feat: CreateMany

[sljeff]

Make sure these boxes checked before submitting your pull request.

• Do only one thing
• No API-breaking changes
• New code/logic commented & tested

For significant changes like big bug fixes, new features, please open an issue to make an agreement on an implementation design/plan first before starting it.

What did this pull request do?

CreateMany

// mysql and sqlite: insert multiple; insert multiple ignore duplicate
// postgresql and mssql do not support ignore
db.CreateMany([]interface{}{&user1, &user2, &user3}, gorm.IGNORE)
db.CreateMany([]interface{}{&user1, &user2, &user3})

// mysql: insert on conflict update
db.CreateMany([]interface{}{&user1, &user2, &user3}, &User{UpdatedAt: now})

// postgresql: insert on confilct update
db.CreateMany([]interface{}{&user1, &user2, &user3}, 'constraint_name', &User{UpdatedAt: now})

// Caution: mssql db driver will not raise error on duplicate
db.CreateMany([]interface{}{&user1, &user1, &user1})

[codecov]

Codecov Report

Merging #6 into master will increase coverage by 0.08%.
The diff coverage is 95.58%.

@@            Coverage Diff             @@
##           master       #6      +/-   ##
==========================================
+ Coverage   85.97%   86.06%   +0.08%     
==========================================
  Files          24       24              
  Lines        3601     3645      +44     
==========================================
+ Hits         3096     3137      +41     
- Misses        398      400       +2     
- Partials      107      108       +1

Impacted Files	Coverage Δ
scope.go	89.44% <100%> (+0.15%)	⬆️
main.go	83.4% <80%> (-0.41%)	⬇️
callback_create.go	92.77% <97.82%> (+0.91%)	⬆️

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[sljeff]

https://github.com/jinzhu/gorm/issues/255

[Arcayr]

Could you make a PR for this on @jinzhu's gorm repo?

Much appreciated.

[sljeff]

Could you make a PR for this on @jinzhu's gorm repo?

Much appreciated.

GORM v2 is on going: https://github.com/jinzhu/gorm/issues/2886#issue-565836194