Module: SQLite::API

aggregate_context( func ) → hash click to toggle source

Returns the aggregate context for the given function. This context is a Hash object that is allocated on demand and is available only to the current invocation of the function. It may be used by aggregate functions to accumulate data over multiple rows, prior to being finalized.

The func parameter must be an opaque function handle as given to the callbacks for create_aggregate.

See create_aggregate and aggregate_count.

static VALUE
static_api_aggregate_context( VALUE module, VALUE func )
{
  sqlite_func *func_ptr;
  VALUE *ptr;

  GetFunc( func_ptr, func );

  /* FIXME: pointers to VALUEs...how nice is the GC about this kind of
   * thing? Especially when someone else frees the memory? */

  ptr = (VALUE*)sqlite_aggregate_context( func_ptr, sizeof(VALUE) );

  if( *ptr == 0 )
    *ptr = rb_hash_new();

  return *ptr;
}

aggregate_count( func ) → fixnum click to toggle source

Returns the number of rows that have been processed so far by the current aggregate function. This always includes the current row, so that number that is returned will always be at least 1.

The func parameter must be an opaque function handle as given to the callbacks for create_aggregate.

static VALUE
static_api_aggregate_count( VALUE module, VALUE func )
{
  sqlite_func *func_ptr;

  GetFunc( func_ptr, func );
  return INT2FIX( sqlite_aggregate_count( func_ptr ) );
}

busy_handler( db, handler ) → nil click to toggle source

Installs a callback to be invoked whenever a request cannot be honored because a database is busy. The handler should take two parameters: a string naming the resource that was being accessed, and an integer indicating how many times the current request has failed due to the resource being busy.

If the handler returns false, the operation will be aborted, with a SQLite::BusyException being raised. Otherwise, SQLite will attempt to access the resource again.

See busy_timeout for an easier way to manage the common case.

static VALUE
static_api_busy_handler( VALUE module, VALUE db, VALUE handler )
{
  sqlite *handle;

  GetDB( handle, db );
  if( handler == Qnil )
  {
    sqlite_busy_handler( handle, NULL, NULL );
  }
  else
  {
    if( !rb_obj_is_kind_of( handler, rb_cProc ) )
    {
      rb_raise( rb_eArgError, "handler must be a proc" );
    }

    sqlite_busy_handler( handle, static_busy_handler, (void*)handler );
  }

  return Qnil;
}

busy_timeout( db, ms ) → nil click to toggle source

Specifies the number of milliseconds that SQLite should wait before retrying to access a busy resource. Specifying zero milliseconds restores the default behavior.

static VALUE
static_api_busy_timeout( VALUE module, VALUE db, VALUE ms )
{
  sqlite *handle;

  GetDB( handle, db );
  Check_Type( ms, T_FIXNUM );

  sqlite_busy_timeout( handle, FIX2INT( ms ) );

  return Qnil;
}

changes( db ) → fixnum click to toggle source

Returns the number of changed rows affected by the last operation. (Note: doing a "delete from table" without a where clause does not affect the result of this method--see the documentation for SQLite itself for the reason behind this.)

static VALUE
static_api_changes( VALUE module, VALUE db )
{
  sqlite *handle;

  GetDB( handle, db );

  return INT2FIX( sqlite_changes( handle ) );
}

close( db ) click to toggle source

Closes the given opaque database handle. The handle must be one that was returned by a call to open.

static VALUE
static_api_close( VALUE module, VALUE db )
{
  sqlite *handle;

  /* FIXME: should this be executed atomically? */
  GetDB( handle, db );
  sqlite_close( handle );

  /* don't need to free the handle anymore */
  RDATA(db)->dfree = NULL;
  RDATA(db)->data = NULL;

  return Qnil;
}

compile( db, sql ) → [ vm, remainder ] click to toggle source

Compiles the given SQL statement and returns a new virtual machine handle for executing it. Returns a tuple: [ vm, remainder ], where remainder is any text that follows the first complete SQL statement in the sql parameter.

