go-drill

README

Drill

This is a simple library to access the values of possibly nested structs with the well known dotted notation from JSON.

Design

Take for example the following nested structures:

type Container struct {
    A TypeA `json:"a"`
}

type TypeA struct {
    B TypeB `json:"b"`
}

type TypeB struct {
    C string `json:"c"`
}

The above might also have been references, maps (with string keys), arrays or slices. Take a look at the tests for more cases.

This library exposes a function to access the nested fields in dotted notation (for example "a.b.c"): Get. It accepts interface{} and returns a tuple (interface{}, error), so it is the caller's responsibility to check for errors and to cast the result in the appropriate type. If, at whichever level, one of the keys in the chain is missing, the Get returns ErrKeyNotFound.

From the example above

test := Container{A: A{B: B{C: "hi!"}}}
ret, err := Get(test, "a.b.c") // the error is nil
value := ret.(string) // this is "hi!"
ret, err := Get(test, "a.d") // this returns a nil interface and ErrKeyNotFound

This version is compatible with go<1.18. There is also a generics-based implementation tagged as v2.

Licence

This library is released in public domain. See LICENSE.