DataTables

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Introduction

Sahana Eden uses the JavaScript library DataTables ​http://www.datatables.net to display results returned from the database. The DataTables library provides a lot of properties and functions that can customise the table that will be produced. Sahana Eden doesn't expose all of the functionality that is available within the DataTables library this makes it easy to get DataTables up and running and it also ensures a consistent look and feel. However, it is possible to customise the DataTables through the Sahana Eden framework.

The Basics

The Sahana Eden framework will produce a list of resources and put them in a DataTable however sometimes it is necessary to build a table for a specific task or to have multiple tables on the same page. To do this is it necessary to build a controller to manage the table.

Probably the simplest type of table will be one where all the data is sent from the server to the client and no server side pagination is required. This can be set up as follows:

Controller code snippet:

      from s3.s3utils import S3DataTable
      # Set up the resource
      resource = s3db.resource("inv_warehouse")
      # Find out how many records are in the resource
      totalrows = resource.count()
      list_fields = ["id",
                     "name",
                     "organisation_id",
                     ]
      # Get all the data from the resource
      rows = resource.select(list_fields,
                             orderby="organisation_id",
                             start=0,
                             limit=totalrows,
                             )
      if rows:
          # Format the resource data and pass them through their default represent
          data = resource.extract(rows,
                                  list_fields,
                                  represent=True,
                                  )
          # Get the resource fields
          rfields = resource.resolve_selectors(list_fields)[0]
          # Create the default S3DataTable 
          dt = S3DataTable(rfields, data)
          # create default actions buttons for the dataTable
          dt.defaultActionButtons(resource)
          # Create the html for the dataTable
          warehouses = dt.html(totalrows,
                               totalrows,
                               "warehouse_list",
                               dt_pagination="false",
                               )
      else:
          warehouses = "No warehouses exist"

This code gets the rows from the resource and passes the data into the S3DataTable html() function the extra parameter of note is the dt_pagination which when set to 'false' will turn server side pagination off. All the data will be sent to the client and DataTables will manage the filtering a sorting itself.

The next stage is to build a controller that can manage pagination. To do this the controller will need to additionally manage requests from DataTables for more data. This can be set up as follows:

Controller code snippet:

      from s3.s3utils import S3DataTable
      vars = request.get_vars
      resource = s3db.resource("inv_warehouse")
      # When a request is sent from DataTables it sends various information
      # about what data the user has requested, this includes details about
      # records the user wants and any sort or the filter instructions

      # Get the start and end details from dataTables
      start = int(vars.iDisplayStart) if vars.iDisplayStart else 0
      limit = int(vars.iDisplayLength) if vars.iDisplayLength else s3mgr.ROWSPERPAGE
      totalrows = resource.count()
      list_fields = ["id",
                     "name",
                     "organisation_id",
                     ]
      # Get the filter and sort instructions from dataTables
      rfields = resource.resolve_selectors(list_fields)[0]
      (orderby, filter) = S3DataTable.getControlData(rfields, current.request.vars)
      # Now set up the resource filter and find out how many row are in the filtered resource
      resource.add_filter(filter)
      filteredrows = resource.count()
      # Get all the data from the resource
      rows = resource.select(list_fields,
                             orderby="organisation_id",
                             start=start,
                             limit=limit,
                             )
      if rows:
          data = resource.extract(rows,
                                  list_fields,
                                  represent=True,
                                  )
          dt = S3DataTable(rfields, data)
          dt.defaultActionButtons(resource)
          if request.extension == "html":
              # Get the html for the initial call to the dataTable
              warehouses = dt.html(totalrows,
                                   filteredrows,
                                   "warehouse_list",
                                   )
          else:
              # Get any subsequent request for data which will be sent back as json 
              warehouse = dt.json(totalrows,
                                  filteredrows,
                                  "warehouse_list",
                                  int(vars.sEcho),
                                  )
              return warehouse
      else:
          warehouses = "No warehouses exist"

Now the controller needs to manage the two standard request extensions for dataTables: html which is used for the initial table; and aaData which is used for subsequent calls. When the data is prepared for the dataTable it needs to know the total rows in the table and the number of rows that are available after filtering, the filter information is returned from dataTables and the static helper method S3DataTable.getControlData will return the filter and sort information which the user has set up. The json method requires an extra parameter the sEcho which it passes to the server itself. This value just needs to be returned back to the client. Note that the html call now no longer requires the dt_pagination parameter.

Configuring the table

Adding action buttons

The default buttons can be expanded upon by creating a list of buttons to be added to the table. Each button is defined by a dictionary which describes the button. The dictionary can consist of the following items:

Item Name	Description
label	The name that will appear on the button
_class	The class used to display the button, typically use "action-btn" for text and "action-icon" for icons
url	The url which will be used when the button is pressed. Use "[id]" for substituting the id of the record
icon	Optionsal, the icon to be used in place of text

Controller code snippet:

      from s3.s3utils import S3DataTable
      vars = request.get_vars
      resource = s3db.resource("inv_warehouse")
      start = int(vars.iDisplayStart) if vars.iDisplayStart else 0
      limit = int(vars.iDisplayLength) if vars.iDisplayLength else s3mgr.ROWSPERPAGE
      totalrows = resource.count()
      list_fields = ["id",
                     "name",
                     "organisation_id",
                     ]
      rfields = resource.resolve_selectors(list_fields)[0]
      (orderby, filter) = S3DataTable.getControlData(rfields, current.request.vars)
      resource.add_filter(filter)
      filteredrows = resource.count()
      rows = resource.select(list_fields,
                             orderby="organisation_id",
                             start=start,
                             limit=limit,
                             )
      if rows:
          data = resource.extract(rows,
                                  list_fields,
                                  represent=True,
                                  )
          dt = S3DataTable(rfields, data)
          dt.defaultActionButtons(resource)
          if request.extension == "html":
              custom_actions = [dict(label=str(T("Stock")),
                                _class="action-btn",
                                url=URL(c="inv", f="warehouse",
                                        args=["[id]", "inv_item"]
                                        )
                                ),
                               ]
              dt.defaultActionButtons(resource, custom_actions)
              warehouses = dt.html(totalrows,
                                   filteredrows,
                                   "warehouse_list",
                                   )
          else:
              warehouse = dt.json(totalrows,
                                  filteredrows,
                                  "warehouse_list",
                                  int(request.vars.sEcho),
                                  )
              return warehouse
      else:
          warehouses = "No warehouses exist"