static VALUE
static_api_compile( VALUE module, VALUE db, VALUE sql )
{
  sqlite     *handle;
  sqlite_vm  *vm;
  char       *errmsg;
  const char *sql_tail;
  int         result;
  VALUE       tuple;

  GetDB( handle, db );
  Check_Type( sql, T_STRING );

  result = sqlite_compile( handle,
                           StringValuePtr( sql ),
                           &sql_tail,
                           &vm,
                           &errmsg );

  if( result != SQLITE_OK )
  {
    static_raise_db_error2( result, &errmsg );
    /* "raise" does not return */
  }

  tuple = rb_ary_new();
  rb_ary_push( tuple, Data_Wrap_Struct( rb_cData, NULL, static_free_vm, vm ) );
  rb_ary_push( tuple, rb_str_new2( sql_tail ) );

  return tuple;
}

complete( sql ) → true | false click to toggle source

Returns true if the given SQL text is complete (parsable), and false otherwise.

static VALUE
static_api_complete( VALUE module, VALUE sql )
{
  Check_Type( sql, T_STRING );
  return ( sqlite_complete( StringValuePtr( sql ) ) ? Qtrue : Qfalse );
}

create_aggregate( db, name, args, step, finalize ) → nil click to toggle source

Defines a new aggregate function that may be invoked from within an SQL statement. The args parameter specifies how many arguments the function expects--use -1 to specify variable arity.

The step parameter specifies a proc object that will be invoked for each row that the function processes. It should accept an opaque handle to the function object, followed by its expected arguments:

step = proc do |func, *args|
  ...
end

The finalize parameter specifies a proc object that will be invoked after all rows have been processed. This gives the function an opportunity to aggregate and finalize the results. It should accept a single parameter: the opaque function handle:

finalize = proc do |func|
  ...
end

The function object is used when calling the set_result, set_result_error, aggregate_context, and aggregate_count methods.

static VALUE
static_api_create_aggregate( VALUE module, VALUE db, VALUE name, VALUE n,
  VALUE step, VALUE finalize )
{
  sqlite *handle;
  int     result;
  VALUE   data;

  GetDB( handle, db );
  Check_Type( name, T_STRING );
  Check_Type( n, T_FIXNUM );
  if( !rb_obj_is_kind_of( step, rb_cProc ) )
  {
    rb_raise( rb_eArgError, "step must be a proc" );
  }
  if( !rb_obj_is_kind_of( finalize, rb_cProc ) )
  {
    rb_raise( rb_eArgError, "finalize must be a proc" );
  }

  /* FIXME: will the GC kill this before it is used? */
  data = rb_ary_new3( 2, step, finalize );

  result = sqlite_create_aggregate( handle,
              StringValueCStr(name),
              FIX2INT(n),
              static_function_callback,
              static_aggregate_finalize_callback,
              (void*)data );

  if( result != SQLITE_OK )
  {
    static_raise_db_error( result, "create aggregate %s(%d)",
      StringValueCStr(name), FIX2INT(n) );
    /* "raise" does not return */
  }

  return Qnil;
}

create_function( db, name, args, proc ) → nil click to toggle source

Defines a new function that may be invoked from within an SQL statement. The args parameter specifies how many arguments the function expects--use -1 to specify variable arity. The proc parameter must be a proc that expects args + 1 parameters, with the first parameter being an opaque handle to the function object itself:

proc do |func, *args|
  ...
end

The function object is used when calling the set_result and set_result_error methods.

static VALUE
static_api_create_function( VALUE module, VALUE db, VALUE name, VALUE n,
  VALUE proc )
{
  sqlite *handle;
  int     result;

