murex Shell Docs

API Reference: Unmarshal()

Converts a structured file format into structured memory

Description

This is a function you would write when programming a murex data-type. The unmarshal function takes in a byte slice and returns a Go (golang) type or struct or an error.

This unmarshaller is then registered to murex inside an init() function and murex builtins can use that unmarshaller via the UnmarshalData() API.

Usage

Registering unmarshal (for writing builtin data-types)

// To avoid data races, this should only happen inside func init()
lang.Unmarshallers["json"] = unmarshal

Using an existing unmarshaller (eg inside a builtin command)

// See documentation on lang.UnmarshalData for more details
v, err := lang.UnmarshalData(p *lang.Process, dataType string)

Examples

Defining a marshaller for a murex data-type

package example

import (
    "encoding/json"

    "github.com/lmorg/murex/lang"
)

func init() {
    // Register data-type
    lang.Unmarshallers["example"] = unmarshal
}

// Describe unmarshaller
func unmarshal(p *lang.Process) (interface{}, error) {
    // Read data from STDIN. Because JSON expects closing tokens, we should
    // read the entire stream before unmarshalling it. For formats like CSV or
    // jsonlines which are more line based, we might want to read STDIN line by
    // line. However given there is just one data return, you still effectively
    // head to read the entire file before returning the structure. There are
    // other APIs for iterative returns for streaming data - more akin to the
    // traditional way UNIX pipes would work.
    b, err := p.Stdin.ReadAll()
    if err != nil {
        return nil, err
    }

    var v interface{}
    err = json.Unmarshal(b, &v)

    // Return the Go data structure or error
    return v, err
}

Parameters

  1. *lang.Process: Process's runtime state. Typically expressed as the variable p

See Also

This site is rebuilt weekly, the content is automatically generated from murex's source code. Last built on Mon Aug 3 06:12:53 UTC 2020 against commit 2557f7c2557f7cc7535c452c21d89164bd38ed8996f02fd. Downloadable murex binaries are also built weekly. Current version is 0.52.2000 BETA which has been verified against tests.