Merge pull request #171 from doug-martin/v9.4.0-rc

v9.4.0

Author: doug-martin

HISTORY.md

@@ -1,3 +1,7 @@
+# v9.4.0
+
+* [ADDED] Ability to scan into struct fields from multiple tables [#160](https://github.com/doug-martin/goqu/issues/160)
+
 # v9.3.0
 
 * [ADDED] Using Update, Insert, or Delete datasets in sub selects and CTEs [#164](https://github.com/doug-martin/goqu/issues/164)

database_example_test.go

@@ -109,27 +109,27 @@ func ExampleDatabase_Dialect() {
 func ExampleDatabase_Exec() {
 	db := getDb()
 
-	_, err := db.Exec(`DROP TABLE "goqu_user"`)
+	_, err := db.Exec(`DROP TABLE "user_role"; DROP TABLE "goqu_user"`)
 	if err != nil {
-		fmt.Println("Error occurred while dropping table", err.Error())
+		fmt.Println("Error occurred while dropping tables", err.Error())
 	}
-	fmt.Println("Dropped table goqu_user")
+	fmt.Println("Dropped tables user_role and goqu_user")
 	// Output:
-	// Dropped table goqu_user
+	// Dropped tables user_role and goqu_user
 }
 
 func ExampleDatabase_ExecContext() {
 	db := getDb()
 	d := time.Now().Add(50 * time.Millisecond)
 	ctx, cancel := context.WithDeadline(context.Background(), d)
 	defer cancel()
-	_, err := db.ExecContext(ctx, `DROP TABLE "goqu_user"`)
+	_, err := db.ExecContext(ctx, `DROP TABLE "user_role"; DROP TABLE "goqu_user"`)
 	if err != nil {
-		fmt.Println("Error occurred while dropping table", err.Error())
+		fmt.Println("Error occurred while dropping tables", err.Error())
 	}
-	fmt.Println("Dropped table goqu_user")
+	fmt.Println("Dropped tables user_role and goqu_user")
 	// Output:
-	// Dropped table goqu_user
+	// Dropped tables user_role and goqu_user
 }
 
 func ExampleDatabase_From() {

docs/selecting.md

@@ -842,6 +842,78 @@ if err := db.From("user").Select("first_name").ScanStructs(&users); err != nil{
 fmt.Printf("\n%+v", users)
 ```
 
+`goqu` also supports scanning into multiple structs. In the example below we define a `Role` and `User` struct that could both be used individually to scan into. However, you can also create a new struct that adds both structs as fields that can be populated in a single query.
+
+**NOTE** When calling `ScanStructs` without a select already defined it will automatically only `SELECT` the columns found in the struct
+
+ ```go
+type Role struct {
+  Id     uint64 `db:"id"`
+	UserID uint64 `db:"user_id"`
+	Name   string `db:"name"`
+}
+type User struct {
+	Id        uint64 `db:"id"`
+	FirstName string `db:"first_name"`
+	LastName  string `db:"last_name"`
+}
+type UserAndRole struct {
+	User User `db:"goqu_user"` // tag as the "goqu_user" table
+	Role Role `db:"user_role"` // tag as "user_role" table
+}
+db := getDb()
+
+ds := db.
+	From("goqu_user").
+	Join(goqu.T("user_role"), goqu.On(goqu.I("goqu_user.id").Eq(goqu.I("user_role.user_id"))))
+var users []UserAndRole
+	// Scan structs will auto build the
+if err := ds.ScanStructs(&users); err != nil {
+	fmt.Println(err.Error())
+	return
+}
+for _, u := range users {
+	fmt.Printf("\n%+v", u)
+}
+```
+
+You can alternatively manually select the columns with the appropriate aliases using the `goqu.C` method to create the alias.
+
+```go
+type Role struct {
+	UserID uint64 `db:"user_id"`
+	Name   string `db:"name"`
+}
+type User struct {
+	Id        uint64 `db:"id"`
+	FirstName string `db:"first_name"`
+	LastName  string `db:"last_name"`
+	Role      Role   `db:"user_role"` // tag as "user_role" table
+}
+db := getDb()
+
+ds := db.
+	Select(
+		"goqu_user.id",
+		"goqu_user.first_name",
+		"goqu_user.last_name",
+		// alias the fully qualified identifier `C` is important here so it doesnt parse it
+		goqu.I("user_role.user_id").As(goqu.C("user_role.user_id")),
+		goqu.I("user_role.name").As(goqu.C("user_role.name")),
+	).
+	From("goqu_user").
+	Join(goqu.T("user_role"), goqu.On(goqu.I("goqu_user.id").Eq(goqu.I("user_role.user_id"))))
+
+var users []User
+if err := ds.ScanStructs(&users); err != nil {
+	fmt.Println(err.Error())
+	return
+}
+for _, u := range users {
+	fmt.Printf("\n%+v", u)
+}
+```
+
 <a name="scan-struct"></a>
 **[`ScanStruct`](http://godoc.org/github.com/doug-martin/goqu#SelectDataset.ScanStruct)**
 
