Merge pull request #53 from flycash/dev

expression: RawExpr accepts arguments

.CHANGELOG.md

@@ -17,7 +17,8 @@
 - [Force test and lint in pre-push](https://github.com/gotomicro/eql/pull/35)
 - [Insert implementation ](https://github.com/gotomicro/eql/pull/38)
 - [Delete implementation ](https://github.com/gotomicro/eql/pull/43)
-- [having implementation ](https://github.com/gotomicro/eql/pull/45)
+- [Having implementation ](https://github.com/gotomicro/eql/pull/45)
+- [RawExpr accepts arguments ](https://github.com/gotomicro/eql/pull/53)
 
 ### Docs, Lint issues and Examples
 - [Add examples and docs for Aggregate and Assign](https://github.com/gotomicro/eql/pull/50)

builder.go

@@ -73,7 +73,7 @@ func (b *builder) parameter(arg interface{}) {
 func (b *builder) buildExpr(expr Expr) error {
 	switch e := expr.(type) {
 	case RawExpr:
-		_, _ = b.buffer.WriteString(string(e))
+		b.buildRawExpr(e)
 	case Column:
 		cm, ok := b.meta.fieldMap[e.name]
 		if !ok {
@@ -121,6 +121,11 @@ func (b *builder) buildBinaryExpr(e binaryExpr) error {
 	return b.buildSubExpr(e.right)
 }
 
+func (b *builder) buildRawExpr(e RawExpr) {
+	_, _ = b.buffer.WriteString(e.raw)
+	b.args = append(b.args, e.args...)
+}
+
 func (b *builder) buildSubExpr(subExpr Expr) error {
 	switch r := subExpr.(type) {
 	case MathExpr:

db_test.go

@@ -60,10 +60,39 @@ func ExampleDB_Insert() {
 func ExampleDB_Select() {
 	db := New()
 	tm := &TestModel{}
-	query, _ := db.Select().From(tm).Build()
-	fmt.Printf("SQL: %s", query.SQL)
+	cases := []*Selector{
+		// case0: all columns are included
+		db.Select().From(tm),
+		// case1: only query specific columns
+		db.Select(Columns("Id", "Age")).From(tm),
+		// case2: using alias
+		db.Select(C("Id").As("my_id")).From(tm),
+		// case3: using aggregation function and alias
+		db.Select(Avg("Age").As("avg_age")).From(tm),
+		// case4: using raw expression
+		db.Select(Raw("COUNT(DISTINCT `age`) AS `age_cnt`")).From(tm),
+	}
+
+	for index, tc := range cases {
+		query, _ := tc.Build()
+		fmt.Printf("case%d:\n%s", index, query.string())
+	}
 	// Output:
+	// case0:
 	// SQL: SELECT `id`,`first_name`,`age`,`last_name` FROM `test_model`;
+	// Args: []interface {}(nil)
+	// case1:
+	// SQL: SELECT `id`,`age` FROM `test_model`;
+	// Args: []interface {}(nil)
+	// case2:
+	// SQL: SELECT `id` AS `my_id` FROM `test_model`;
+	// Args: []interface {}(nil)
+	// case3:
+	// SQL: SELECT AVG(`age`) AS `avg_age` FROM `test_model`;
+	// Args: []interface {}(nil)
+	// case4:
+	// SQL: SELECT COUNT(DISTINCT `age`) AS `age_cnt` FROM `test_model`;
+	// Args: []interface {}(nil)
 }
 
 func ExampleDB_Update() {

expression.go

@@ -20,15 +20,21 @@ type Expr interface {
 }
 
 // RawExpr uses string as Expr
-type RawExpr string
+type RawExpr struct {
+	raw  string
+	args []interface{}
+}
 
 // Raw just take expr as Expr
-func Raw(expr string) RawExpr {
-	return RawExpr(expr)
+func Raw(expr string, args ...interface{}) RawExpr {
+	return RawExpr{
+		raw:  expr,
+		args: args,
+	}
 }
 
 func (r RawExpr) expr() (string, error) {
-	return string(r), nil
+	return r.raw, nil
 }
 
 func (RawExpr) selected() {}

predicate.go

@@ -45,7 +45,7 @@ func (Predicate) expr() (string, error) {
 // Not indicates "NOT"
 func Not(p Predicate) Predicate {
 	return Predicate{
-		left:  RawExpr(""),
+		left:  Raw(""),
 		op:    opNot,
 		right: p,
 	}

select.go

@@ -172,7 +172,7 @@ func (s *Selector) buildSelectedList() error {
 				return err
 			}
 		case RawExpr:
-			_, _ = s.buffer.WriteString(string(expr))
+			s.buildRawExpr(expr)
 		}
 	}
 	return nil