+	return s
+}
+
+func (s *selectJsonStatement) FETCH_FIRST(count IntegerExpression) fetchExpand {
+	s.subQuery.Fetch.Count = count
+
+	return fetchExpand{
+		selectStatement: s.subQuery,
+		rootStmt:        s,
+	}
+}
+
+func (s *selectJsonStatement) FOR(lock RowLock) SelectStatement {
+	s.subQuery.For.Lock = lock
+	return s
+}
+
+func newSelectStatementJson(projections []Projection, statementType jet.StatementType) SelectStatement {
+	newSelectJson := &selectJsonStatement{
+		selectStatementImpl: newSelectStatement(statementType, nil, nil),
+		subQuery:            newSelectStatement(statementType, nil, projections),
+		statementType:       statementType,
+	}
+
+	newSelectJson.setOperatorsImpl.stmtRoot = newSelectJson
+
+	newSelectJson.setSubQueryAlias("")
+
+	return newSelectJson
+}
+
+func (s *selectJsonStatement) setSubQueryAlias(alias string) {
+	subQueryAlias := alias + "records"
+	jsonAlias := alias + "json"
+
+	s.Select.ProjectionList = ProjectionList{constructJsonFunc(s.statementType, subQueryAlias).AS(jsonAlias)}
+
+	s.From.Tables = []jet.Serializer{newSelectTable(s.subQuery, subQueryAlias, nil)}
+}
+
+func constructJsonFunc(statementType jet.StatementType, subQueryAlias string) Expression {
+	rowToJson := Func("row_to_json", CustomExpression(Token(subQueryAlias)))
+
+	if statementType == jet.SelectJsonArrStatementType {
+		return Func("json_agg", rowToJson)
+	}
+
+	return rowToJson
+}