@@ -869,6 +941,83 @@ if !found {
 }
 ```
 
+`goqu` also supports scanning into multiple structs. In the example below we define a `Role` and `User` struct that could both be used individually to scan into. However, you can also create a new struct that adds both structs as fields that can be populated in a single query.
+
+**NOTE** When calling `ScanStruct` without a select already defined it will automatically only `SELECT` the columns found in the struct
+
+ ```go
+type Role struct {
+	UserID uint64 `db:"user_id"`
+	Name   string `db:"name"`
+}
+type User struct {
+	ID        uint64 `db:"id"`
+	FirstName string `db:"first_name"`
+	LastName  string `db:"last_name"`
+}
+type UserAndRole struct {
+	User User `db:"goqu_user"` // tag as the "goqu_user" table
+	Role Role `db:"user_role"` // tag as "user_role" table
+}
+db := getDb()
+var userAndRole UserAndRole
+ds := db.
+	From("goqu_user").
+	Join(goqu.T("user_role"),goqu.On(goqu.I("goqu_user.id").Eq(goqu.I("user_role.user_id")))).
+	Where(goqu.C("first_name").Eq("Bob"))
+
+found, err := ds.ScanStruct(&userAndRole)
+if err != nil{
+  fmt.Println(err.Error())
+  return
+}
+if !found {
+  fmt.Println("No user found")
+} else {
+  fmt.Printf("\nFound user: %+v", user)
+}
+```
+
+You can alternatively manually select the columns with the appropriate aliases using the `goqu.C` method to create the alias.
+
+```go
+type Role struct {
+	UserID uint64 `db:"user_id"`
+	Name   string `db:"name"`
+}
+type User struct {
+	ID        uint64 `db:"id"`
+	FirstName string `db:"first_name"`
+	LastName  string `db:"last_name"`
+	Role      Role   `db:"user_role"` // tag as "user_role" table
+}
+db := getDb()
+var userAndRole UserAndRole
+ds := db.
+	Select(
+		"goqu_user.id",
+		"goqu_user.first_name",
+		"goqu_user.last_name",
+		// alias the fully qualified identifier `C` is important here so it doesnt parse it
+		goqu.I("user_role.user_id").As(goqu.C("user_role.user_id")),
+		goqu.I("user_role.name").As(goqu.C("user_role.name")),
+	).
+	From("goqu_user").
+	Join(goqu.T("user_role"),goqu.On(goqu.I("goqu_user.id").Eq(goqu.I("user_role.user_id")))).
+	Where(goqu.C("first_name").Eq("Bob"))
+
+found, err := ds.ScanStruct(&userAndRole)
+if err != nil{
+  fmt.Println(err.Error())
+  return
+}
+if !found {
+  fmt.Println("No user found")
+} else {
+  fmt.Printf("\nFound user: %+v", user)
+}
+```
+
 
 **NOTE** Using the `goqu.SetColumnRenameFunction` function, you can change the function that's used to rename struct fields when struct tags aren't defined
 
@@ -1037,3 +1186,4 @@ fmt.Printf("\nIds := %+v", ids)
 
 
 
+

exec/query_executor_test.go

@@ -5,6 +5,7 @@ import (
 	"database/sql"
 	"encoding/json"
 	"fmt"
+	"strings"
 	"testing"
 	"time"
 
@@ -415,8 +416,8 @@ func (qes *queryExecutorSuite) TestScanStructs_withIgnoredEmbeddedPointerStruct(
 	var composed []ComposedIgnoredPointerStruct
 	qes.NoError(e.ScanStructs(&composed))
 	qes.Equal([]ComposedIgnoredPointerStruct{
-		{StructWithTags: &StructWithTags{}, PhoneNumber: testPhone1, Age: testAge1},
-		{StructWithTags: &StructWithTags{}, PhoneNumber: testPhone2, Age: testAge2},
+		{PhoneNumber: testPhone1, Age: testAge1},
+		{PhoneNumber: testPhone2, Age: testAge2},
 	}, composed)
 }
 
@@ -944,6 +945,79 @@ func (qes *queryExecutorSuite) TestScanStruct() {
 	}, noTag)
 }
 
