Feat: add insert function and test for it

.CHANGELOG.md

@@ -10,3 +10,4 @@
 - [Support Aggregate Functions](https://github.com/gotomicro/eql/pull/37)
 - [Updater implementation, excluding WHERE clause](https://github.com/gotomicro/eql/pull/36)
 - [Force test and lint in pre-push](https://github.com/gotomicro/eql/pull/35)
+- [Insert implementation ](https://github.com/gotomicro/eql/pull/38)

db.go

@@ -24,7 +24,7 @@ type DBOption func(db *DB)
 
 // DB represents a database
 type DB struct {
-	metaRegistry MetaRegistry
+	metaRegistry   MetaRegistry
 	dialect        Dialect
 	nullAssertFunc NullAssertFunc
 }
@@ -65,14 +65,16 @@ func (db *DB) Update(table interface{}) *Updater {
 
 // Insert generate Inserter to builder insert query
 func (db *DB) Insert() *Inserter {
-	return &Inserter{}
+	return &Inserter{
+		builder: db.builder(),
+	}
 }
 
 func (db *DB) builder() builder {
 	return builder{
 		registry: db.metaRegistry,
-		dialect: db.dialect,
-		buffer: &strings.Builder{},
+		dialect:  db.dialect,
+		buffer:   &strings.Builder{},
 	}
 }
 
@@ -97,7 +99,7 @@ func NilAsNullFunc(val interface{}) bool {
 
 // ZeroAsNullFunc means "zero value = null"
 func ZeroAsNullFunc(val interface{}) bool {
-	if val == nil{
+	if val == nil {
 		return true
 	}
 	switch v := val.(type) {

insert.go

@@ -14,34 +14,111 @@
 
 package eql
 
+import (
+	"errors"
+	"fmt"
+	"reflect"
+)
+
 // Inserter is used to construct an insert query
 type Inserter struct {
+	builder
+	columns []string
+	values  []interface{}
 }
 
 func (i *Inserter) Build() (*Query, error) {
-	panic("implement me")
+	var err error
+	if len(i.values) == 0 {
+		return &Query{}, errors.New("no values")
+	}
+	i.buffer.WriteString("INSERT INTO ")
+	i.meta, err = i.registry.Get(i.values[0])
+	if err != nil {
+		return &Query{}, err
+	}
+	i.quote(i.meta.tableName)
+	i.buffer.WriteString("(")
+	fields, err := i.buildColumns()
+	if err != nil {
+		return &Query{}, err
+	}
+	i.buffer.WriteString(")")
+	i.buffer.WriteString(" VALUES")
+	for index, value := range i.values {
+		i.buffer.WriteString("(")
+		refVal := reflect.ValueOf(value).Elem()
+		for j, v := range fields {
+			field := refVal.FieldByName(v.fieldName)
+			if !field.IsValid() {
+				return &Query{}, fmt.Errorf("invalid column %s", v.fieldName)
+			}
+			val := field.Interface()
+			i.parameter(val)
+			if j != len(fields)-1 {
+				i.comma()
+			}
+		}
+		i.buffer.WriteString(")")
+		if index != len(i.values)-1 {
+			i.comma()
+		}
+	}
+	i.end()
+	return &Query{SQL: i.buffer.String(), Args: i.args}, nil
 }
 
 // Columns specifies the columns that need to be inserted
 // if cs is empty, all columns will be inserted except auto increment columns
-func (db *DB) Columns(cs ...string) *Inserter {
-	panic("implements me")
+func (i *Inserter) Columns(cs ...string) *Inserter {
+	i.columns = cs
+	return i
 }
 
 // Values specify the rows
 // all the elements must be the same structure
 func (i *Inserter) Values(values ...interface{}) *Inserter {
-	panic("implement me")
+	i.values = values
+	return i
 }
 
 // OnDuplicateKey generate MysqlUpserter
 // if the dialect is not MySQL, it will panic
 func (i *Inserter) OnDuplicateKey() *MysqlUpserter {
+
 	panic("implement me")
 }
 