  GetDB( handle, db );
  Check_Type( name, T_STRING );
  Check_Type( n, T_FIXNUM );
  if( !rb_obj_is_kind_of( proc, rb_cProc ) )
  {
    rb_raise( rb_eArgError, "handler must be a proc" );
  }

  result = sqlite_create_function( handle,
              StringValueCStr(name),
              FIX2INT(n),
              static_function_callback,
              (void*)proc );

  if( result != SQLITE_OK )
  {
    static_raise_db_error( result, "create function %s(%d)",
      StringValueCStr(name), FIX2INT(n) );
    /* "raise" does not return */
  }

  return Qnil;
}

finalize( vm ) → nil click to toggle source

Destroys the given virtual machine and releases any associated memory. Once finalized, the VM should not be used.

static VALUE
static_api_finalize( VALUE module, VALUE vm )
{
  sqlite_vm *vm_ptr;
  int        result;
  char      *errmsg;

  /* FIXME: should this be executed atomically? */
  GetVM( vm_ptr, vm );

  result = sqlite_finalize( vm_ptr, &errmsg );
  if( result != SQLITE_OK )
  {
    static_raise_db_error2( result, &errmsg );
    /* "raise" does not return */
  }

  /* don't need to free the handle anymore */
  RDATA(vm)->dfree = NULL;
  RDATA(vm)->data = NULL;

  return Qnil;
}

function_type( db, name, type ) → nil click to toggle source

Allows you to specify the type of the data that the named function returns. If type is SQLite::API::NUMERIC, then the function is expected to return a numeric value. If it is SQLite::API::TEXT, then the function is expected to return a textual value. If it is SQLite::API::ARGS, then the function returns whatever its arguments are. And if it is a positive (or zero) integer, then the function returns whatever type the argument at that position is.

static VALUE
static_api_function_type( VALUE module, VALUE db, VALUE name, VALUE type )
{
  sqlite *handle;
  int     result;

  GetDB( handle, db );
  Check_Type( name, T_STRING );
  Check_Type( type, T_FIXNUM );

  result = sqlite_function_type( handle,
             StringValuePtr( name ),
             FIX2INT( type ) );

  if( result != SQLITE_OK )
  {
    static_raise_db_error( result, "function type %s(%d)",
      StringValuePtr(name), FIX2INT(type) );
    /* "raise" does not return */
  }

  return Qnil;
}

interrupt( db ) → nil click to toggle source

Interrupts the currently executing operation.

static VALUE
static_api_interrupt( VALUE module, VALUE db )
{
  sqlite *handle;

  GetDB( handle, db );
  sqlite_interrupt( handle );

  return Qnil;
}

last_insert_row_id( db ) → fixnum click to toggle source

Returns the unique row ID of the last insert operation.

static VALUE
static_api_last_insert_row_id( VALUE module, VALUE db )
{
  sqlite *handle;

  GetDB( handle, db );

  return INT2FIX( sqlite_last_insert_rowid( handle ) );
}

open( file_name, mode ) → db click to toggle source

Open the named database file. Returns the opaque handle.

static VALUE
static_api_open( VALUE module, VALUE file_name, VALUE mode )
{
  char   *s_file_name;
  char   *errmsg;
  int     i_mode;
  sqlite *db;

  Check_Type( file_name, T_STRING );
  Check_Type( mode,      T_FIXNUM );

  s_file_name = StringValuePtr( file_name );
  i_mode      = FIX2INT( mode );

  db = sqlite_open( s_file_name, i_mode, &errmsg );
  if( db == NULL )
  {
    static_raise_db_error2( -1, &errmsg );
    /* "raise" does not return */
  }

  return Data_Wrap_Struct( rb_cData, NULL, sqlite_close, db );
}

set_result( func, result ) → result click to toggle source

Sets the result of the given function to the given value. This is typically called in the callback function for create_function or the finalize callback in create_aggregate. The result must be either a string, an integer, or a double.

