improved spreadsheet, issue 860, thanks Alan

VERSION

@@ -1 +1 @@
-Version 2.00.0 (2012-06-25 14:31:49) dev
+Version 2.00.0 (2012-06-25 14:35:08) dev

gluon/contrib/spreadsheet.py

@@ -1,43 +1,21 @@
+# -*- coding: utf-8 -*-
+
 """
 Developed by Massimo Di Pierro, optional component of web2py, GPL2 license.
 """
+
 import re
 import pickle
 import copy
-
+import simplejson
 
 def quote(text):
     return str(text).replace('\\', '\\\\').replace("'", "\\'")
 
 
 class Node:
-    """
-    Example::
-
-         # controller
-         from gluon.contrib.spreadsheet import Sheet
-
-         def callback():
-             return cache.ram('sheet1', lambda: None, None).process(request)
-
-         def index():
-             sheet = cache.ram('sheet1',
-                 lambda: Sheet(10, 10, URL(r=request, f='callback')), 0)
-             #sheet.cell('r0c3', value='=r0c0+r0c1+r0c2', readonly=True)
-             return dict(sheet=sheet)
-
-         # view
-         {{extend 'layout.html'}}
-         {{=sheet}}
-
-         or insert invidivual cells via
-
-         {{=sheet.nodes['r0c0']}}
-
-    """
-
     def __init__(self, name, value, url='.', readonly=False, active=True,
-            onchange=None):
+            onchange=None, **kwarg):
         self.url = url
         self.name = name
         self.value = str(value)
@@ -49,7 +27,7 @@ class Node:
         self.onchange = onchange
         self.size = 4
         self.locked = False
-
+        
     def xml(self):
         return """<input name="%s" id="%s" value="%s" size="%s"
         onkeyup="ajax('%s/keyup',['%s'], ':eval');"
@@ -64,9 +42,192 @@ class Node:
 
 
 class Sheet:
+    """
+    Basic class for creating web spreadsheets
+    
+    New features:
 
-    regex=re.compile('(?<!\w)[a-zA-Z_]\w*')
+    -dal spreadsheets:
+        It receives a Rows object instance and presents
+    the selected data in a cell per field basis (table rows
+    are sheet rows as well)
+    Input should be short extension data as numeric data
+    or math expressions but can be anything supported by
+    unicode.
 
