129 lines
3.7 KiB
Markdown
129 lines
3.7 KiB
Markdown
# Deepcopier
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[](http://travis-ci.org/ulule/deepcopier)
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This package is meant to make copying of structs to/from others structs a bit easier.
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## Installation
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```bash
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go get -u github.com/ulule/deepcopier
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```
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## Usage
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```golang
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// Deep copy instance1 into instance2
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Copy(instance1).To(instance2)
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// Deep copy instance1 into instance2 and passes the following context (which
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// is basically a map[string]interface{}) as first argument
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// to methods of instance2 that defined the struct tag "context".
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Copy(instance1).WithContext(map[string]interface{}{"foo": "bar"}).To(instance2)
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// Deep copy instance2 into instance1
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Copy(instance1).From(instance2)
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// Deep copy instance2 into instance1 and passes the following context (which
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// is basically a map[string]interface{}) as first argument
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// to methods of instance1 that defined the struct tag "context".
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Copy(instance1).WithContext(map[string]interface{}{"foo": "bar"}).From(instance2)
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```
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Available options for `deepcopier` struct tag:
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| Option | Description |
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| --------- | -------------------------------------------------------------------- |
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| `field` | Field or method name in source instance |
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| `skip` | Ignores the field |
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| `context` | Takes a `map[string]interface{}` as first argument (for methods) |
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| `force` | Set the value of a `sql.Null*` field (instead of copying the struct) |
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**Options example:**
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```golang
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type Source struct {
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Name string
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SkipMe string
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SQLNullStringToSQLNullString sql.NullString
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SQLNullStringToString sql.NullString
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}
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func (Source) MethodThatTakesContext(c map[string]interface{}) string {
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return "whatever"
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}
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type Destination struct {
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FieldWithAnotherNameInSource string `deepcopier:"field:Name"`
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SkipMe string `deepcopier:"skip"`
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MethodThatTakesContext string `deepcopier:"context"`
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SQLNullStringToSQLNullString sql.NullString
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SQLNullStringToString string `deepcopier:"force"`
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}
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```
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Example:
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```golang
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package main
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import (
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"fmt"
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"github.com/ulule/deepcopier"
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)
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// Model
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type User struct {
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// Basic string field
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Name string
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// Deepcopier supports https://golang.org/pkg/database/sql/driver/#Valuer
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Email sql.NullString
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}
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func (u *User) MethodThatTakesContext(ctx map[string]interface{}) string {
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// do whatever you want
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return "hello from this method"
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}
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// Resource
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type UserResource struct {
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DisplayName string `deepcopier:"field:Name"`
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SkipMe string `deepcopier:"skip"`
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MethodThatTakesContext string `deepcopier:"context"`
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Email string `deepcopier:"force"`
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}
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func main() {
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user := &User{
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Name: "gilles",
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Email: sql.NullString{
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Valid: true,
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String: "gilles@example.com",
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},
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}
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resource := &UserResource{}
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deepcopier.Copy(user).To(resource)
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fmt.Println(resource.DisplayName)
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fmt.Println(resource.Email)
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}
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```
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Looking for more information about the usage?
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We wrote [an introduction article](https://github.com/ulule/deepcopier/blob/master/examples/rest-usage/README.rst).
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Have a look and feel free to give us your feedback.
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## Contributing
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* Ping us on twitter [@oibafsellig](https://twitter.com/oibafsellig), [@thoas](https://twitter.com/thoas)
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* Fork the [project](https://github.com/ulule/deepcopier)
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* Help us improving and fixing [issues](https://github.com/ulule/deepcopier/issues)
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Don't hesitate ;)
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