Clean up Avram::Model to prepare for database views (#552)

spec/model_spec.cr

@@ -63,24 +63,6 @@ describe Avram::Model do
     user.available_for_hire?.should be_false
   end
 
-  it "can be used for params" do
-    now = Time.utc
-
-    user = User.new id: 123_i64,
-      name: "Name",
-      age: 24,
-      year_born: 1990_i16,
-      joined_at: now,
-      created_at: now,
-      updated_at: now,
-      nickname: "nick",
-      total_score: nil,
-      average_score: nil,
-      available_for_hire: nil
-
-    user.to_param.should eq "123"
-  end
-
   it "sets up getters that parse the values" do
     user = QueryMe.new id: 123_i64,
       created_at: Time.utc,

src/avram/base_query_template.cr

@@ -6,7 +6,10 @@ class Avram::BaseQueryTemplate
 
       def_clone
       include Avram::Queryable({{ type }})
-      include Avram::PrimaryKeyQueryable({{ type }})
+
+      {% if type.resolve.has_constant?("PRIMARY_KEY_NAME") %}
+        include Avram::PrimaryKeyQueryable({{ type }})
+      {% end %}
 
       macro generate_criteria_method(query_class, name, type)
         def \{{ name }}

src/avram/model.cr

@@ -8,82 +8,27 @@ abstract class Avram::Model
   include Avram::Polymorphic
   include Avram::SchemaEnforcer
 
-  abstract def id
-
   macro inherited
     COLUMNS = [] of Nil # types are not checked in macros
     ASSOCIATIONS = [] of Nil # types are not checked in macros
   end
 
-  def_equals id, model_name
+  def self.primary_key_name : Symbol?
+    nil
+  end
 
   def model_name
     self.class.name
   end
 
-  def to_param
-    id.to_s
-  end
-
-  # Reload the model with the latest information from the database
-  #
-  # This method will return a new model instance with the
-  # latest data from the database. Note that this does
-  # **not** change the original instance, so you may need to
-  # assign the result to a variable or work directly with the return value.
-  #
-  # Example:
-  #
-  # ```crystal
-  # user = SaveUser.create!(name: "Original")
-  # SaveUser.update!(user, name: "Updated")
-  #
-  # # Will be "Original"
-  # user.name
-  # # Will return "Updated"
-  # user.reload.name # Will be "Updated"
-  # # Will still be "Original" since the 'user' is the same model instance.
-  # user.name
-  #
-  # Instead re-assign the variable. Now 'name' will return "Updated" since
-  # 'user' references the reloaded model.
-  # user = user.reload
-  # user.name
-  # ```
+  # Refer to `PrimaryKeyMethods#reload`
   def reload : self
-    base_query_class.find(id)
+    {% raise "Unable to call Avram::Model#reload on #{@type.name} because it does not have a primary key." %}
   end
 
-  # Same as `reload` but allows passing a block to customize the query.
-  #
-  # This is almost always used to preload additional relationships.
-  #
-  # Example:
-  #
-  # ```crystal
-  # user = SaveUser.create(params)
-  #
-  # # We want to display the list of articles the user has commented on, so let's #
-  # # preload them to avoid N+1 performance issues
-  # user = user.reload(&.preload_comments(CommentQuery.new.preload_article))
-  #
-  # # Now we can safely get all the comment authors
-  # user.comments.map(&.article)
-  # ```
-  #
-  # Note that the yielded query is the `BaseQuery` so it will not have any
-  # methods defined on your customized query. This is usually fine since
-  # typically reload only uses preloads.
-  #
-  # If you do need to do something more custom you can manually reload:
-  #
-  # ```crystal
-  # user = SaveUser.create!(name: "Helen")
-  # UserQuery.new.some_custom_preload_method.find(user.id)
-  # ```
-  def reload : self
-    query = yield base_query_class.new
-    query.find(id)
+  # Refer to `PrimaryKeyMethods#reload`
+  def reload(&block) : self
+    {% raise "Unable to call Avram::Model#reload on #{@type.name} because it does not have a primary key." %}
   end
 
   macro table(table_name = nil)
@@ -115,13 +60,11 @@ abstract class Avram::Model
     column {{ type_declaration.var }} : {{ type_declaration.type }}, autogenerated: true
     alias PrimaryKeyType = {{ type_declaration.type }}
 
