Qlite: Return OptionalRow instead of Row?, add ability to remove columns on version upgrade

4 files changed, 77 insertions, 37 deletions

diff --git a/qlite/src/database.vala b/qlite/src/database.vala
index 6d26b2b4..9fea7708 100644
--- a/qlite/src/database.vala
+++ b/qlite/src/database.vala
@@ -51,15 +51,19 @@ public class Database {
         meta_table.create_table_at_version(expected_version);
         long old_version = 0;
         try {
-            Row? row = meta_table.row_with(meta_name, "version");
-            old_version = row == null ? -1 : (long) row[meta_int_val];
+            old_version = meta_table.row_with(meta_name, "version")[meta_int_val, -1];
         } catch (DatabaseError e) {
             old_version = -1;
         }
-        foreach (Table t in tables) {
-            t.create_table_at_version(old_version);
-        }
-        if (expected_version != old_version) {
+        if (old_version == -1) {
+            foreach (Table t in tables) {
+                t.create_table_at_version(expected_version);
+            }
+            meta_table.insert().value(meta_name, "version").value(meta_int_val, expected_version).perform();
+        } else if (expected_version != old_version) {
+            foreach (Table t in tables) {
+                t.create_table_at_version(old_version);
+            }
             foreach (Table t in tables) {
                 t.add_columns_for_version(old_version, expected_version);
             }
@@ -117,9 +121,9 @@ public class Database {
         return new DeleteBuilder(this);
     }
 
-    public Row.RowIterator query_sql(string sql, string[]? args = null) throws DatabaseError {
+    public RowIterator query_sql(string sql, string[]? args = null) throws DatabaseError {
         ensure_init();
-        return new Row.RowIterator(this, sql, args);
+        return new RowIterator(this, sql, args);
     }
 
     public Statement prepare(string sql) throws DatabaseError {
diff --git a/qlite/src/query_builder.vala b/qlite/src/query_builder.vala
index 65cbb8f6..37f9b261 100644
--- a/qlite/src/query_builder.vala
+++ b/qlite/src/query_builder.vala
@@ -131,20 +131,20 @@ public class QueryBuilder : StatementBuilder {
     public int64 count() throws DatabaseError {
         this.column_selector = @"COUNT($column_selector) AS count";
         this.single_result = true;
-        return row().get_integer("count");
+        return row_().get_integer("count");
     }
 
-    public Row? row() throws DatabaseError {
+    private Row? row_() throws DatabaseError {
         if (!single_result) throw new DatabaseError.NON_UNIQUE("query is not suited to return a single row, but row() was called.");
         return iterator().next_value();
     }
 
+    public RowOption row() throws DatabaseError {
+        return new RowOption(row_());
+    }
+
     public T get<T>(Column<T> field) throws DatabaseError {
-        Row row = row();
-        if (row != null) {
-            return row[field];
-        }
-        return null;
+        return row()[field];
     }
 
     public override Statement prepare() throws DatabaseError {
@@ -155,8 +155,8 @@ public class QueryBuilder : StatementBuilder {
         return stmt;
     }
 
-    public Row.RowIterator iterator() throws DatabaseError {
-        return new Row.RowIterator.from_query_builder(this);
+    public RowIterator iterator() throws DatabaseError {
+        return new RowIterator.from_query_builder(this);
     }
 
     class OrderingTerm {
diff --git a/qlite/src/row.vala b/qlite/src/row.vala
index ff98405f..de10751f 100644
--- a/qlite/src/row.vala
+++ b/qlite/src/row.vala
@@ -50,29 +50,46 @@ public class Row {
     public bool has_real(string field) {
         return real_map.has_key(field) && real_map[field] != null;
     }
+}
 
-    public class RowIterator {
-        private Statement stmt;
+public class RowIterator {
+    private Statement stmt;
 
-        public RowIterator.from_query_builder(QueryBuilder query) throws DatabaseError {
-            this.stmt = query.prepare();
-        }
+    public RowIterator.from_query_builder(QueryBuilder query) throws DatabaseError {
+        this.stmt = query.prepare();
+    }
 