+    -row(), column() and matrix() class methods:
+        These new methods allow to set bulk data sets
+    without calling .cell() for each node
+    Example::
+
+         # controller
+         from gluon.contrib.spreadsheet import Sheet
+
+         def callback():
+             return cache.ram('sheet1', lambda: None, None).process(request)
+
+         def index():
+             # standard spreadsheet method
+             sheet = cache.ram('sheet1',
+                 lambda: Sheet(10, 10, URL(r=request, f='callback')), 0)
+             #sheet.cell('r0c3', value='=r0c0+r0c1+r0c2', readonly=True)
+             return dict(sheet=sheet)
+
+         def index():
+             # database spreadsheet method
+             sheet = cache.ram('sheet1',
+                 lambda: Sheet(10, 10, URL(r=request, f='callback'),
+                 data=db(db.mydata).select()), 0)
+             return dict(sheet=sheet)
+
+         # view
+         {{extend 'layout.html'}}
+         {{=sheet}}
+
+         or insert invidivual cells via
+
+         {{=sheet.nodes['r0c0']}}
+
+    Sheet stores a JavaScript w2p_spreadsheet_data object
+    for retrieving data updates from the client.
+
+    The data structure of the js object is as follows:
+        # columns: a dict with colname, column index map
+        # colnames: a dict with column index, colname map
+        # id_columns: list with id columns
+        # id_colnames: dict with id colname: column index map
+        # cells: dict of "rncn": value pairs
+        # modified: dict of modified cells for client-side
+
+    Also, there is a class method Sheet.update(data) that
+    processes the json data as sent by the client and
+    returns a set of db modifications (see the method help for
+    more details)
+
+    client JavaScript objects:
+    
+    -var w2p_spreadsheet_data
+    Stores cell updates by key and
+    Used for updated cells control
+    
+    -var w2p_spreadsheet_update_button
+    Stores the id of the update command
+    Used for event binding (update click)
+    
+    var w2p_spreadsheet_update_result
+      object attributes:
+        modified - n updated records
+        errors - n errors
+        message - a message for feedback and errors
+        
+    Stores the ajax db update call returned stats
+    and the db_callback string js
+    Used after calling w2p_spreadsheet_update_db()
+    
+    -function w2p_spreadsheet_update_cell(a)
+    Used for responding to normal cell events
+    (encapsulates old behavior)
+    
+    -function w2p_spreadsheet_update_db_callback(result)
+    Called after a background db update
+    
+    -function w2p_spreadsheet_update_db()
+    Called for updating the database with
+    client data
+
+    First method: Sending data trough a form helper:
+    (the data payload must be inserted in a form field before
+    submission)
+
+    -Applying db changes made client-side
+
+    Example controller:
+    ...
+    # present a submit button with the spreadsheet
+    form = SQLFORM.factory(Field("<name>",
+                                 "text",
+                                 readable=False, writable=False,
+                                 formname="<formname>"))
+    # submit button label
+    form.elements("input [type=submit]").attributes["_value"] = \
+    T("Update database")
+    form.elements("textarea")[0].attributes["_style"] = "display: none;"
+
+    w2p_spreadsheet_update_script = SCRIPT('''
+      jQuery(
+        function(){
+          jQuery("<formname>").submit(function(){
+            jQuery("[name=<name>]").val(JSON.stringify(
+              w2p_spreadsheet_data)
+              );
+          });
+        }
+      );
+    ''')
+
+    # retrieve changes
+    if form.process().accepted:
+        data = form.vars.<name>
+        changes = Sheet.updated(data)
+
+        # Do db I/O:
+        for table, rows in changes.iteritems():
+            for row, values in rows.iteritems():
+                db[table][row].update_record(**values)
+
+    # the action view should expose {{=form}}, {{=sheet}}, {{=myscript}}
+    return dict(form=form, sheet=sheet,
+                myscript=w2p_spreadseet_update_script)
+
+    Second method: Sending data updates with .ajax()
+
+    -spreadsheet page's view:
+    
+    {{
+    =INPUT(_type="button", _value="update data",
+             _id="w2p_spreadsheet_update_data")
+    }}
+
+    {{=SCRIPT('''
+    jQuery(function(){
+    jQuery("#w2p_spreadsheet_update_data").click(
+        function(){
+          jQuery.ajax({url: "%s",
+                    type: "POST",
+                    data:
+                      {data:
+                        JSON.stringify(w2p_spreadsheet_data)}
+                    }
+          );
+        }
+    );
+    });
+    ''' % URL(c="default", f="modified"))}}
+
+    -controller: modified function
+    def modified():
+        data = request.vars.data
+        changes = Sheet.updated(data)
+        # (for db I/O see first method)
+        return "ok"
+
+
+    Third method:
+    When creating a Sheet instance, pass a kwarg update_button=<button id>
+    This step will auto process the updated data with db I/O (requires calling
+    .process() with db=<DAL instance>). You must expose an html element which
+    supports the .click() event, i.e. a normal button.
+
+    # TODO:
+    # -¿SIGNED URLS?
+    # -Delete checkbox columns for each table and default
+    # -Deletable=True option for showing/hiding delete checkboxes
+    # -process() method support for db I/O
+    
+    """
+    
+    regex = re.compile('(?<!\w)[a-zA-Z_]\w*')
+    pregex = re.compile('\d+')
     re_strings = re.compile(r'(?P<name>'
                             + r"[uU]?[rR]?'''([^']+|'{1,2}(?!'))*'''|"
                             + r"'([^'\\]|\\.)*'|"
@@ -77,33 +238,180 @@ class Sheet:
         dump = pickle.dumps(self)
         return dump
 
