Re: Call for review: Database API for the GNADE Project

[Michael Erdmann <michael.erdmann@snafu.de>]

Since the GNADE projects  objective is to be also
a repository for different approaches to Ada 95
data base interfaces for Ada 95 it is very  usefull.
Please could you send me a copy, or even better
if you like we can present it on the  project pages
if you are willing to support the code in the future
as a member of the GNADE team?

Michael


Julio Cano schrieb:

> This is what I did time ago. It's not finished nor completed but it
> works for little examples. The first version was made in C to access
> PostgresQL so y called it "pgrecordset", but the table it returns is
> not dynamc (can't be modified).
> Actualy is in Ada and uses GNADE odbc.
> It may look like MS DAO too, but if it's usefull....
> The main ads is:
>
> ---------------------
> with Ada.Strings.Unbounded;
> use Ada.Strings.Unbounded;
>
> with Data_Bind;
> use Data_Bind;
>
> generic
>    Conninfo : String;
>    Username : String := "";
>    Passwd : String := "";
> package PGRecordset is
>
>    type Pgrecordset_ptr is private;
> --   type String_Access is access all String;
>
>    NO_DATA : exception;
>    DATABASE_ERROR : exception;
>
>    function Get_Bind_List (Recordset : Pgrecordset_Ptr) return
> Base_Data;
>    procedure Set_Bind_List (Recordset : in out Pgrecordset_Ptr; List :
> Base_Data);
>
>    procedure Registerdata (Recordset: Pgrecordset_Ptr; Str:
> String_Access; Field : String);
>
>    function First_Field (Recordset : Pgrecordset_Ptr) return Integer;
>    function Last_Field (Recordset : Pgrecordset_Ptr) return Integer;
>
>    procedure MoveFirst (Recordset : Pgrecordset_Ptr);
>    procedure MoveNext (Recordset : Pgrecordset_Ptr);
>
>    function Recordset_New(Conninfo : String; Username : String := "";
> Passwd : String := "") return Pgrecordset_ptr;
>    procedure recordset_Close(recordset : in out Pgrecordset_Ptr);
>    -- Theese handle new connexions
>
>    function Recordset_New return Pgrecordset_ptr;
>    procedure recordset_Close;
>    -- Theese handle default conx. so that new conx. doesn't have to be
> created.
>
>    function error (Recordset : Pgrecordset_Ptr) return Boolean;
>    -- Returns true if there was an error.
>
>    function Error_Msg (Recordset : Pgrecordset_ptr) return String;
>    -- Returns a string explaining the error.
>
>    procedure error_Msg (Recordset : Pgrecordset_Ptr; Msg : out
> String);
>    -- Sets Msg with the error string;
>
>    procedure query (Recordset : in out Pgrecordset_Ptr; Query :
> String);
>    -- Sends the query to de database and returns the resulting table;
>
>    procedure Exec (Recordset : in out Pgrecordset_Ptr; Cmd : String);
>    -- Sends the command to the database but returns no result.
>
>    function Getcolnums (Rs: Pgrecordset_Ptr) return Integer;
>    -- Returns number of columns in query table.
>
>    function Getcolname (Rs: Pgrecordset_Ptr; Num: integer) return
> String;
>    -- Returns the column name.
>
>    function GetData (Rs: Pgrecordset_Ptr; Column : String) return
> String;
>    -- Returns data in the named column in actual register.
>
> private
>
>    type Pgrecordset;
>    type Pgrecordset_Ptr is access all pgRecordset;
>
>    procedure check_errors (conx : in out pgrecordset_ptr);
> end PGRecordset;
> ---------------------
>
> Data Binding....
> -------------------
>
> with Gnu.Db.Sqlcli;
> use Gnu.Db.Sqlcli;
> with Gnu.Db.Sqlcli.Bind;
>
> with Ada.Strings.Unbounded;
> use Ada.Strings.Unbounded;
>
> package Data_Bind is
>
>    type Data_List is tagged private;
>    type Base_Data is private;
>    procedure DataFix (Elem : access Data_List);
>    procedure Binddata (Data : access Data_List; Stmt : Sqlhstmt);
>
>    type String_Data is private;
>    type String_Data_Ptr is private;
>    procedure DataFix (Elem : access String_Data);
>    procedure Binddata (Data : access String_Data; Stmt : Sqlhstmt);
>
>    -- This limits string data lenght to 256!!!!!
>    subtype sql_str is String(1..256);
>    type sql_str_access is access all sql_str;
>
>    function Name2col (Stmt   : Sqlhstmt; Column : Unbounded_String )
> return Sql_Column_Number;
>
> --   procedure DataListFix ( List : access Data_List'Class);
>    procedure DataListFix ( List : Base_Data);
>
>    procedure RegisterData (List : in out Base_Data; Data :
> String_access; Column : String);
>
>    procedure UnRegisterData (List : in out Base_Data; Column :
> String);
>
>    procedure UnRegisterAll (List : in out Base_Data);
>
>    procedure Binddatalist (List : Base_Data; Stmt : Sqlhstmt);
>
> private
>
>    type Base_Data is access all Data_List'Class;
>    type Data_List is tagged
>       record
>          Field : Unbounded_String;
>          Next  : Base_Data;
>       end record;
>
>    package String_Binding is new Gnu.Db.Sqlcli.Bind (Sql_Str,
>                                                      Sql_Str_Access);
>    package Sb renames String_Binding;
>
>    type String_Data is new Data_List with
>       record
>          Data        : String_access;
>          Data_Length : aliased Sqlinteger;
>          Binded : Sql_Str_Access;
>       end record;
>    type String_Data_Ptr is access all String_Data;
>
> end Data_Bind;
> -------------------------
> Extending this data_bind package should let you bind another data
> types.
> I tried to make this a pgrecordset's child package but i didnt find
> the way...
>
> The next one is an example using the this package. Sorry for the
> variable names in spanish... ;)
> ----------------
>
> with Pgrecordset;
> with Data_Bind;
> with text_io;
>
> procedure Lista4 is
>    package Db renames Pgrecordset;
>
>    Conx : Db.Pgrecordset_Ptr;
>
>    nombre : aliased String(1..30);
>    Direc : aliased String (1..40);
>    Edad : aliased String(1..5);
>
>    Edad2 : Integer;
> begin
>
>    Conx := Db.Recordset_New("gestion");
>
>    db.registerdata (Conx, nombre'Unrestricted_access, "name");
>    db.registerdata (Conx, direc'Unrestricted_access, "address");
>    db.registerdata (Conx, edad'Unrestricted_access, "age");
>    db.query (conx, "select * from customers");
>    db.movefirst(conx);
>
>    declare
>       fin : boolean := false;
>    begin
>       loop
>          text_io.put_line ("Nombre : " & nombre);
>          text_io.put_line ("Direc : " & direc);
>          text_io.put_line ("edad : " & edad);
>          db.movenext(conx);
>          exit when Fin;
>       end loop;
>    exception
>       when db.no_data => fin := true;
>       when others => text_io.put_line ("Exception no tratada.");
>    end;
>
> --   Edad2 := integer'value(Edad) + 10;
> --   Db.Exec (Conx, "insert into customers values
> ('"&Nombre&"','"&direc&"','"&Integer'Image(Edad2)&"')");
>
>    declare begin
>       Db.Recordset_Close (Conx);
>       exception when others => Text_Io.Put_Line ("!!!!!!!");
>       end;
>
> end Lista4;
> ----------------
> Hope this is usefull. I could send it to anybody...
>
> Bye.