# class SQLite3::Backup

### Public Class Methods

SQLite3::Backup.new(dstdb, dstname, srcdb, srcname) click to toggle source

Initialize backup the backup.

dstdb:

    the destination SQLite3::Database object.

dstname:

    the destination's database name.

srcdb:

    the source SQLite3::Database object.

srcname:

    the source's database name.

The database name is “main”, “temp”, or the name specified in an ATTACH statement.

This feature requires SQLite 3.6.11 or later.

    require 'sqlite3'
    sdb = SQLite3::Database.new('src.sqlite3')

    ddb = SQLite3::Database.new(':memory:')
    b = SQLite3::Backup.new(ddb, 'main', sdb, 'main')
    p [b.remaining, b.pagecount] # invalid value; for example [0, 0]
    begin
      p b.step(1) #=> OK or DONE
      p [b.remaining, b.pagecount]
    end while b.remaining > 0
    b.finish

    ddb = SQLite3::Database.new(':memory:')
    b = SQLite3::Backup.new(ddb, 'main', sdb, 'main')
    b.step(-1) #=> DONE
    b.finish

    static VALUE initialize(VALUE self, VALUE dstdb, VALUE dstname, VALUE srcdb, VALUE srcname)
    {
      sqlite3BackupRubyPtr ctx;
      sqlite3RubyPtr ddb_ctx, sdb_ctx;
      sqlite3_backup *pBackup;

      Data_Get_Struct(self, sqlite3BackupRuby, ctx);
      Data_Get_Struct(dstdb, sqlite3Ruby, ddb_ctx);
      Data_Get_Struct(srcdb, sqlite3Ruby, sdb_ctx);

      if(!sdb_ctx->db)
        rb_raise(rb_eArgError, "cannot backup from a closed database");
      if(!ddb_ctx->db)
        rb_raise(rb_eArgError, "cannot backup to a closed database");

      pBackup = sqlite3_backup_init(ddb_ctx->db, StringValuePtr(dstname),
        sdb_ctx->db, StringValuePtr(srcname));
      if( pBackup ){
        ctx->p = pBackup;
      }
      else {
        CHECK(ddb_ctx->db, sqlite3_errcode(ddb_ctx->db));
      }

      return self;
    }

### Public Instance Methods

SQLite3::Backup#finish click to toggle source

Destroy the backup object.

    static VALUE finish(VALUE self)
    {
      sqlite3BackupRubyPtr ctx;

      Data_Get_Struct(self, sqlite3BackupRuby, ctx);
      REQUIRE_OPEN_BACKUP(ctx);
      (void)sqlite3_backup_finish(ctx->p);
      ctx->p = NULL;
      return Qnil;
    }

SQLite3::Backup#pagecount click to toggle source

Returns the total number of pages in the source database file.

Note that the value is only updated after step() is called, so before calling step() returned value is invalid.

    static VALUE pagecount(VALUE self)
    {
      sqlite3BackupRubyPtr ctx;

      Data_Get_Struct(self, sqlite3BackupRuby, ctx);
      REQUIRE_OPEN_BACKUP(ctx);
      return INT2NUM(sqlite3_backup_pagecount(ctx->p));
    }

SQLite3::Backup#remaining click to toggle source

Returns the number of pages still to be backed up.

Note that the value is only updated after step() is called, so before calling step() returned value is invalid.

    static VALUE remaining(VALUE self)
    {
      sqlite3BackupRubyPtr ctx;

      Data_Get_Struct(self, sqlite3BackupRuby, ctx);
      REQUIRE_OPEN_BACKUP(ctx);
      return INT2NUM(sqlite3_backup_remaining(ctx->p));
    }

SQLite3::Backup#step(nPage) click to toggle source

Copy database pages up to `nPage`. If negative, copy all remaining source pages.

If all pages are copied, it returns SQLite3::Constants::ErrorCode::DONE. When coping is not done, it returns SQLite3::Constants::ErrorCode::OK. When some errors occur, it returns the error code.

    static VALUE step(VALUE self, VALUE nPage)
    {
      sqlite3BackupRubyPtr ctx;
      int status;

      Data_Get_Struct(self, sqlite3BackupRuby, ctx);
      REQUIRE_OPEN_BACKUP(ctx);
      status = sqlite3_backup_step(ctx->p, NUM2INT(nPage));
      return INT2NUM(status);
    }