+func (qes *queryExecutorSuite) TestScanStruct_taggedStructs() {
+	type StructWithNoTags struct {
+		Address string
+		Name    string
+	}
+
+	type StructWithTags struct {
+		Address string `db:"address"`
+		Name    string `db:"name"`
+	}
+
+	type ComposedStruct struct {
+		StructWithTags
+		PhoneNumber string `db:"phone_number"`
+		Age         int64  `db:"age"`
+	}
+	type ComposedWithPointerStruct struct {
+		*StructWithTags
+		PhoneNumber string `db:"phone_number"`
+		Age         int64  `db:"age"`
+	}
+
+	type StructWithTaggedStructs struct {
+		NoTags          StructWithNoTags          `db:"notags"`
+		Tags            StructWithTags            `db:"tags"`
+		Composed        ComposedStruct            `db:"composedstruct"`
+		ComposedPointer ComposedWithPointerStruct `db:"composedptrstruct"`
+	}
+
+	db, mock, err := sqlmock.New()
+	qes.NoError(err)
+
+	cols := []string{
+		"notags.address", "notags.name",
+		"tags.address", "tags.name",
+		"composedstruct.address", "composedstruct.name", "composedstruct.phone_number", "composedstruct.age",
+		"composedptrstruct.address", "composedptrstruct.name", "composedptrstruct.phone_number", "composedptrstruct.age",
+	}
+
+	q := `SELECT` + strings.Join(cols, ", ") + ` FROM "items"`
+
+	mock.ExpectQuery(q).
+		WithArgs().
+		WillReturnRows(sqlmock.NewRows(cols).AddRow(
+			testAddr1, testName1,
+			testAddr2, testName2,
+			testAddr1, testName1, testPhone1, testAge1,
+			testAddr2, testName2, testPhone2, testAge2,
+		))
+
+	e := newQueryExecutor(db, nil, q)
+
+	var item StructWithTaggedStructs
+	found, err := e.ScanStruct(&item)
+	qes.NoError(err)
+	qes.True(found)
+	qes.Equal(StructWithTaggedStructs{
+		NoTags: StructWithNoTags{Address: testAddr1, Name: testName1},
+		Tags:   StructWithTags{Address: testAddr2, Name: testName2},
+		Composed: ComposedStruct{
+			StructWithTags: StructWithTags{Address: testAddr1, Name: testName1},
+			PhoneNumber:    testPhone1,
+			Age:            testAge1,
+		},
+		ComposedPointer: ComposedWithPointerStruct{
+			StructWithTags: &StructWithTags{Address: testAddr2, Name: testName2},
+			PhoneNumber:    testPhone2,
+			Age:            testAge2,
+		},
+	}, item)
+
+}
+
 func (qes *queryExecutorSuite) TestScanVals() {
 	db, mock, err := sqlmock.New()
 	qes.NoError(err)

exp/col.go

@@ -32,7 +32,12 @@ func NewColumnListExpression(vals ...interface{}) ColumnListExpression {
 				}
 				structCols := cm.Cols()
 				for _, col := range structCols {
-					cols = append(cols, ParseIdentifier(col))
+					i := ParseIdentifier(col)
+					var sc Expression = i
+					if i.IsQualified() {
+						sc = i.As(NewIdentifierExpression("", "", col))
+					}
+					cols = append(cols, sc)
 				}
 			} else {
 				panic(fmt.Sprintf("Cannot created expression from  %+v", val))

exp/exp.go

@@ -252,6 +252,14 @@ type (
 		Updateable
 		Distinctable
 		Castable
+		// returns true if this identifier has more more than on part (Schema, Table or Col)
+		//	"schema" -> true //cant qualify anymore
+		//	"schema.table" -> true
+		//	"table" -> false
+		// "schema"."table"."col" -> true
+		// "table"."col" -> true
+		// "col" -> false
+		IsQualified() bool
 		// Returns a new IdentifierExpression with the specified schema
 		Schema(string) IdentifierExpression
 		// Returns the current schema

exp/ident.go

@@ -33,6 +33,24 @@ func (i identifier) Clone() Expression {
 	return i.clone()
 }
 
+func (i identifier) IsQualified() bool {
+	schema, table, col := i.schema, i.table, i.col
+	switch c := col.(type) {
+	case string:
+		if c != "" {
+			return len(table) > 0 || len(schema) > 0
+		}
+	default:
+		if c != nil {
+			return len(table) > 0 || len(schema) > 0
+		}
+	}
+	if len(table) > 0 {
+		return len(schema) > 0
+	}
+	return false
+}
+
 // Sets the table on the current identifier
 //  I("col").Table("table") -> "table"."col" //postgres
 //  I("col").Table("table") -> `table`.`col` //mysql