+    @staticmethod
+    def position(key):
+        """ Returns int row, int col for a 'rncn' formatted key'"""
+        try:
+            r, c = Sheet.pregex.findall(key)
+            r, c = int(r), int(c)
+        except (ValueError, IndexError, TypeError), e:
+            error = "%s. %s" % \
+            ("Unexpected position parameter",
+            "Must be a key of type 'rncn'")
+            raise ValueError(error)
+        return r, c
+
     @staticmethod
     def loads(data):
         sheet = pickle.loads(data)
         return sheet
 
-    def process(self, request):
+    @staticmethod
+    def updated(data):
+        """ Reads spreadsheet update information sent client-side.
+
+        Returns a dict with updated database rows/fields.
+        Structure:
+        {<tablename>:{
+                    <id>:{<fieldname>:<new value>,
+                            <fieldname>:<new value>,
+                            ...
+                    },
+                    ...
+                    }
+        }
+
+        data dict argument:
+
+        # columns: (a dict with colname, column index map)
+        # colnames: (a dict with column index, colname map)
+        # id_columns: list with id columns
+        # id_colnames: dict with id colname: column index map
+        # cells: dict of "rncn": value pairs
+        # modified: dict of modified cells for client-side
+
+        """
+        data = simplejson.loads(data)
+
+        # record update dict
+        changes = {}
+
+        # read column index per table
+        # table, id column map
+        tablenames = {}
+        for colname, i in data["id_colnames"].iteritems():
+            tablenames[colname.split(".")[0]] = i
+
+        # Separate multitable rows
+        # Identify each row id (old data)
+        # Build a dict with table/row/field
+        # update information.
+
+        # collect new data by row (modified):
+        for key, value in data["modified"].iteritems():
+            r, c = Sheet.position(key)
+
+            # don't apply repeated values
+            if data["cells"][key] != value:
+                # read tablename
+                tablename, fieldname = data["colnames"][str(c)].split(".")
+
+                # read db record id
+                row_id_key = "r%sc%s" % (r, tablenames[tablename])
+                row_id = data["cells"][row_id_key]
+
+                changes.setdefault(tablename, {})
+                changes[tablename].setdefault(row_id, {})
+                changes[tablename][row_id][fieldname] = value
+
+        return changes
+    
+
+    def process(self, request, db=None, db_callback=None):
         """
         call this in action that creates table, it will handle ajax callbacks
+        optional db (a DAL instance). It's required for db I/O
+        optional callback string. js commands to call after successful
+        ajax db update.
+        db_callback string format keys:
+          modified (number of rows updated)
         """
-        cell = request.vars.keys()[0]
+
-        if request.args(0) == 'focus':
+        if not request.args(0) == "data":
-            return "jQuery('#%s').val('%s');" % (cell, quote(self[cell].value))
+            # normal cell processing
-        value = request.vars[cell]
+            cell = request.vars.keys()[0]
-        self[cell] = value
+
-        if request.args(0) == 'blur':
+            if request.args(0) == 'focus':
-            return "jQuery('#%s').val('%s');" \
+                return "jQuery('#%(cell)s').val('%(value)s');" % \
-                % (cell, quote(self[cell].computed_value))
+                dict(cell=cell, value=quote(self[cell].value))
-        elif request.args(0) == 'keyup':
+
-            jquery = ''
+            value = request.vars[cell]
-            for other_key in self.modified:
+            self[cell] = value
-                if other_key != cell:
+
-                    jquery += "jQuery('#%s').val('%s');" % \
+            if request.args(0) == 'blur':
-                        (other_key, quote(self[other_key].computed_value))
+                return "jQuery('#%(cell)s').val('%(value)s');" % \
+                dict(cell=cell, value=quote(self[cell].computed_value))
+
+            elif request.args(0) == 'keyup':
+                jquery = ''
+                for other_key in self.modified:
+                    if other_key != cell:
+                        jquery += "jQuery('#%(other_key)s').val('%(value)s');" % \
+                        dict(other_key=other_key,
+                            value=quote(self[other_key].computed_value))
+
+        else:
+            # spreadsheet db update
+            result = dict(modified=0,
+                          errors=0,
+                          message="",
+                          db_callback="")
+
+            if db is not None:
+                data = request.vars["data"]
+                changes = self.updated(data)
+
+                # Do db I/O:
+                for table, rows in changes.iteritems():
+                    for row, values in rows.iteritems():
+                        db[table][row].update_record(**values)
+                        result["modified"] += 1
+
+                if db_callback is not None:
+                    result["db_callback"] = db_callback
+            else:
+                result["message"] = "Sheet.process Error. No db found."
+            return simplejson.dumps(result)
+
         return jquery
 