The func parameter must be the opaque function handle as given to the callback functions mentioned above.

static VALUE
static_api_set_result( VALUE module, VALUE func, VALUE result )
{
  sqlite_func *func_ptr;

  GetFunc( func_ptr, func );
  switch( TYPE(result) )
  {
    case T_STRING:
      sqlite_set_result_string( func_ptr,
        RSTRING_PTR(result),
        RSTRING_LEN(result) );
      break;

    case T_FIXNUM:
      sqlite_set_result_int( func_ptr, FIX2INT(result) );
      break;

    case T_FLOAT:
      sqlite_set_result_double( func_ptr, NUM2DBL(result) );
      break;

    default:
      static_raise_db_error( -1, "bad type in set result (%d)",
        TYPE(result) );
  }

  return result;
}

set_result_error( func, string ) → string click to toggle source

Sets the result of the given function to be the error message given in the string parameter. The func parameter must be an opaque function handle as given to the callback function for create_function or create_aggregate.

static VALUE
static_api_set_result_error( VALUE module, VALUE func, VALUE string )
{
  sqlite_func *func_ptr;

  GetFunc( func_ptr, func );
  Check_Type( string, T_STRING );

  sqlite_set_result_error( func_ptr, RSTRING_PTR(string),
    RSTRING_LEN(string) );

  return string;
}

step( vm ) → hash | nil click to toggle source

Steps through a single result for the given virtual machine. Returns a Hash object. If there was a valid row returned, the hash will contain a :row key, which maps to an array of values for that row. In addition, the hash will (nearly) always contain a :columns key (naming the columns in the result) and a :types key (giving the data types for each column).

This will return nil if there was an error previously.

static VALUE
static_api_step( VALUE module, VALUE vm )
{
  sqlite_vm   *vm_ptr;
  const char **values;
  const char **metadata;
  int          columns;
  int          result;
  int          index;
  VALUE        hash;
  VALUE        value;

  GetVM( vm_ptr, vm );
  hash = rb_hash_new();

  result = sqlite_step( vm_ptr,
                        &columns,
                        &values,
                        &metadata );

  switch( result )
  {
    case SQLITE_BUSY:
      static_raise_db_error( result, "busy in step" );

    case SQLITE_ROW:
      value = rb_ary_new2( columns );
      for( index = 0; index < columns; index++ )
      {
        VALUE entry = Qnil;

        if( values[index] != NULL )
          entry = rb_str_new2( values[index] );

        rb_ary_store( value, index, entry  );
      }
      rb_hash_aset( hash, ID2SYM(idRow), value );
      
    case SQLITE_DONE:
      value = rb_ivar_get( vm, idColumns );

      if( value == Qnil )
      {
        value = rb_ary_new2( columns );
        for( index = 0; index < columns; index++ )
        {
          rb_ary_store( value, index, rb_str_new2( metadata[ index ] ) );
        }
        rb_ivar_set( vm, idColumns, value );
      }

      rb_hash_aset( hash, ID2SYM(idColumns), value );

      value = rb_ivar_get( vm, idTypes );

      if( value == Qnil )
      {
        value = rb_ary_new2( columns );
        for( index = 0; index < columns; index++ )
        {
          VALUE item = Qnil;
          if( metadata[ index+columns ] )
            item = rb_str_new2( metadata[ index+columns ] );
          rb_ary_store( value, index, item );
        }
        rb_ivar_set( vm, idTypes, value );
      }

      rb_hash_aset( hash, ID2SYM(idTypes), value );
      break;

    case SQLITE_ERROR:
    case SQLITE_MISUSE:
      {
        char *msg = NULL;
        sqlite_finalize( vm_ptr, &msg );
        RDATA(vm)->dfree = NULL;
        RDATA(vm)->data = NULL;
        static_raise_db_error2( result, &msg );
      }
      /* "raise" doesn't return */

    default:
      static_raise_db_error( -1, "[BUG] unknown result %d from sqlite_step",
        result );
      /* "raise" doesn't return */
  }

  return hash;
}

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