From e52cdf4b935f0beabe559a2920dd7fcb768707be Mon Sep 17 00:00:00 2001
From: Tony Pitale <tpitale@gmail.com>
Date: Tue, 24 May 2016 01:25:09 -0500
Subject: [PATCH 1/2] Raise error in Repository#read if query is not valid;
 resolve #16

---
 lib/dm-core/query.rb      | 2 ++
 lib/dm-core/repository.rb | 2 +-
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/lib/dm-core/query.rb b/lib/dm-core/query.rb
index b47fd3e7d..c41cfed87 100644
--- a/lib/dm-core/query.rb
+++ b/lib/dm-core/query.rb
@@ -29,6 +29,8 @@ class Query
     include DataMapper::Assertions
     extend Equalizer
 
+    InvalidConditionsError = Class.new(StandardError)
+
     OPTIONS = [ :fields, :links, :conditions, :offset, :limit, :order, :unique, :add_reversed, :reload ].to_set.freeze
 
     equalize :repository, :model, :sorted_fields, :links, :conditions, :order, :offset, :limit, :reload?, :unique?, :add_reversed?
diff --git a/lib/dm-core/repository.rb b/lib/dm-core/repository.rb
index 66324ec4b..7de061d77 100644
--- a/lib/dm-core/repository.rb
+++ b/lib/dm-core/repository.rb
@@ -158,7 +158,7 @@ def create(resources)
     #
     # @api semipublic
     def read(query)
-      return [] unless query.valid?
+      raise InvalidConditionsError unless query.valid?
       query.model.load(adapter.read(query), query)
     end
 

From a6afe3e8e9879ebacebc68c05f0f32b16b4ee4cb Mon Sep 17 00:00:00 2001
From: Tony Pitale <tpitale@gmail.com>
Date: Thu, 26 May 2016 15:36:53 -0500
Subject: [PATCH 2/2] Rescue invalid query in collection and model to maintain
 outward functionality; may be a bad idea

---
 lib/dm-core/collection.rb |  6 +++++-
 lib/dm-core/model.rb      | 12 ++++++++++--
 lib/dm-core/repository.rb |  2 +-
 3 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/lib/dm-core/collection.rb b/lib/dm-core/collection.rb
index ad3886221..50870d781 100644
--- a/lib/dm-core/collection.rb
+++ b/lib/dm-core/collection.rb
@@ -1116,7 +1116,11 @@ def lazy_load
       tail  = self.tail
       query = self.query
 
-      resources = repository.read(query)
+      resources = begin
+        repository.read(query)
+      rescue Query::InvalidConditionsError
+        []
+      end
 
       # remove already known results
       resources -= head          if head.any?
diff --git a/lib/dm-core/model.rb b/lib/dm-core/model.rb
index f206873dc..01a06f8df 100644
--- a/lib/dm-core/model.rb
+++ b/lib/dm-core/model.rb
@@ -380,7 +380,11 @@ def first(*args)
       if limit_specified
         all(query)
       else
-        query.repository.read(query).first
+        begin
+          query.repository.read(query).first
+        rescue Query::InvalidConditionsError
+          nil
+        end
       end
     end
 
@@ -416,7 +420,11 @@ def last(*args)
       if limit_specified
         all(query)
       else
-        query.repository.read(query).last
+        begin
+          query.repository.read(query).last
+        rescue Query::InvalidConditionsError
+          nil
+        end
       end
     end
 
diff --git a/lib/dm-core/repository.rb b/lib/dm-core/repository.rb
index 7de061d77..83b5446bb 100644
--- a/lib/dm-core/repository.rb
+++ b/lib/dm-core/repository.rb
@@ -158,7 +158,7 @@ def create(resources)
     #
     # @api semipublic
     def read(query)
-      raise InvalidConditionsError unless query.valid?
+      raise Query::InvalidConditionsError unless query.valid?
       query.model.load(adapter.read(query), query)
     end