103 lines
2.0 KiB
Markdown
103 lines
2.0 KiB
Markdown
# pointerstructure [](https://godoc.org/github.com/mitchellh/pointerstructure)
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pointerstructure is a Go library for identifying a specific value within
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any Go structure using a string syntax.
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pointerstructure is based on
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[JSON Pointer (RFC 6901)](https://tools.ietf.org/html/rfc6901), but
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reimplemented for Go.
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The goal of pointerstructure is to provide a single, well-known format
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for addressing a specific value. This can be useful for user provided
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input on structures, diffs of structures, etc.
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## Features
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* Get the value for an address
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* Set the value for an address within an existing structure
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* Delete the value at an address
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* Sorting a list of addresses
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## Installation
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Standard `go get`:
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```
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$ go get github.com/mitchellh/pointerstructure
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```
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## Usage & Example
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For usage and examples see the [Godoc](http://godoc.org/github.com/mitchellh/pointerstructure).
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A quick code example is shown below:
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```go
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complex := map[string]interface{}{
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"alice": 42,
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"bob": []interface{}{
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map[string]interface{}{
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"name": "Bob",
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},
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},
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}
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value, err := pointerstructure.Get(complex, "/bob/0/name")
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if err != nil {
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panic(err)
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}
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fmt.Printf("%s", value)
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// Output:
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// Bob
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```
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Continuing the example above, you can also set values:
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```go
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value, err = pointerstructure.Set(complex, "/bob/0/name", "Alice")
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if err != nil {
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panic(err)
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}
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value, err = pointerstructure.Get(complex, "/bob/0/name")
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if err != nil {
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panic(err)
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}
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fmt.Printf("%s", value)
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// Output:
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// Alice
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```
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The library also supports `Get` operations on structs including using the `pointer`
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struct tag to override struct field names:
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```go
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input := struct {
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Values map[string]interface{} `pointer:"embedded"`
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}{
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Values: map[string]interface{}{
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"alice": 42,
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"bob": []interface{}{
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map[string]interface{}{
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"name": "Bob",
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},
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},
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},
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}
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value, err := Get(input, "/embedded/bob/0/name")
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if err != nil {
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panic(err)
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}
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fmt.Printf("%s", value)
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// Output:
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// Bob
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```
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