-    def __init__(self, rows, cols, url='.', readonly=False, active=True,
+    def get_attributes(self, data):
-            onchange=None):
+        attributes = {}
+        for k in data.keys():
+            if k.startswith("_"):
+                attributes[k] = data[k]
+        return attributes
+
+    def even_or_odd(self, v):
+        """ Used for table row stripping """
+        if v % 2 == 0:
+            return "even"
+        else:
+            return "odd"
+
+    def __init__(self, rows, cols, url='.', readonly=False,
+            active=True, onchange=None, value=None, data=None,
+            headers=None, update_button="", **kwarg):
+
+        """
+        Arguments:
+        headers: a dict with "table.fieldname": name values
+        value: common value for all spreadsheet
+        (can be a lambda x, y: z or function reference)
+
+        Rows and cols values will be updated automatically to fit
+        the data boundaries when the data argument is a Rows object.
+
+        self.client: for storing sheet data client side
+        columns: a dict with colname, column index map
+        colnames: a dict with column index, colname map
+        id_columns: list with id columns
+        id_colnames: dict with id colname: column index map
+        cells: dict of "rncn": value pairs
+        modified: dict of modified cells for client-side
+        edition.
+        """
+
         self.rows = rows
         self.cols = cols
         self.url = url
@@ -111,9 +419,74 @@ class Sheet:
         self.error = 'ERROR: %(error)s'
         self.allowed_keywords = ['for', 'in', 'if', 'else', 'and', 'or', 'not',
                                'i', 'j', 'k', 'x', 'y', 'z', 'sum']
+        self.value = value
         self.environment = {}
-        [self.cell('r%sc%s'%(k/cols, k%cols), '0.0', readonly, active, onchange)
+        self.attributes = self.get_attributes(kwarg)
-            for k in xrange(rows*cols)]
+        self.tr_attributes = {}
+        self.td_attributes = {}
+
+        self.data = data
+        self.readonly = readonly
+
+        self.update_button = update_button
+        
+        self.client = {
+                        "columns": {},
+                        "colnames": {},
+                        "id_columns": [],
+                        "id_colnames": {},
+                        "cells": {},
+                        "modified": {},
+                        "headers": headers
+                        }
+                        
+        # if db and query:
+        if self.data is not None:
+            # retrieve row columns length
+            self.rows = len(self.data)
+            # retrieve rows length
+            self.cols = len(self.data.colnames)
+            
+            # map row data to rncn values
+            for x, colname in enumerate(self.data.colnames):
+                self.client["columns"][colname] = x
+                self.client["colnames"][x] = colname
+
+            for x, row in enumerate(self.data):
+                for colname, y in self.client["columns"].iteritems():
+                    key = "r%sc%s" % (x, y)
+                    tablename, fieldname = colname.split(".")
+                    try:
+                        value = row[tablename][fieldname]
+                    except (KeyError, AttributeError):
+                        # single table query
+                        value = row[fieldname]
+                    self.client["cells"][key] = str(value)
+                    # TODO: support different id keys
+                    if ".id" in colname:
+                        self.client["id_columns"].append(y)
+                        self.client["id_colnames"][colname] = y
+
+        for k in xrange(self.rows*self.cols):
+            key = 'r%sc%s'%(k/self.cols, k%self.cols)
+            r, c = self.position(key)
+            if self.client["cells"].has_key(key):
+                value = self.client["cells"][key]
+                # readonly id values
+                if c in self.client["id_columns"]:
+                    readonly = True
+                else:
+                    readonly = self.readonly
+            elif self.value is not None:
+                if callable(self.value):
+                    value = self.value(r, c)
+                else:
+                    value = self.value
+            else:
+                value = '0.00'
+            self.cell(key, value,
+                    readonly, active, onchange)
+
         exec('from math import *', {}, self.environment)
 
