🐛 修复创建数据冲突时的 MERGE 语法

Signed-off-by: liutianqi <[email protected]>

create.go

@@ -1,9 +1,6 @@
 package oracle
 
 import (
-	"bytes"
-
-	"github.com/godoes/gorm-oracle/clauses"
 	"gorm.io/gorm"
 	"gorm.io/gorm/callbacks"
 	"gorm.io/gorm/clause"
@@ -54,45 +51,7 @@ func Create(db *gorm.DB) {
 			}
 		}
 		if hasConflict {
-			stmt.AddClauseIfNotExists(clauses.Merge{
-				Using: []clause.Interface{
-					clause.Select{
-						Columns: func() (columns []clause.Column) {
-							// HACK: I can not come up with a better alternative for now
-							// I want to add a value to the list of variable and then capture the bind variable position as well
-							columns = values.Columns
-							for i, column := range columns {
-								buf := bytes.NewBufferString("")
-								stmt.Vars = append(stmt.Vars, values.Values[0][i])
-								stmt.BindVarTo(buf, stmt, nil)
-
-								column.Alias = column.Name
-								// then the captured bind var will be the name
-								column.Name = buf.String()
-								columns[i] = column
-							}
-							return
-						}(),
-					},
-					clause.From{
-						Tables: []clause.Table{{Name: db.Dialector.(*Dialector).DummyTableName()}},
-					},
-				},
-				On: func() (onExpr []clause.Expression) {
-					onExpr = make([]clause.Expression, len(stmtSchema.PrimaryFields))
-					for i, field := range stmtSchema.PrimaryFields {
-						onExpr[i] = clause.Eq{
-							Column: clause.Column{Table: stmt.Schema.Table, Name: field.DBName},
-							Value:  clause.Column{Table: clauses.MergeDefaultExcludeName(), Name: field.DBName},
-						}
-					}
-					return
-				}(),
-			})
-			stmt.AddClauseIfNotExists(clauses.WhenMatched{Set: onConflict.DoUpdates})
-			stmt.AddClauseIfNotExists(clauses.WhenNotMatched{Values: values})
-
-			stmt.Build("MERGE", "WHEN MATCHED", "WHEN NOT MATCHED")
+			MergeCreate(db, onConflict, values)
 		} else {
 			stmt.AddClauseIfNotExists(clause.Insert{Table: clause.Table{Name: stmt.Schema.Table}})
 			stmt.AddClause(clause.Values{Columns: values.Columns, Values: [][]interface{}{values.Values[0]}})
@@ -133,3 +92,85 @@ func Create(db *gorm.DB) {
 		}
 	}
 }
+
+func MergeCreate(db *gorm.DB, onConflict clause.OnConflict, values clause.Values) {
+	var dummyTable string
+	switch d := ptrDereference(db.Dialector).(type) {
+	case Dialector:
+		dummyTable = d.DummyTableName()
+	default:
+		dummyTable = "DUAL"
+	}
+
+	_, _ = db.Statement.WriteString("MERGE INTO ")
+	db.Statement.WriteQuoted(db.Statement.Table)
+	_, _ = db.Statement.WriteString(" USING (")
+
+	for idx, value := range values.Values {
+		if idx > 0 {
+			_, _ = db.Statement.WriteString(" UNION ALL ")
+		}
+
+		_, _ = db.Statement.WriteString("SELECT ")
+		for i, v := range value {
+			if i > 0 {
+				_ = db.Statement.WriteByte(',')
+			}
+			column := values.Columns[i]
+			db.Statement.AddVar(db.Statement, v)
+			_, _ = db.Statement.WriteString(" AS ")
+			db.Statement.WriteQuoted(column.Name)
+		}
+		_, _ = db.Statement.WriteString(" FROM ")
+		_, _ = db.Statement.WriteString(dummyTable)
+	}
+
+	_, _ = db.Statement.WriteString(`) `)
+	db.Statement.WriteQuoted("excluded")
+	_, _ = db.Statement.WriteString(" ON (")
+
+	var where clause.Where
+	for _, field := range db.Statement.Schema.PrimaryFields {
+		where.Exprs = append(where.Exprs, clause.Eq{
+			Column: clause.Column{Table: db.Statement.Table, Name: field.DBName},
+			Value:  clause.Column{Table: "excluded", Name: field.DBName},
+		})
+	}
+	where.Build(db.Statement)
+	_ = db.Statement.WriteByte(')')
+
+	if len(onConflict.DoUpdates) > 0 {
+		_, _ = db.Statement.WriteString(" WHEN MATCHED THEN UPDATE SET ")
+		onConflict.DoUpdates.Build(db.Statement)
+	}
+
+	_, _ = db.Statement.WriteString(" WHEN NOT MATCHED THEN INSERT (")
+
+	written := false
+	for _, column := range values.Columns {
+		if db.Statement.Schema.PrioritizedPrimaryField == nil || !db.Statement.Schema.PrioritizedPrimaryField.AutoIncrement || db.Statement.Schema.PrioritizedPrimaryField.DBName != column.Name {
+			if written {
+				_ = db.Statement.WriteByte(',')
+			}
+			written = true
+			db.Statement.WriteQuoted(column.Name)
+		}
+	}
+
+	_, _ = db.Statement.WriteString(") VALUES (")
+
+	written = false
+	for _, column := range values.Columns {
+		if db.Statement.Schema.PrioritizedPrimaryField == nil || !db.Statement.Schema.PrioritizedPrimaryField.AutoIncrement || db.Statement.Schema.PrioritizedPrimaryField.DBName != column.Name {
+			if written {
+				_ = db.Statement.WriteByte(',')
+			}
+			written = true
+			db.Statement.WriteQuoted(clause.Column{
+				Table: "excluded",
+				Name:  column.Name,
+			})
+		}
+	}
+	_, _ = db.Statement.WriteString(")")
+}

go.mod

@@ -9,6 +9,7 @@ require (
 )
 
 retract (
+	v1.5.12
 	v1.5.1
 	v1.5.0
 )