Refactored interface & added tests

dbdrivers/interface.go

@@ -1,14 +1,16 @@
 package dbdrivers
 
+import "fmt"
+
 // Interface for a database driver. Functionality required to support a specific
 // database type (eg, MySQL, Postgres etc.)
 type Interface interface {
-	// Tables connects to the database and retrieves the table metadata for
-	// the given tables, or all tables if none are provided.
-	Tables(names ...string) ([]Table, error)
+	TableNames() ([]string, error)
+	Columns(tableName string) ([]Column, error)
+	PrimaryKeyInfo(tableName string) (*PrimaryKey, error)
+	ForeignKeyInfo(tableName string) ([]ForeignKey, error)
 
-	// TranslateColumnType takes a Database column type and returns a go column
-	// type.
+	// TranslateColumnType takes a Database column type and returns a go column type.
 	TranslateColumnType(Column) Column
 
 	// Open the database connection
@@ -34,7 +36,6 @@ type Table struct {
 type Column struct {
 	Name       string
 	Type       string
-	IsPrimaryKey bool
 	IsNullable bool
 }
 
@@ -52,3 +53,66 @@ type ForeignKey struct {
 	ForeignTable  string
 	ForeignColumn string
 }
+
+// Tables returns the table metadata for the given tables, or all tables if
+// no tables are provided.
+func Tables(db Interface, names ...string) ([]Table, error) {
+	var err error
+	if len(names) == 0 {
+		if names, err = db.TableNames(); err != nil {
+			fmt.Println("Unable to get table names.")
+			return nil, err
+		}
+	}
+
+	var tables []Table
+	for _, name := range names {
+		t := Table{Name: name}
+
+		if t.Columns, err = db.Columns(name); err != nil {
+			return nil, err
+			fmt.Println("Unable to get columnss.")
+		}
+
+		for i, c := range t.Columns {
+			t.Columns[i] = db.TranslateColumnType(c)
+		}
+
+		if t.PKey, err = db.PrimaryKeyInfo(name); err != nil {
+			fmt.Println("Unable to get primary key info.")
+			return nil, err
+		}
+
+		if t.FKeys, err = db.ForeignKeyInfo(name); err != nil {
+			fmt.Println("Unable to get foreign key info.")
+			return nil, err
+		}
+
+		setIsJoinTable(&t)
+
+		tables = append(tables, t)
+	}
+
+	return tables, nil
+}
+
+func setIsJoinTable(t *Table) {
+	if t.PKey == nil {
+		return
+	}
+
+	for _, c := range t.PKey.Columns {
+		found := false
+		for _, f := range t.FKeys {
+			if c == f.Column {
+				found = true
+				break
+			}
+		}
+		if !found {
+			return
+		}
+	}
+
+	t.IsJoinTable = true
+}

dbdrivers/interface_test.go

@@ -0,0 +1,31 @@
+package dbdrivers
+
+import "testing"
+
+func TestTables(t *testing.T) {
+
+}
+
+func TestSetIsJoinTable(t *testing.T) {
+	tests := []struct {
+		Pkey   []string
+		Fkey   []string
+		Should bool
+	}{
+		{Pkey: []string{"one"}, Fkey: []string{"one"}, Should: true},
+	}
+
+	for i, test := range tests {
+		var table Table
+
+		table.PKey = &PrimaryKey{Columns: test.Pkey}
+		for _, k := range test.Fkey {
+			table.FKeys = append(table.FKeys, ForeignKey{Column: k})
+		}
+
+		setIsJoinTable(&table)
+		if is := table.IsJoinTable; is != test.Should {
+			t.Errorf("%d) want: %t, got: %t\nTest: %#v", i, test.Should, is, test)
+		}
+	}
+}

