Example 5: desctable

The following example script provides a request procedure which describes the columns of a database table using the AOLserver "ns_tableinfo" command .

This example can be found in the examples/tcl/desctabl.tcl file.

    
    # Example 5: Describing a database table
    #
    # /example/describetable prints out a column-by-column
    #   description of a database table.  The database 
    #   pool name and table name are specified at the end 
    #   of the URL -- e.g.,
    #
    #       /example/describetable/nsdbpool/ns_users
    #
    # Note: You must have the ns_db module loaded into your virtual
    #       server for this example to work.
    #
    # Things to notice:
    #
    # * ns_returnbadrequest returns a nicely formatted message
    #   telling the client they submitted an invalid request.
    #
    # * "ns_conn urlv" returns a Tcl array whose elements are the
    #   slash-delimited parts of the URL.
    #
    # * The describetable function loops through all the columns
    #   and uses "ns_column valuebyindex" to get the type of each
    #   one.
    #
    # * ns_returnnotice nicely formats the return value.
    
    ns_register_proc GET /example/describetable describetable
    
    proc describetable {conn ignore} {
        if {[ns_conn urlc $conn] != 4} {
    	return [ns_returnbadrequest $conn \
    		"Missing table name and/or poolname"]
        }
        set pool [lindex [ns_conn urlv $conn] 2]
        if {[lsearch $pool [ns_db pools]] == -1} {
    	return [ns_returnbadrequest $conn \
    		"Pool $pool does not exist"]
        }
        set db [ns_db gethandle $pool]
        set table [lindex [ns_conn urlv $conn] 3]
        set tinfo [ns_table info $db $table]
        if {$tinfo == ""} {
    	return [ns_returnbadrequest $conn \
    		"Table $table does not exist"]
        }
        set output "<dl>"
        set size [ns_column count $tinfo]
        for {set i 0} {$i < $size} {incr i} {
    	append output "<dt>[ns_column name $tinfo $i] \
                    <dd>[ns_column typebyindex $tinfo $i]</dd>"
        }
        append output "</dl><hr>"
        ns_returnnotice $conn 200 "Table $table in pool $pool" $output
    }
    

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