 // OnConflict generate PgSQLUpserter
 // if the dialect is not PgSQL, it will panic
 func (i *Inserter) OnConflict(cs ...string) *PgSQLUpserter {
+
 	panic("implement me")
 }
+
+func (i *Inserter) buildColumns() ([]*ColumnMeta, error) {
+	cs := i.meta.columns
+	if len(i.columns) != 0 {
+		cs = make([]*ColumnMeta, 0, len(i.columns))
+		for index, value := range i.columns {
+			v, isOk := i.meta.fieldMap[value]
+			if !isOk {
+				return cs, fmt.Errorf("invalid column %s", value)
+			}
+			i.quote(v.columnName)
+			if index != len(i.columns)-1 {
+				i.comma()
+			}
+			cs = append(cs, v)
+		}
+	} else {
+		for index, value := range i.meta.columns {
+			i.quote(value.columnName)
+			if index != len(cs)-1 {
+				i.comma()
+			}
+		}
+	}
+	return cs, nil
+
+}

insert_test.go

@@ -0,0 +1,105 @@
+// Copyright 2021 gotomicro
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+package eql
+
+import (
+	"errors"
+	"github.com/stretchr/testify/assert"
+	"testing"
+	"time"
+)
+
+func TestInserter_Values(t *testing.T) {
+	type User struct {
+		Id        int64
+		FirstName string
+		Ctime     time.Time
+	}
+	type Order struct {
+		Id    int64
+		Name  string
+		Price int64
+	}
+
+	n := time.Now()
+	u := &User{
+		Id:        12,
+		FirstName: "Tom",
+		Ctime:     n,
+	}
+	u1 := &User{
+		Id:        13,
+		FirstName: "Jerry",
+		Ctime:     n,
+	}
+	o1 := &Order{
+		Id:    14,
+		Name:  "Hellen",
+		Price: 200,
+	}
+	testCases := []CommonTestCase{
+		{
+			name:    "no examples of values",
+			builder: New().Insert().Values(),
+			wantErr: errors.New("no values"),
+		},
+		{
+			name:     "single example of values",
+			builder:  New().Insert().Values(u),
+			wantSql:  "INSERT INTO `user`(`id`,`first_name`,`ctime`) VALUES(?,?,?);",
+			wantArgs: []interface{}{int64(12), "Tom", n},
+		},
+
+		{
+			name:     "multiple values of same type",
+			builder:  New().Insert().Values(u, u1),
+			wantSql:  "INSERT INTO `user`(`id`,`first_name`,`ctime`) VALUES(?,?,?),(?,?,?);",
+			wantArgs: []interface{}{int64(12), "Tom", n, int64(13), "Jerry", n},
+		},
+
+		{
+			name:     "no example of a whole columns",
+			builder:  New().Insert().Columns("Id", "FirstName").Values(u),
+			wantSql:  "INSERT INTO `user`(`id`,`first_name`) VALUES(?,?);",
+			wantArgs: []interface{}{int64(12), "Tom"},
+		},
+		{
+			name:    "an example with invalid columns",
+			builder: New().Insert().Columns("id", "FirstName").Values(u),
+			wantErr: errors.New("invalid column id"),
+		},
+		{
+			name:     "no whole columns and multiple values of same type",
+			builder:  New().Insert().Columns("Id", "FirstName").Values(u, u1),
+			wantSql:  "INSERT INTO `user`(`id`,`first_name`) VALUES(?,?),(?,?);",
+			wantArgs: []interface{}{int64(12), "Tom", int64(13), "Jerry"},
+		},
+		{
+			name:    "multiple values of invalid column",
+			builder: New().Insert().Values(u, o1),
+			wantErr: errors.New("invalid column FirstName"),
+		},
+	}
+
+	for _, tc := range testCases {
+
+		c := tc
+		t.Run(tc.name, func(t *testing.T) {
+			q, err := c.builder.Build()
+			assert.Equal(t, c.wantErr, err)
+			assert.Equal(t, c.wantSql, q.SQL)
+			assert.Equal(t, c.wantArgs, q.Args)
+		})
+	}
+}