Composite primary key migration (#616)

spec/migrator/create_table_statement_spec.cr

@@ -74,6 +74,41 @@ describe Avram::Migrator::CreateTableStatement do
     SQL
   end
 
+  it "can create tables with composite primary keys" do
+    built = Avram::Migrator::CreateTableStatement.new(:users).build do
+      add id1 : Int64
+      add id2 : UUID
+      composite_primary_key :id1, :id2
+    end
+
+    built.statements.size.should eq 1
+    built.statements.first.should eq <<-SQL
+    CREATE TABLE users (
+      id1 bigint NOT NULL,
+      id2 uuid NOT NULL,
+      PRIMARY KEY (id1, id2));
+    SQL
+  end
+
+  it "can create tables with composite primary keys with primary key constraint at end" do
+    built = Avram::Migrator::CreateTableStatement.new(:users).build do
+      add id1 : Int64
+      add id2 : UUID
+      composite_primary_key :id1, :id2
+
+      add example : String
+    end
+
+    built.statements.size.should eq 1
+    built.statements.first.should eq <<-SQL
+    CREATE TABLE users (
+      id1 bigint NOT NULL,
+      id2 uuid NOT NULL,
+      example text NOT NULL,
+      PRIMARY KEY (id1, id2));
+    SQL
+  end
+
   it "sets default values" do
     built = Avram::Migrator::CreateTableStatement.new(:users).build do
       add name : String, default: "name"
@@ -174,6 +209,22 @@ describe Avram::Migrator::CreateTableStatement do
       built.statements[5].should eq "CREATE INDEX comments_line_item_id_index ON comments USING btree (line_item_id);"
     end
 
+    it "can create tables with association on composite primary keys" do
+      built = Avram::Migrator::CreateTableStatement.new(:comments).build do
+        add_belongs_to user : User, on_delete: :cascade
+        add id2 : Int64
+        composite_primary_key :user_id, :id2
+      end
+
+      built.statements.size.should eq 2
+      built.statements.first.should eq <<-SQL
+      CREATE TABLE comments (
+        user_id bigint NOT NULL REFERENCES users ON DELETE CASCADE,
+        id2 bigint NOT NULL,
+        PRIMARY KEY (user_id, id2));
+      SQL
+    end
+
     it "raises error when on_delete strategy is invalid or nil" do
       expect_raises Exception, "on_delete: :cascad is not supported. Please use :do_nothing, :cascade, :restrict, or :nullify" do
         Avram::Migrator::CreateTableStatement.new(:users).build do

src/avram/migrator/create_table_statement.cr

@@ -6,6 +6,7 @@ class Avram::Migrator::CreateTableStatement
   include Avram::Migrator::MissingOnDeleteWithBelongsToError
 
   private getter rows = [] of String
+  private getter constraints = [] of String
 
   def initialize(@table_name : Symbol)
   end
@@ -55,6 +56,8 @@ class Avram::Migrator::CreateTableStatement
     String.build do |statement|
       statement << initial_table_statement
       statement << rows.join(",\n")
+      statement << ",\n" if !constraints.empty?
+      statement << constraints.join(", \n")
       statement << ");"
     end
   end
@@ -71,6 +74,13 @@ class Avram::Migrator::CreateTableStatement
       .build
   end
 
+  macro composite_primary_key(*columns)
+    {% if columns.size < 2 %}
+    {% raise "composite_primary_key expected at least two primary keys, instead got #{columns.size}" %}
+    {% end %}
+    constraints << "  PRIMARY KEY ({{columns.join(", ").id}})"
+  end
+
   macro add_timestamps
     add created_at : Time
     add updated_at : Time