Add DB::Serializable (#115)

This commit is contained in:
Nick Clifford 2019-10-31 09:34:23 -05:00 committed by Brian J. Cardiff
parent 2b95d69e68
commit e1832fc359
4 changed files with 402 additions and 1 deletions

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@ -4,6 +4,6 @@ version: 0.7.0
authors: authors:
- Brian J. Cardiff <bcardiff@manas.tech> - Brian J. Cardiff <bcardiff@manas.tech>
crystal: 0.24.0 crystal: 0.25.0
license: MIT license: MIT

220
spec/serializable_spec.cr Normal file
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@ -0,0 +1,220 @@
require "./spec_helper"
require "base64"
require "json"
class SimpleModel
include DB::Serializable
property c0 : Int32
property c1 : String
end
class NonStrictModel
include DB::Serializable
include DB::Serializable::NonStrict
property c1 : Int32
property c2 : String
end
class ModelWithDefaults
include DB::Serializable
property c0 : Int32 = 10
property c1 : String = "c"
end
class ModelWithNilables
include DB::Serializable
property c0 : Int32? = 10
property c1 : String?
end
class ModelWithNilUnionTypes
include DB::Serializable
property c0 : Int32 | Nil = 10
property c1 : String | Nil
end
class ModelWithKeys
include DB::Serializable
@[DB::Field(key: "c0")]
property foo : Int32
@[DB::Field(key: "c1")]
property bar : String
end
class ModelWithConverter
module Base64Converter
def self.from_rs(rs)
Base64.decode(rs.read(String))
end
end
include DB::Serializable
@[DB::Field(converter: ModelWithConverter::Base64Converter)]
property c0 : Slice(UInt8)
property c1 : String
end
class ModelWithInitialize
include DB::Serializable
property c0 : Int32
property c1 : String
def_equals c0, c1
def initialize(@c0, @c1)
end
end
class ModelWithJSON
include JSON::Serializable
include DB::Serializable
property c0 : Int32
property c1 : String
end
macro from_dummy(query, type)
with_dummy do |db|
rs = db.query({{ query }})
rs.move_next
%obj = {{ type }}.new(rs)
rs.close
%obj
end
end
macro expect_model(query, t, values)
%obj = from_dummy({{ query }}, {{ t }})
%obj.should be_a({{ t }})
{% for key, value in values %}
%obj.{{key.id}}.should eq({{value}})
{% end %}
end
describe "DB::Serializable" do
it "should initialize a simple model" do
expect_model("1,a", SimpleModel, {c0: 1, c1: "a"})
end
it "should fail to initialize a simple model if types do not match" do
expect_raises ArgumentError do
from_dummy("b,a", SimpleModel)
end
end
it "should fail to initialize a simple model if there is a missing column" do
expect_raises DB::MappingException do
from_dummy("1", SimpleModel)
end
end
it "should fail to initialize a simple model if there is an unexpected column" do
expect_raises DB::MappingException do
from_dummy("1,a,b", SimpleModel)
end
end
it "should initialize a non-strict model if there is an unexpected column" do
expect_model("1,2,a,b", NonStrictModel, {c1: 2, c2: "a"})
end
it "should initialize a model with default values" do
expect_model("1,a", ModelWithDefaults, {c0: 1, c1: "a"})
end
it "should initialize a model using default values if columns are missing" do
expect_model("1", ModelWithDefaults, {c0: 1, c1: "c"})
end
it "should initialize a model using default values if values are nil and types are non nilable" do
expect_model("1,NULL", ModelWithDefaults, {c0: 1, c1: "c"})
end
it "should initialize a model with nilables if columns are missing" do
expect_model("1", ModelWithNilables, {c0: 1, c1: nil})
end
it "should initialize a model with nilables ignoring default value if NULL" do
expect_model("NULL,a", ModelWithNilables, {c0: nil, c1: "a"})
end
it "should initialize a model with nil union types if columns are missing" do
expect_model("1", ModelWithNilUnionTypes, {c0: 1, c1: nil})
end
it "should initialize a model with nil union types ignoring default value if NULL" do
expect_model("NULL,a", ModelWithNilUnionTypes, {c0: nil, c1: "a"})
end
it "should initialize a model with different keys" do
expect_model("1,a", ModelWithKeys, {foo: 1, bar: "a"})
end
it "should initialize a model with a value converter" do
expect_model("Zm9v,a", ModelWithConverter, {c0: "foo".to_slice, c1: "a"})
end
it "should initialize a model with an initialize" do
obj1 = from_dummy("1,a", ModelWithInitialize)
obj2 = ModelWithInitialize.new(1, "a")
obj1.should eq obj2
end
it "should initialize a model with JSON serialization also defined" do
expect_model("1,a", ModelWithJSON, {c0: 1, c1: "a"})
end
it "should initialize multiple instances from a single resultset" do
with_dummy do |db|
db.query("1,a 2,b") do |rs|
objs = SimpleModel.from_rs(rs)
objs.size.should eq(2)
objs[0].c0.should eq(1)
objs[0].c1.should eq("a")
objs[1].c0.should eq(2)
objs[1].c1.should eq("b")
end
end
end
it "Class.from_rs should close resultset" do
with_dummy do |db|
rs = db.query("1,a 2,b")
objs = SimpleModel.from_rs(rs)
rs.closed?.should be_true
objs.size.should eq(2)
objs[0].c0.should eq(1)
objs[0].c1.should eq("a")
objs[1].c0.should eq(2)
objs[1].c1.should eq("b")
end
end
it "should initialize from a query_one" do
with_dummy do |db|
obj = db.query_one "1,a", as: SimpleModel
obj.c0.should eq(1)
obj.c1.should eq("a")
end
end
it "should initialize from a query_all" do
with_dummy do |db|
objs = db.query_all "1,a 2,b", as: SimpleModel
objs.size.should eq(2)
objs[0].c0.should eq(1)
objs[0].c1.should eq("a")
objs[1].c0.should eq(2)
objs[1].c1.should eq("b")
end
end
end

