Remove != '' filter from queries

This effectively reverts dc7d8d0 (changes were moved to different files,
so it is more transparent to do this in a new commit).

Fixes issues with negative filters #358 #380 #656

TODO: Correct filtering on prefixed/postfixed fields, like the original commit was supposed to do, but without side effects that break normal non-prefixed fields.

Author: annda

_test/types/TextTest.php

@@ -24,31 +24,31 @@ public function data()
                 '', // postfix
                 '=', // comp
                 'val', // value
-                '((T.col != \'\' AND T.col = ?))', // expect sql
+                '(T.col = ?)', // expect sql
                 ['val'], // expect opts
             ],
             [
                 'before', // prefix
                 '', // postfix
                 '=', // comp
                 'val', // value
-                '((T.col != \'\' AND ? || T.col = ?))', // expect sql
+                '(? || T.col = ?)', // expect sql
                 ['before', 'val'], // expect opts
             ],
             [
                 '', // prefix
                 'after', // postfix
                 '=', // comp
                 'val', // value
-                '((T.col != \'\' AND T.col || ? = ?))', // expect sql
+                '(T.col || ? = ?)', // expect sql
                 ['after', 'val'], // expect opts
             ],
             [
                 'before', // prefix
                 'after', // postfix
                 '=', // comp
                 'val', // value
-                '((T.col != \'\' AND ? || T.col || ? = ?))', // expect sql
+                '(? || T.col || ? = ?)', // expect sql
                 ['before', 'after', 'val'], // expect opts
             ],
             // LIKE
@@ -57,31 +57,31 @@ public function data()
                 '', // postfix
                 'LIKE', // comp
                 '%val%', // value
-                '((T.col != \'\' AND T.col LIKE ?))', // expect sql
+                '(T.col LIKE ?)', // expect sql
                 ['%val%'], // expect opts
             ],
             [
                 'before', // prefix
                 '', // postfix
                 'LIKE', // comp
                 '%val%', // value
-                '((T.col != \'\' AND ? || T.col LIKE ?))', // expect sql
+                '(? || T.col LIKE ?)', // expect sql
                 ['before', '%val%'], // expect opts
             ],
             [
                 '', // prefix
                 'after', // postfix
                 'LIKE', // comp
                 '%val%', // value
-                '((T.col != \'\' AND T.col || ? LIKE ?))', // expect sql
+                '(T.col || ? LIKE ?)', // expect sql
                 ['after', '%val%'], // expect opts
             ],
             [
                 'before', // prefix
                 'after', // postfix
                 'LIKE', // comp
                 '%val%', // value
-                '((T.col != \'\' AND ? || T.col || ? LIKE ?))', // expect sql
+                '(? || T.col || ? LIKE ?)', // expect sql
                 ['before', 'after', '%val%'], // expect opts
             ],
             // NOT LIKE
@@ -90,31 +90,31 @@ public function data()
                 '', // postfix
                 'NOT LIKE', // comp
                 '%val%', // value
-                '((T.col != \'\' AND T.col NOT LIKE ?))', // expect sql
+                '(T.col NOT LIKE ?)', // expect sql
                 ['%val%'], // expect opts
             ],
             [
                 'before', // prefix
                 '', // postfix
                 'NOT LIKE', // comp
                 '%val%', // value
-                '((T.col != \'\' AND ? || T.col NOT LIKE ?))', // expect sql
+                '(? || T.col NOT LIKE ?)', // expect sql
                 ['before', '%val%'], // expect opts
             ],
             [
                 '', // prefix
                 'after', // postfix
                 'NOT LIKE', // comp
                 '%val%', // value
-                '((T.col != \'\' AND T.col || ? NOT LIKE ?))', // expect sql
+                '(T.col || ? NOT LIKE ?)', // expect sql
                 ['after', '%val%'], // expect opts
             ],
             [
                 'before', // prefix
                 'after', // postfix
                 'NOT LIKE', // comp
                 '%val%', // value
-                '((T.col != \'\' AND ? || T.col || ? NOT LIKE ?))', // expect sql
+                '(? || T.col || ? NOT LIKE ?)', // expect sql
                 ['before', 'after', '%val%'], // expect opts
             ],
 
@@ -124,7 +124,7 @@ public function data()
                 'after', // postfix
                 'NOT LIKE', // comp
                 ['%val1%', '%val2%'], // multiple values
-                '((T.col != \'\' AND (? || T.col || ? NOT LIKE ? OR ? || T.col || ? NOT LIKE ?)))', // expect sql
+                '((? || T.col || ? NOT LIKE ? OR ? || T.col || ? NOT LIKE ?))', // expect sql
                 ['before', 'after', '%val1%', 'before', 'after', '%val2%',], // expect opts
             ],
         ];

types/TraitFilterPrefix.php

@@ -26,11 +26,6 @@ trait TraitFilterPrefix
      */
     public function filter(QueryBuilderWhere $add, $tablealias, $colname, $comp, $value, $op)
     {
-        $add = $add->where($op); // open a subgroup
-        $add->where('AND', "$tablealias.$colname != ''");
-         // make sure the field isn't empty
-        $op = 'AND';
-
         /** @var QueryBuilderWhere $add Where additionional queries are added to */
         if (is_array($value)) {
             $add = $add->where($op); // sub where group