fix: avoid empty filters

lib/sql.js

@@ -1131,11 +1131,13 @@ SQLConnector.prototype._buildWhere = function(model, where) {
             branches.push(stmtForClause.sql);
           }
         }
-        stmt.merge({
-          sql: '(' + branches.join(' ' + key.toUpperCase() + ' ') + ')',
-          params: branchParams,
-        });
-        whereStmts.push(stmt);
+        if (branches.length > 0) {
+          stmt.merge({
+            sql: '(' + branches.join(' ' + key.toUpperCase() + ' ') + ')',
+            params: branchParams,
+          });
+          whereStmts.push(stmt);
+        }
         continue;
       }
       // The value is not an array, fall back to regular fields

test/sql.test.js

@@ -259,6 +259,47 @@ describe('sql connector', function() {
     expect(where.sql).to.not.match(/ AND $/);
   });
 
+  it('builds where and drops an or with only invalid clauses', function() {
+    const where = connector.buildWhere('customer', {
+      name: 'icecream',
+      or: [{notAColumnName: ''}, {notAColumnNameEither: ''}],
+    });
+    expect(where.toJSON()).to.eql({
+      sql: 'WHERE `NAME`=?',
+      params: ['icecream'],
+    });
+  });
+
+  it('builds empty where for an or with only invalid clauses', function() {
+    const where = connector.buildWhere('customer', {
+      or: [{notAColumnName: ''}, {notAColumnNameEither: ''}],
+    });
+    expect(where.toJSON()).to.eql({
+      sql: '',
+      params: [],
+    });
+  });
+
+  it('builds empty where for an and with only invalid clauses', function() {
+    const where = connector.buildWhere('customer', {
+      and: [{notAColumnName: ''}, {notAColumnNameEither: ''}],
+    });
+    expect(where.toJSON()).to.eql({
+      sql: '',
+      params: [],
+    });
+  });
+
+  it('builds where and drops a nested or with only invalid clauses', function() {
+    const where = connector.buildWhere('customer', {
+      and: [{name: 'John'}, {or: [{notAColumnName: ''}]}],
+    });
+    expect(where.toJSON()).to.eql({
+      sql: 'WHERE ((`NAME`=?))',
+      params: ['John'],
+    });
+  });
+
   it('builds order by with one field', function() {
     const orderBy = connector.buildOrderBy('customer', 'name');
     expect(orderBy).to.eql('ORDER BY `NAME`');