     def delete_from(self, other_list):
@@ -131,19 +504,179 @@ class Sheet:
     def define(self, name, obj):
         self.environment[name] = obj
 
-    def cell(self, key, value, readonly=False, active=True, onchange=None):
+    def cell(self, key, value, readonly=False, active=True,
+             onchange=None, **kwarg):
         """
         key is the name of the cell
         value is the initial value of the cell. It can be a formula "=1+3"
-        a cell is active if it evaluates formuls
+        a cell is active if it evaluates formulas
+
+        Value can be a function(r, c) which returns a string
         """
-        key = str(key)
+
         if not self.regex.match(key):
             raise SyntaxError, "Invalid cell name: %s" % key
-        node = Node(key, value, self.url, readonly, active, onchange)
+        else:
+            attributes = self.get_attributes(kwarg)
+            if attributes is not None:
+                self.td_attributes[key] = attributes
+
+        key = str(key)
+        r, c = self.position(key)
+
+        if callable(value):
+            value = value(r, c)
+
+        node = Node(key, value, self.url, readonly, active,
+                    onchange, **kwarg)
         self.nodes[key] = node
         self[key] = value
 
+    def get_cell_arguments(self, data, default=None):
+        """Reads cell arguments from a dict object"""
+        active = True
+        onchange = None
+        readonly = False
+        value = ""
+        if default is not None:
+            data.update(default)
+        if "active" in data:
+            active = data["active"]
+        if "readonly" in data:
+            readonly = data["readonly"]
+        if "onchange" in data:
+            onchange = data["onchange"]
+        if "value" in data:
+            value = data["value"]
+        return active, onchange, readonly, value
+
+    def row(self, row, cells, value=None, **kwarg):
+        # row: row index (0, 1, ...)
+        # cells: a sequence of values or a dict of dict with
+        # arg: value pairs
+        # one column example:
+        # {"0": {"value":1.0, "readonly":False, "active":True, "onchange":None}}
+        # value: common value for all cells
+        
+        attributes = self.get_attributes(kwarg)
+        if attributes is not None:
+            self.tr_attributes[str(row)] = attributes
+        if isinstance(cells, dict):
+            for col, data in cells.iteritems():
+                key = "r%sc%s" % (row, col)
+                active, onchange, readonly, cell_value = \
+                self.get_cell_arguments(data, default=kwarg)
+                if value is None:
+                    v = cell_value
+                else:
+                    v = value
+                self.cell(key, v, active=active,
+                          readonly=readonly,
+                          onchange=onchange, **attributes)
+        else:
+            active, onchange, readonly, all_value = \
+            self.get_cell_arguments(kwarg)
+            for col, cell_value in enumerate(cells):
+                key = "r%sc%s" % (row, col)
+                if value is None:
+                    v = cell_value
+                else:
+                    v = value
+                self.cell(key, v, active=active,
+                          onchange=onchange,
+                          readonly=readonly, **attributes)
+
+    def column(self, col, cells, value=None, **kwarg):
+        """
+        # col: column index (0, 1, ...)
+        # cells: a sequence of values or a dict of dict with
+        # arg: value pairs
+        # one row example:
+        # {"0": {"value":1.0, "readonly":False, "active":True, "onchange":None}}
