Add ClumpRepository with implementations

repository/clump.go

@@ -0,0 +1,96 @@
+package repository
+
+import (
+	"errors"
+
+	"github.com/google/uuid"
+)
+
+// ErrPasteNotInDatabase is returned when one calls PutClump with pastes that are not in the database.
+var ErrPasteNotInDatabase = errors.New("repository: given pastes are not in the database")
+
+// Clump represents a group ("clump") of pastes
+type Clump struct {
+	ID     int
+	Title  string
+	Handle uuid.UUID
+	Pastes []Paste
+}
+
+// ClumpRepository puts/gets a clump from the database
+type ClumpRepository interface {
+	// GetClump gets a clump from the database
+	GetClump(handle uuid.UUID) (Clump, error)
+	// GetClump gets a clump from the database
+	PutClump(title string, pastes ...Paste) (Clump, error)
+}
+
+// GetClump gets a clump and all of its associated pastes
+func (db *DatabaseConnector) GetClump(handle uuid.UUID) (Clump, error) {
+	pasteRows, err := db.DB.Query("SELECT paste.*, clump.* FROM paste JOIN CLUMP USING (clumpID) WHERE handle = $1", handle.String())
+	if err != nil {
+		return Clump{}, err
+	}
+
+	clump := Clump{
+		Pastes: []Paste{},
+	}
+
+	for pasteRows.Next() {
+		paste := Paste{}
+		// Per the docs, "The number of values in dest must be the same as the number of columns in Rows."
+		// Because the clump result will always be the same, we can just pull it on each row and update the same struct
+		pasteRows.Scan(&paste.ID, &paste.Filename, &paste.Handle, &paste.ClumpID, &clump.ID, &clump.Title, &clump.Handle)
+		clump.Pastes = append(clump.Pastes, paste)
+	}
+
+	return clump, pasteRows.Err()
+}
+
+// PutClump puts a clump into the database.
+// All given pastes must have already been inserted to the database. Returns ErrPasteNotInDatabase if condition isn't met.
+func (db *DatabaseConnector) PutClump(title string, pastes ...Paste) (Clump, error) {
+	handle, err := uuid.NewUUID()
+	if err != nil {
+		return Clump{}, err
+	}
+
+	clump := Clump{
+		Handle: handle,
+	}
+
+	tx, err := db.DB.Begin()
+	insertResult := tx.QueryRow("INSERT INTO clump VALUES(DEFAULT, $1, $2) RETURNING clumpID", title, handle.String())
+	err = insertResult.Scan(&clump.ID)
+	if err != nil {
+		tx.Rollback()
+		return Clump{}, err
+	}
+
+	err = db.addPastesToClump(tx, clump.ID, pastes)
+	if err != nil {
+		tx.Rollback()
+		return Clump{}, err
+	}
+
+	return clump, tx.Commit()
+}
+
+func (db *DatabaseConnector) addPastesToClump(ex executor, clumpID int, pastes []Paste) error {
+	for _, paste := range pastes {
+		paste.ClumpID = clumpID
+		result, err := db.updatePaste(ex, paste)
+		if err != nil {
+			return err
+		}
+
+		numRows, err := result.RowsAffected()
+		if err != nil {
+			return err
+		} else if numRows == 0 {
+			return ErrPasteNotInDatabase
+		}
+	}
+
+	return nil
+}

repository/paste.go

@@ -1,6 +1,10 @@
 package repository
 
-import "github.com/google/uuid"
+import (
+	"database/sql"
+
+	"github.com/google/uuid"
+)
 
 // Paste represents a paste that the user has stored in the database
 type Paste struct {
@@ -55,7 +59,11 @@ func (db *DatabaseConnector) PutPaste(filename string) (Paste, error) {
 // UpdatePaste allows for a paste to be updated.
 // Currently, only the filename and clump id can be updated
 func (db *DatabaseConnector) UpdatePaste(paste Paste) error {
-	_, err := db.DB.Exec("UPDATE paste SET filename = $1, clumpID = $2 WHERE pasteID = $3", paste.Filename, paste.ClumpID, paste.ID)
+	_, err := db.updatePaste(db.DB, paste)
 
 	return err
 }
+
+func (db *DatabaseConnector) updatePaste(ex executor, paste Paste) (sql.Result, error) {
+	return db.DB.Exec("UPDATE paste SET filename = $1, clumpID = $2 WHERE pasteID = $3", paste.Filename, paste.ClumpID, paste.ID)
+}