Using COM with PHP(我就不翻譯了)

Using COM with PHP
     By John Lim.

PHP4 on Windows has been extended to support Microsoft's COM technology. However documentation on the COM functions is very sparse at the moment.

Here are some examples of stuff I have tried. Hope this gives you some ideas. Note that these only work when you are running PHP on a Windows Web server.


Active Data Objects (ADO) with PHP
ADO is Microsoft's database object technology. There are objects for connecting to databases, recordsets for data returned from queries, and field objects representing data elements.

Most databases do not support ADO directly. Instead most databases support 2 lower level Microsoft database technologies: ODBC and OLEDB. More databases support ODBC; but OLEDB has a reputation of being faster than ODBC.

ADO is then an API wrapper around ODBC and OLEDB.

This example opens a new ADO Connection object, opens the traditional NorthWind MS-Access database via ODBC. When we execute the SQL, a RecordSet object is returned. We then display the first 3 fields of the record-set.


<?
    $dbc = new COM("ADODB.Connection");
    $dbc->Provider = "MSDASQL";
    $dbc->Open("nwind");
    $rs = $dbc->Execute("select * from products");
    $i = 0;
    $fld0 = $rs->Fields(0);
    $fld1 = $rs->Fields(1);
    $fld2 = $rs->Fields(2);
    while (!$rs->EOF) {
        $i += 1;
        print "$fld0->value $fld1->value $fld2->value<BR>";
        $rs->MoveNext(); /*updates fld0, fld1, fld2 !*/
    }
    $rs->Close();
?>

The equivalent of PHP's print $fld0->value in VBScript is Response.Write( rs.Fields(0).value ); or more concisely Response.Write( rs(0) ) because the default collection of a recordset (rs) is Fields and default property of a Field element is value.

PHP does not support default collections and properties, so we have to write everything explicitly.


Invoking Microsoft Word with PHP
Here is another example.

<?
$word=new COM("word.application") or die("Cannot start MS Word");
print "Loaded word version ($word->Version)\n";
$word->visible = 1 ;
$word->Documents->Add();
$word->Selection->Typetext("This is a test");
?>

Word's COM object model documentation is available in the online help, but it is not in the default installation. Go to the MS Office installer, select VBScript Documentation in options and you will be ready to have some fun!


PHP COM Bugs
While testing ADO, I hit this bug with PHP 4.02. It seems that passing a COM object as a parameter to a second COM object fails.


<?
$dbc = new COM('ADODB.Connection');
$dbc->Provider = 'MSDASQL';
$dbc->Open('NWIND'); // standard sample access database northwind
$rs = new COM("ADODB.Recordset");

/* The following line fails with an INVOKE error */
/* because we are passing $dbc to $rs            */
$rs->Open('select * from product',$dbc,3); // 3 = static cursor
?>

Another bug is that the data types null and currency are not supported.

3 Jan 2001: None of the above bugs have been fixed in PHP 4.0.4. Do we have any COM C++ experts who could fix the bugs? PHP is open source after all.