README.md
1# hashstructure [](https://godoc.org/github.com/mitchellh/hashstructure)
2
3hashstructure is a Go library for creating a unique hash value
4for arbitrary values in Go.
5
6This can be used to key values in a hash (for use in a map, set, etc.)
7that are complex. The most common use case is comparing two values without
8sending data across the network, caching values locally (de-dup), and so on.
9
10## Features
11
12 * Hash any arbitrary Go value, including complex types.
13
14 * Tag a struct field to ignore it and not affect the hash value.
15
16 * Tag a slice type struct field to treat it as a set where ordering
17 doesn't affect the hash code but the field itself is still taken into
18 account to create the hash value.
19
20 * Optionally specify a custom hash function to optimize for speed, collision
21 avoidance for your data set, etc.
22
23 * Optionally hash the output of `.String()` on structs that implement fmt.Stringer,
24 allowing effective hashing of time.Time
25
26## Installation
27
28Standard `go get`:
29
30```
31$ go get github.com/mitchellh/hashstructure
32```
33
34## Usage & Example
35
36For usage and examples see the [Godoc](http://godoc.org/github.com/mitchellh/hashstructure).
37
38A quick code example is shown below:
39
40```go
41type ComplexStruct struct {
42 Name string
43 Age uint
44 Metadata map[string]interface{}
45}
46
47v := ComplexStruct{
48 Name: "mitchellh",
49 Age: 64,
50 Metadata: map[string]interface{}{
51 "car": true,
52 "location": "California",
53 "siblings": []string{"Bob", "John"},
54 },
55}
56
57hash, err := hashstructure.Hash(v, nil)
58if err != nil {
59 panic(err)
60}
61
62fmt.Printf("%d", hash)
63// Output:
64// 2307517237273902113
65```
66
){kind=link}