Drupal - what is the hook to preprocess a view?

You can use something along the lines of this:

MYMODULE_views_pre_render(&$view) {

  if ($view->name=='NAMEOFTHEVIEW') {

    foreach($view->result as $r => $result) {
      // do whatever you want with each "row"
    }

  }

  // other views might go here

}

and this is certainly NOT a bad practice at all, and, at least IMHO, far superior to php fields in the view itself.

So by design, every single theme hook defined by hook_theme will have a preprocess function called for it. The trick with Views is knowing what all of those actually are.

To get the definition of every Views theme hook available for your current site, you'll need drush, but you can do the following:

drush @alias php-eval "var_dump(array_keys(views_theme()));"

That will spit back every theme hook defined for Views on the current site. For me it returned the following:

array(35) {
  [0] =>
  string(16) "views_mini_pager"
  [1] =>
  string(16) "views_view_field"
  [2] =>
  string(19) "views_view_grouping"
  [3] =>
  string(10) "views_view"
  [4] =>
  string(22) "views_view_unformatted"
  [5] =>
  string(17) "views_data_export"
  [6] =>
  string(28) "views_data_export_csv_header"
  [7] =>
  string(26) "views_data_export_csv_body"
  [8] =>
  string(28) "views_data_export_csv_footer"
  [9] =>
  string(28) "views_data_export_doc_header"
  [10] =>
  string(26) "views_data_export_doc_body"
  [11] =>
  string(28) "views_data_export_doc_footer"
  [12] =>
  string(28) "views_data_export_txt_header"
  [13] =>
  string(26) "views_data_export_txt_body"
  [14] =>
  string(28) "views_data_export_txt_footer"
  [15] =>
  string(28) "views_data_export_xls_header"
  [16] =>
  string(26) "views_data_export_xls_body"
  [17] =>
  string(28) "views_data_export_xls_footer"
  [18] =>
  string(28) "views_data_export_xml_header"
  [19] =>
  string(26) "views_data_export_xml_body"
  [20] =>
  string(28) "views_data_export_xml_footer"
  [21] =>
  string(14) "views_view_raw"
  [22] =>
  string(15) "views_view_list"
  [23] =>
  string(15) "views_view_grid"
  [24] =>
  string(16) "views_view_table"
  [25] =>
  string(18) "views_view_summary"
  [26] =>
  string(30) "views_view_summary_unformatted"
  [27] =>
  string(14) "views_view_rss"
  [28] =>
  string(28) "views_view_summary_jump_menu"
  [29] =>
  string(20) "views_view_jump_menu"
  [30] =>
  string(17) "views_view_fields"
  [31] =>
  string(18) "views_view_row_rss"
  [32] =>
  string(21) "views_form_views_form"
  [33] =>
  string(18) "views_exposed_form"
  [34] =>
  string(10) "views_more"
}

So, in my case, I needed to add some additional row data to views_data_export_xml_body. So I defined the following in my module:

function my_module_preprocess_views_data_export_xml_body(&$vars) {
  $vars['themed_rows'][0]['item_1'] = 'whatever';
}

It's not a very practical example but it does demonstrate how to discover, identify, and implement a preprocess function for any Views theme hook. Hope this helps.

I like this page : The life of a view

Views is an amazing module not only because of its UI for query generating but also as it provides comprehensive hooks.

Sometimes these hooks confuse beginners with their sequence.

Here is the processing sequence of these hooks for your convenience.