+        # value: common value for all cells        
+        """
+        attributes = self.get_attributes(kwarg)
+        
+        if isinstance(cells, dict):
+            for row, data in cells.iteritems():
+                key = "r%sc%s" % (row, col)
+                active, onchange, readonly, cell_value = \
+                self.get_cell_arguments(data, default=kwarg)
+                if value is None:
+                    v = cell_value
+                else:
+                    v = value
+                self.cell(key, v, active=active, readonly=readonly,
+                          onchange=onchange, **attributes)
+        else:
+            active, onchange, readonly, all_value = \
+            self.get_cell_arguments(kwarg) 
+            for row, cell_value in enumerate(cells):
+                key = "r%sc%s" % (row, col)
+                if value is None:
+                    v = cell_value
+                else:
+                    v = value
+                self.cell(key, v, active=active,
+                          onchange=onchange, readonly=readonly,
+                          **attributes)
+
+    def matrix(self, cells, starts="r0c0", ends=None, value=None, **kwarg):
+        """
+        Insert a n x n matrix or a set of cells
+        # starts: upper left cell
+        # ends: lower right cell
+        
+        # cells: a sequence of value sequences
+        # or a dict with "rncn" keys
+        # Example 1 cells:
+        # ((v11, v12, ... v1n),
+           (vn2, vn2, ... vnn))
+        # Example 2 cells:
+        # {"r0c0": {...}, ... "rncn": {...}}
+        # value: common value for all cells
+        """
+        attributes = self.get_attributes(kwarg)
+        
+        starts_r, starts_c = self.position(starts)
+        ends_r, ends_c = None, None
+        if ends is not None:
+            ends_r, ends_c = self.position(ends)
+
+        if isinstance(cells, dict):
+            for key, data in cells.iteritems():
+                r, c = self.position(key)
+                key = "r%sc%s" % (r+starts_r, c+starts_c)
+                active, onchange, readonly, cell_value = \
+                self.get_cell_arguments(data, default=kwarg)
+                if value is None:
+                    v = cell_value
+                else:
+                    v = value
+                if (ends is None) or ((ends_r >= r+starts_r) and\
+                                      (ends_c >= c+starts_c)):
+                    self.cell(key, v, active=active,
+                            readonly=readonly,
+                            onchange=onchange, **attributes)
+        else:
+            active, onchange, readonly, all_value = \
+            self.get_cell_arguments(kwarg)
+            for r, row in enumerate(cells):
+                for c, cell_value in enumerate(row):
+                    if value is None:
+                        v = cell_value
+                    else:
+                        v = value
+                    key = "r%sc%s" % (r+starts_r, c+starts_c)
+                    if (ends is None) or \
+                       ((ends_r >= r+starts_r) and\
+                        (ends_c >= c+starts_c)):
+                        self.cell(key, v,
+                                active=active,
+                                onchange=onchange,
+                                readonly=readonly,
+                                **attributes)
+
     def __setitem__(self, key, value):
         key = str(key)
         value = str(value)
@@ -240,19 +773,103 @@ class Sheet:
             if node.value[:1] != '=' or not node.active:
                 node.value = d[key]
 