-        public RowIterator(Database db, string sql, string[]? args = null) throws DatabaseError {
-            this.stmt = db.prepare(sql);
-            if (args != null) {
-                for (int i = 0; i < args.length; i++) {
-                    stmt.bind_text(i, sql, sql.length);
-                }
+    public RowIterator(Database db, string sql, string[]? args = null) throws DatabaseError {
+        this.stmt = db.prepare(sql);
+        if (args != null) {
+            for (int i = 0; i < args.length; i++) {
+                stmt.bind_text(i, sql, sql.length);
             }
         }
+    }
 
-        public Row? next_value() {
-            if (stmt.step() == Sqlite.ROW) {
-                return new Row(stmt);
-            }
-            return null;
+    public Row? next_value() {
+        if (stmt.step() == Sqlite.ROW) {
+            return new Row(stmt);
         }
+        return null;
+    }
+}
+
+public class RowOption {
+    public Row? inner { get; private set; }
+
+    public RowOption(Row? row) {
+        this.inner = row;
+    }
+
+    public bool is_present() {
+        return inner != null;
+    }
+
+    public T get<T>(Column<T> field, T def = null) {
+        if (inner == null || field.is_null(inner)) return def;
+        return field[inner];
     }
 }
 
diff --git a/qlite/src/table.vala b/qlite/src/table.vala
index 7396136e..357e18d4 100644
--- a/qlite/src/table.vala
+++ b/qlite/src/table.vala
@@ -22,7 +22,7 @@ public class Table {
         if (constraints == null) constraints = ""; else constraints += ", ";
         constraints += "UNIQUE (";
         bool first = true;
-        foreach(Column c in columns) {
+        foreach (Column c in columns) {
             if (!first) constraints += ", ";
             constraints += c.name;
             first = false;
@@ -57,7 +57,7 @@ public class Table {
         return db.delete().from(this);
     }
 
-    public Row? row_with<T>(Column<T> column, T value) throws DatabaseError {
+    public RowOption row_with<T>(Column<T> column, T value) throws DatabaseError {
         ensure_init();
         if (!column.unique && !column.primary_key) throw new DatabaseError.NON_UNIQUE(@"$(column.name) is not suited to identify a row, but used with row_with()");
         return select().with(column, "=", value).row();
@@ -74,7 +74,7 @@ public class Table {
     public void create_table_at_version(long version) throws DatabaseError {
         ensure_init();
         string sql = @"CREATE TABLE IF NOT EXISTS $name (";
-        for(int i = 0; i < columns.length; i++) {
+        for (int i = 0; i < columns.length; i++) {
             Column c = columns[i];
             if (c.min_version <= version && c.max_version >= version) {
                 sql += @"$(i > 0 ? "," : "") $c";
@@ -97,7 +97,26 @@ public class Table {
     }
 
     public void delete_columns_for_version(long old_version, long new_version) throws DatabaseError {
-        // TODO: Rename old table, create table at new_version, transfer data
+        bool column_deletion_required = false;
+        string column_list = null;
+        foreach (Column c in columns) {
+            if (c.min_version <= new_version && c.max_version >= new_version) {
+                if (column_list == null) {
+                    column_list = c.name;
+                } else {
+                    column_list += ", " + c.name;
+                }
+            }
+            if (!(c.min_version <= new_version && c.max_version >= new_version) && c.min_version <= old_version && c.max_version >= old_version) {
+                column_deletion_required = true;
+            }
+        }
+        if (column_deletion_required) {
+            db.exec(@"ALTER TABLE $name RENAME TO _$(name)_$old_version");
+            create_table_at_version(new_version);
+            db.exec(@"INSERT INTO $name ($column_list) SELECT $column_list FROM _$(name)_$old_version");
+            db.exec(@"DROP TABLE _$(name)_$old_version");
+        }
     }
 }