dbdrivers/postgres_driver.go

@@ -44,47 +44,11 @@ func (p *PostgresDriver) Close() {
 	p.dbConn.Close()
 }
 
-// Tables returns the table metadata for the given tables, or all tables if
-// no tables are provided.
-func (p *PostgresDriver) Tables(names ...string) ([]Table, error) {
-	var err error
-	if len(names) == 0 {
-		if names, err = p.tableNames(); err != nil {
-			fmt.Println("Unable to get table names.")
-			return nil, err
-		}
-	}
-
-	var tables []Table
-	for _, name := range names {
-		t := Table{Name: name}
-
-		if t.Columns, err = p.columns(name); err != nil {
-			fmt.Println("Unable to get columnss.")
-			return nil, err
-		}
-
-		if t.PKey, err = p.primaryKeyInfo(name); err != nil {
-			fmt.Println("Unable to get primary key info.")
-			return nil, err
-		}
-
-		if t.FKeys, err = p.foreignKeyInfo(name); err != nil {
-			fmt.Println("Unable to get foreign key info.")
-			return nil, err
-		}
-
-		tables = append(tables, t)
-	}
-
-	return tables, nil
-}
-
 // tableNames connects to the postgres database and
 // retrieves all table names from the information_schema where the
 // table schema is public. It excludes common migration tool tables
 // such as gorp_migrations
-func (p *PostgresDriver) tableNames() ([]string, error) {
+func (p *PostgresDriver) TableNames() ([]string, error) {
 	var names []string
 
 	rows, err := p.dbConn.Query(`select table_name from
@@ -111,23 +75,12 @@ func (p *PostgresDriver) tableNames() ([]string, error) {
 // from the database information_schema.columns. It retrieves the column names
 // and column types and returns those as a []Column after TranslateColumnType()
 // converts the SQL types to Go types, for example: "varchar" to "string"
-func (p *PostgresDriver) columns(tableName string) ([]Column, error) {
+func (p *PostgresDriver) Columns(tableName string) ([]Column, error) {
 	var columns []Column
 
 	rows, err := p.dbConn.Query(`
-		SELECT c.column_name, c.data_type, c.is_nullable,
-		CASE WHEN pk.column_name IS NOT NULL THEN 'PRIMARY KEY' ELSE '' END AS KeyType
-		FROM information_schema.columns c
-		LEFT JOIN (
-		  SELECT ku.table_name, ku.column_name
-		  FROM information_schema.table_constraints AS tc
-		  INNER JOIN information_schema.key_column_usage AS ku
-		    ON tc.constraint_type = 'PRIMARY KEY'
-		    AND tc.constraint_name = ku.constraint_name
-		) pk
-		ON c.table_name = pk.table_name
-		AND c.column_name = pk.column_name
-		WHERE c.table_name=$1
+		SELECT column_name, data_type, is_nullable from
+    information_schema.columns WHERE table_name=$1
 	`, tableName)
 
 	if err != nil {
@@ -136,16 +89,15 @@ func (p *PostgresDriver) columns(tableName string) ([]Column, error) {
 
 	defer rows.Close()
 	for rows.Next() {
-		var colName, colType, isNullable, isPrimary string
-		if err := rows.Scan(&colName, &colType, &isNullable, &isPrimary); err != nil {
+		var colName, colType, isNullable string
+		if err := rows.Scan(&colName, &colType, &isNullable); err != nil {
 			return nil, err
 		}
-		column := p.TranslateColumnType(Column{
+		column := Column{
 			Name:       colName,
 			Type:       colType,
 			IsNullable: isNullable == "YES",
-			IsPrimaryKey: isPrimary == "PRIMARY KEY",
-		})
+		}
 		columns = append(columns, column)
 	}
 
@@ -153,7 +105,7 @@ func (p *PostgresDriver) columns(tableName string) ([]Column, error) {
 }
 
 // primaryKeyInfo looks up the primary key for a table.
-func (p *PostgresDriver) primaryKeyInfo(tableName string) (*PrimaryKey, error) {
+func (p *PostgresDriver) PrimaryKeyInfo(tableName string) (*PrimaryKey, error) {
 	pkey := &PrimaryKey{}
 	var err error
 
@@ -199,7 +151,7 @@ func (p *PostgresDriver) primaryKeyInfo(tableName string) (*PrimaryKey, error) {
 }
 
 // foreignKeyInfo retrieves the foreign keys for a given table name.
-func (p *PostgresDriver) foreignKeyInfo(tableName string) ([]ForeignKey, error) {
+func (p *PostgresDriver) ForeignKeyInfo(tableName string) ([]ForeignKey, error) {
 	var fkeys []ForeignKey
 
 	query := `