-    def xml(self):
+    def sheet(self):
         import gluon.html
-        (DIV, TABLE, TR, TD, TH, BR) = \
+        (DIV, TABLE, TR, TD, TH, BR, SCRIPT) = \
             (gluon.html.DIV, gluon.html.TABLE, gluon.html.TR, gluon.html.TD,
-             gluon.html.TH, gluon.html.BR)
+             gluon.html.TH, gluon.html.BR, gluon.html.SCRIPT)
         regex = re.compile('r\d+c\d+')
-        return DIV(TABLE(TR(TH(), *[TH('c%s' % c) for c in range(self.cols)]),
+
-                         *[TR(TH('r%s' % r), *[TD(self.nodes['r%sc%s'%(r, c)]) \
+        header = TR(TH(), *[TH('c%s' % c) \
-                                                  for c in range(self.cols)]) \
+                          for c in range(self.cols)])
-                                                    for r in range(self.rows)]),
+        rows = []
+        for r in range(self.rows):
+            tds = [TH('r%s' % r),]
+            for c in range(self.cols):
+                key = 'r%sc%s'%(r, c)
+                attributes = {"_class": "w2p_spreadsheet_col_%s" % \
+                self.even_or_odd(c)}
+                if key in self.td_attributes:
+                    attributes.update(self.td_attributes[key])
+                td = TD(self.nodes[key], **attributes)
+                tds.append(td)
+            attributes = {"_class": "w2p_spreadsheet_row_%s" % \
+            self.even_or_odd(r)}
+            if str(r) in self.tr_attributes:
+                attributes.update(self.tr_attributes[str(r)])
+            rows.append(TR(*tds, **attributes))
+
+        attributes = {"_class": "w2p_spreadsheet"}
+        attributes.update(self.attributes)
+
+        table = TABLE(header, *rows, **self.attributes)
+
+        if len(self.client["cells"]) >= 1:
+            data = SCRIPT(\
+            """
+            var w2p_spreadsheet_data = %(data)s;
+            var w2p_spreadsheet_update_button = "%(update_button)s";
+            var w2p_spreadsheet_update_result = null;
+            function w2p_spreadsheet_update_cell(a){
+              // update data
+              w2p_spreadsheet_data.modified[this.id] = this.value;
+            }
+            function w2p_spreadsheet_update_db_callback(result){
+              w2p_spreadsheet_update_result = result;
+              eval(w2p_spreadsheet_update_result.db_callback);
+            }
+            function w2p_spreadsheet_update_db(){
+              // ajax background db update
+              jQuery.ajax({url: "%(url)s/data",
+                           type: "POST",
+                           data:
+                             {data: JSON.stringify(w2p_spreadsheet_data)},
+                           dataType: "json",
+                           success: w2p_spreadsheet_update_db_callback
+                           });
+            }
+            // add onchange cell update event
+            jQuery(function(){
+              jQuery(".%(name)s input").change(w2p_spreadsheet_update_cell);
+            });
+            
+            if (w2p_spreadsheet_update_button != ""){
+              jQuery(function(){
+                jQuery("#" + w2p_spreadsheet_update_button).click(w2p_spreadsheet_update_db);
+              });
+            }
+            """ % dict(data=simplejson.dumps(self.client),
+                       name=attributes["_class"],
+                       url=self.url,
+                       update_button=self.update_button))
+
+            # extra row for fieldnames
+            unsorted_headers = []
+            if self.client["headers"] is not None:
+                for fieldname, name in self.client["headers"].iteritems():
+                    unsorted_headers.append((self.client["columns"][fieldname],
+                                         name))
+            else:
+                for fieldname, c in self.client["columns"].iteritems():
+                    unsorted_headers.append((c, fieldname))
+
+            sorted_headers = [TH(),] + \
+            [TH(header[1]) for header in sorted(unsorted_headers)]
+            table.insert(0, TR(*sorted_headers, _class="%s_fieldnames" % \
+                               attributes["_class"]))
+
+        else:
+            data = SCRIPT(""" // web2py Spreadsheets: no db data.""")
+
+        return DIV(table,
                    BR(),
                    TABLE(*[TR(TH(key), TD(self.nodes[key])) \
-                       for key in self.nodes if not regex.match(key)])).xml()
+                           for key in self.nodes if not regex.match(key)]),
+                   data, **attributes)
+
+    def xml(self):
+        return self.sheet().xml()
+
 
 if __name__ == '__main__':
     s = Sheet(0, 0)
@@ -261,7 +878,3 @@ if __name__ == '__main__':
     s.cell('c', value="=cos(a)**2+b*b")
     print s['c'].computed_value
 
-
-
-
-