จากรหัสที่มาสาขา Rails ต้นแบบฉันพบ:
abstract mysql_adapter
#activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
NATIVE_DATABASE_TYPES = {
primary_key: "bigint auto_increment PRIMARY KEY",
string: { name: "varchar", limit: 255 },
text: { name: "text", limit: 65535 },
integer: { name: "int", limit: 4 },
float: { name: "float" },
decimal: { name: "decimal" },
datetime: { name: "datetime" },
timestamp: { name: "timestamp" },
time: { name: "time" },
date: { name: "date" },
binary: { name: "blob", limit: 65535 },
boolean: { name: "tinyint", limit: 1 },
json: { name: "json" },
}
# Maps logical Rails types to MySQL-specific data types.
def type_to_sql(type, limit = nil, precision = nil, scale = nil, unsigned = nil)
sql = case type.to_s
when 'integer'
integer_to_sql(limit)
when 'text'
text_to_sql(limit)
when 'blob'
binary_to_sql(limit)
when 'binary'
if (0..0xfff) === limit
"varbinary(#{limit})"
else
binary_to_sql(limit)
end
else
super(type, limit, precision, scale)
end
sql << ' unsigned' if unsigned && type != :primary_key
sql
end
# and integer ...
def integer_to_sql(limit) # :nodoc:
case limit
when 1; 'tinyint'
when 2; 'smallint'
when 3; 'mediumint'
when nil, 4; 'int'
when 5..8; 'bigint'
else raise(ActiveRecordError, "No integer type has byte size #{limit}")
end
end
# and text ..
def text_to_sql(limit) # :nodoc:
case limit
when 0..0xff; 'tinytext'
when nil, 0x100..0xffff; 'text'
when 0x10000..0xffffff; 'mediumtext'
when 0x1000000..0xffffffff; 'longtext'
else raise(ActiveRecordError, "No text type has byte length #{limit}")
end
end
# and binary ...
def binary_to_sql(limit) # :nodoc:
case limit
when 0..0xff; "tinyblob"
when nil, 0x100..0xffff; "blob"
when 0x10000..0xffffff; "mediumblob"
when 0x1000000..0xffffffff; "longblob"
else raise(ActiveRecordError, "No binary type has byte length #{limit}")
end
end
superในtype_to_sqlวิธีการ
#activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
def type_to_sql(type, limit = nil, precision = nil, scale = nil) #:nodoc:
type = type.to_sym if type
if native = native_database_types[type]
column_type_sql = (native.is_a?(Hash) ? native[:name] : native).dup
if type == :decimal # ignore limit, use precision and scale
scale ||= native[:scale]
if precision ||= native[:precision]
if scale
column_type_sql << "(#{precision},#{scale})"
else
column_type_sql << "(#{precision})"
end
elsif scale
raise ArgumentError, "Error adding decimal column: precision cannot be empty if scale is specified"
end
elsif [:datetime, :time].include?(type) && precision ||= native[:precision]
if (0..6) === precision
column_type_sql << "(#{precision})"
else
raise(ActiveRecordError, "No #{native[:name]} type has precision of #{precision}. The allowed range of precision is from 0 to 6")
end
elsif (type != :primary_key) && (limit ||= native.is_a?(Hash) && native[:limit])
column_type_sql << "(#{limit})"
end
column_type_sql
else
type.to_s
end
end
:stringและ:textและฉันไม่สามารถหาสิ่งอื่นนอกเหนือจากนี้ ดังนั้นฉันแค่สงสัยในการอ้างอิงในอนาคต