140 lines
4.6 KiB
Markdown
140 lines
4.6 KiB
Markdown
## Model
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Model files are simple data files used to store result of SQL queries. They are
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autogenerated from database tables and enums.
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### Table model files
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Following rules are applied to generate model files from database tables:
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- for every table there is one Go file generated. File name is in snake case of the table name.
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- every model file contains one struct type.
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Type name is a camel case of table name.
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- for every column of table there is a field in model struct. Field name is camel case of column name.
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See below table for type mapping.
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- fields are pointer types, if they relate to column that can be NULL.
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- fields corresponds to primary key columns are tagged with `sql:"primary_key"`.
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_This tag is used during query execution to group row results into desired arbitrary structure.
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See more at [Execution](https://github.com/go-jet/jet/wiki/Execution):_
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##### Mappings of database types to Go types
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| Database type(postgres) | Go type |
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| ----------------------------------------------- | -------------------------------------------------- |
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| boolean | bool |
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| smallint | int16 |
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| integer | int32 |
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| bigint | int64 |
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| real | float32 |
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| numeric, decimal, double precision | float64 |
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| date, timestamp, time(with or without timezone) | time.Time |
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| bytea | []byte |
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| uuid | uuid.UUID |
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| enum | enum name |
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| text, character, character varying, | |
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| and all remaining types | string |
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#### Example:
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Sql table `address`:
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```
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CREATE TABLE dvds.address
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(
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address_id serial NOT NULL DEFAULT,
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address character varying(50) NOT NULL,
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address2 character varying(50),
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district character varying(20) NOT NULL,
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city_id smallint NOT NULL,
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postal_code character varying(10),
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phone character varying(20) NOT NULL,
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last_update timestamp without time zone NOT NULL DEFAULT now(),
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CONSTRAINT address_pkey PRIMARY KEY (address_id)
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)
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```
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Autogenerated model file `address.go`:
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```
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package model
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import (
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"time"
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)
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type Address struct {
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AddressID int32 `sql:"primary_key"`
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Address string
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Address2 *string
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District string
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CityID int16
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PostalCode *string
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Phone string
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LastUpdate time.Time
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}
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```
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### Enum model files
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Following rules are applied to generate model files from database enums:
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- for every enum there is one Go file generated. File name is a snake case of enum name.
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- every file contains one renamed string type. Type name is a camel case of enum name.
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Enum type has two helper methods to:
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- initialize correctly from database query result
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- easily convert enum to string.
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- for every enum value there is one constant defined.
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Name of the constant is in format [camel case of enum_name]_[camel case of enum_value_name].
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#### Example
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Enum `mpaa_rating`:
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```
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CREATE TYPE dvds.mpaa_rating AS ENUM
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('G', 'PG', 'PG-13', 'R', 'NC-17');
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```
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Autogenerated model file `mpaa_rating.go`
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```
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package model
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import "errors"
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type MpaaRating string
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const (
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MpaaRating_G MpaaRating = "G"
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MpaaRating_Pg MpaaRating = "PG"
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MpaaRating_Pg13 MpaaRating = "PG-13"
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MpaaRating_R MpaaRating = "R"
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MpaaRating_Nc17 MpaaRating = "NC-17"
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)
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func (e *MpaaRating) Scan(value interface{}) error {
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if v, ok := value.(string); !ok {
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return errors.New("Invalid data for MpaaRating enum")
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} else {
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switch string(v) {
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case "G":
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*e = MpaaRating_G
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case "PG":
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*e = MpaaRating_Pg
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case "PG-13":
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*e = MpaaRating_Pg13
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case "R":
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*e = MpaaRating_R
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case "NC-17":
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*e = MpaaRating_Nc17
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default:
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return errors.New("Inavlid data " + string(v) + "for MpaaRating enum")
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}
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return nil
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}
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}
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func (e MpaaRating) String() string {
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return string(e)
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}
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```
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