-    def self.primary_key_name : Symbol
+    def self.primary_key_name : Symbol?
       :{{ type_declaration.var.stringify }}
     end
 
-    def primary_key_name : Symbol
-      self.class.primary_key_name
-    end
+    include Avram::PrimaryKeyMethods
 
     # If not using default 'id' primary key
     {% if type_declaration.var.id != "id".id %}

src/avram/primary_key_methods.cr

@@ -0,0 +1,68 @@
+module Avram::PrimaryKeyMethods
+  def_equals id, model_name
+
+  def primary_key_name : Symbol?
+    self.class.primary_key_name
+  end
+
+  # Reload the model with the latest information from the database
+  #
+  # This method will return a new model instance with the
+  # latest data from the database. Note that this does
+  # **not** change the original instance, so you may need to
+  # assign the result to a variable or work directly with the return value.
+  #
+  # Example:
+  #
+  # ```crystal
+  # user = SaveUser.create!(name: "Original")
+  # SaveUser.update!(user, name: "Updated")
+  #
+  # # Will be "Original"
+  # user.name
+  # # Will return "Updated"
+  # user.reload.name # Will be "Updated"
+  # # Will still be "Original" since the 'user' is the same model instance.
+  # user.name
+  #
+  # Instead re-assign the variable. Now 'name' will return "Updated" since
+  # 'user' references the reloaded model.
+  # user = user.reload
+  # user.name
+  # ```
+  def reload : self
+    base_query_class.find(id)
+  end
+
+  # Same as `reload` but allows passing a block to customize the query.
+  #
+  # This is almost always used to preload additional relationships.
+  #
+  # Example:
+  #
+  # ```crystal
+  # user = SaveUser.create(params)
+  #
+  # # We want to display the list of articles the user has commented on, so let's #
+  # # preload them to avoid N+1 performance issues
+  # user = user.reload(&.preload_comments(CommentQuery.new.preload_article))
+  #
+  # # Now we can safely get all the comment authors
+  # user.comments.map(&.article)
+  # ```
+  #
+  # Note that the yielded query is the `BaseQuery` so it will not have any
+  # methods defined on your customized query. This is usually fine since
+  # typically reload only uses preloads.
+  #
+  # If you do need to do something more custom you can manually reload:
+  #
+  # ```crystal
+  # user = SaveUser.create!(name: "Helen")
+  # UserQuery.new.some_custom_preload_method.find(user.id)
+  # ```
+  def reload : self
+    query = yield base_query_class.new
+    query.find(id)
+  end
+end

src/avram/schema_enforcer/ensure_uuid_primary_key_has_default.cr

@@ -1,6 +1,6 @@
 class Avram::SchemaEnforcer::EnsureUUIDPrimaryKeyHasDefault < Avram::SchemaEnforcer::Validation
   def validate!
-    return unless uuid_primary_key? && missing_column_default?
+    return unless has_primary_key? && uuid_primary_key? && missing_column_default?
 
     message = <<-TEXT
     Primary key on the '#{table_name.colorize.bold}' table has the type set as uuid but does not have a default value.
@@ -22,6 +22,10 @@ class Avram::SchemaEnforcer::EnsureUUIDPrimaryKeyHasDefault < Avram::SchemaEnfor
     raise Avram::SchemaMismatchError.new(message)
   end
 
+  def has_primary_key?
+    !model_class.primary_key_name.nil?
+  end
+
   def uuid_primary_key?
     primary_key_info.data_type == "uuid"
   end