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@ -199,3 +199,4 @@ require "./db/pool_unprepared_statement"
require "./db/result_set" require "./db/result_set"
require "./db/error" require "./db/error"
require "./db/mapping" require "./db/mapping"
require "./db/serializable"

180
src/db/serializable.cr Normal file
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@ -0,0 +1,180 @@
module DB
annotation Field
end
# The `DB::Serialization` module automatically generates methods for DB serialization when included.
#
# Once included, `ResultSet#read(t)` populates properties of the class from the
# `ResultSet`.
#
# ### Example
#
# ```crystal
# require "db"
#
# class Employee
# include DB::Serializable
#
# property title : String
# property name : String
# end
#
# employees = Employee.from_rs(db.query("SELECT title, name FROM employees"))
# employees[0].title # => "Manager"
# employees[0].name # => "John"
# ```
#
# ### Usage
#
# `DB::Serializable` was designed in analogue with `JSON::Serializable`, so usage is identical.
# However, like `DB.mapping`, `DB::Serializable` is **strict by default**, so extra columns will raise `DB::MappingException`s.
#
# Similar to `JSON::Field`, there is an annotation `DB::Field` that can be used to set serialization behavior
# on individual instance variables.
#
# ```crystal
# class Employee
# include DB::Serializable
#
# property title : String
#
# @[DB::Field(key: "firstname")]
# property name : String?
# end
# ```
#
# `DB::Field` properties:
# * **ignore**: if `true`, skip this field in serialization and deserialization (`false` by default)
# * **key**: defines which column to read from a `ResultSet` (name of the instance variable by default)
# * **converter**: defines an alternate type for parsing results. The given type must define `#from_rs(DB::ResultSet)` and return an instance of the included type.
#
# ### `DB::Serializable::NonStrict`
#
# Including this module is functionally identical to passing `{strict: false}` to `DB.mapping`: extra columns will not raise.
#
# ```crystal
# class Employee
# include DB::Serializable
# include DB::Serializable::NonStrict
#
# property title : String
# property name : String
# end
#
# # does not raise!
# employees = Employee.from_rs(db.query("SELECT title, name, age FROM employees"))
# ```
module Serializable
macro included
include ::DB::Mappable
# Define a `new` and `from_rs` directly in the type, like JSON::Serializable
# For proper overload resolution
def self.new(rs : ::DB::ResultSet)
instance = allocate
instance.initialize(__set_for_db_serializable: rs)
GC.add_finalizer(instance) if instance.responds_to?(:finalize)
instance
end
def self.from_rs(rs : ::DB::ResultSet)
objs = Array(self).new
rs.each do
objs << self.new(rs)
end
objs
ensure
rs.close
end
# Inject the class methods into subclasses as well
macro inherited
def self.new(rs : ::DB::ResultSet)
super
end
def self.from_rs(rs : ::DB::Result_set)
super
end
end
end
def initialize(*, __set_for_db_serializable rs : ::DB::ResultSet)
{% begin %}
{% properties = {} of Nil => Nil %}
{% for ivar in @type.instance_vars %}
{% ann = ivar.annotation(::DB::Field) %}
{% unless ann && ann[:ignore] %}
{%
properties[ivar.id] = {
type: ivar.type,
key: ((ann && ann[:key]) || ivar).id.stringify,
default: ivar.default_value,
nilable: ivar.type.nilable?,
converter: ann && ann[:converter],
}
%}
{% end %}
{% end %}
{% for name, value in properties %}
%var{name} = nil
%found{name} = false
{% end %}
rs.each_column do |col_name|
case col_name
{% for name, value in properties %}
when {{value[:key]}}
%found{name} = true
%var{name} =
{% if value[:converter] %}
{{value[:converter]}}.from_rs(rs)
{% elsif value[:nilable] || value[:default] != nil %}
rs.read(::Union({{value[:type]}} | Nil))
{% else %}
rs.read({{value[:type]}})
{% end %}
{% end %}
else
rs.read # Advance set, but discard result
on_unknown_db_column(col_name)
end
end
{% for key, value in properties %}
{% unless value[:nilable] || value[:default] != nil %}
if %var{key}.is_a?(Nil) && !%found{key}
raise ::DB::MappingException.new("missing result set attribute: {{(value[:key] || key).id}}")
end
{% end %}
{% end %}
{% for key, value in properties %}
{% if value[:nilable] %}
{% if value[:default] != nil %}
@{{key}} = %found{key} ? %var{key} : {{value[:default]}}
{% else %}
@{{key}} = %var{key}
{% end %}
{% elsif value[:default] != nil %}
@{{key}} = %var{key}.is_a?(Nil) ? {{value[:default]}} : %var{key}
{% else %}
@{{key}} = %var{key}.as({{value[:type]}})
{% end %}
{% end %}
{% end %}
end
protected def on_unknown_db_column(col_name)
raise ::DB::MappingException.new("unknown result set attribute: #{col_name}")
end
module NonStrict
protected def on_unknown_db_column(col_name)
end
end
end
end