re
/
gorm
forked from mirror/gorm
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Update README for Association Mode

This commit is contained in:
Jinzhu 2015-12-26 17:13:41 +08:00
parent a563efdd27
commit e8fe7c5e34
1 changed files with 36 additions and 32 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

68
README.md
View File

@ -594,38 +594,6 @@ db.Model(&user).Related(&languages, "Languages")
// `Languages` is user's column name, this column's tag defined join table like this `gorm:"many2many:user_languages;"`
```
There is also a mode used to handle many to many relations easily
```go
// Query
db.Model(&user).Association("Languages").Find(&languages)
// same as `db.Model(&user).Related(&languages, "Languages")`
db.Where("name = ?", "ZH").First(&languageZH)
db.Where("name = ?", "EN").First(&languageEN)
// Append
db.Model(&user).Association("Languages").Append([]Language{languageZH, languageEN})
db.Model(&user).Association("Languages").Append([]Language{{Name: "DE"}})
db.Model(&user).Association("Languages").Append(Language{Name: "DE"})
// Delete
db.Model(&user).Association("Languages").Delete([]Language{languageZH, languageEN})
db.Model(&user).Association("Languages").Delete(languageZH, languageEN)
// Replace
db.Model(&user).Association("Languages").Replace([]Language{languageZH, languageEN})
db.Model(&user).Association("Languages").Replace(Language{Name: "DE"}, languageEN)
// Count
db.Model(&user).Association("Languages").Count()
// Return the count of languages the user has
// Clear
db.Model(&user).Association("Languages").Clear()
// Remove all relations between the user and languages
```
### Polymorphism
Supports polymorphic has-many and has-one associations.
@ -652,6 +620,42 @@ Supports polymorphic has-many and has-one associations.
```
Note: polymorphic belongs-to and many-to-many are explicitly NOT supported, and will throw errors.
## Association Mode
Association Mode contains some helper methods to handle relationship things easily.
```go
// Start Association Mode
db.Model(&source).Association(fieldNameOfRelationship)
db.Model(&user).Association("Languages")
// source (user) need to have a valid primary key
// fieldNameOfRelationship ("Languages") need to be a valid relationship of source
// If not, it will return error, check it with:
// db.Model(&user).Association("Languages").Error
// Query - Find out all related associations
db.Model(&user).Association("Languages").Find(&languages)
// Append - Append new associations for many2many, has_many, will replace current association for has_one, belongs_to
db.Model(&user).Association("Languages").Append([]Language{languageZH, languageEN})
db.Model(&user).Association("Languages").Append(Language{Name: "DE"})
// Delete - Remove relationship between source & passed arguments, won't delete those arguments
db.Model(&user).Association("Languages").Delete([]Language{languageZH, languageEN})
db.Model(&user).Association("Languages").Delete(languageZH, languageEN)
// Replace - Replace current associations with new one
db.Model(&user).Association("Languages").Replace([]Language{languageZH, languageEN})
db.Model(&user).Association("Languages").Replace(Language{Name: "DE"}, languageEN)
// Count - Return the count of current associations
db.Model(&user).Association("Languages").Count()
// Clear - Remove relationship between source & current associations, won't delete those associations
db.Model(&user).Association("Languages").Clear()
```
## Advanced Usage
## FirstOrInit