Fielder

Fielder is a tool to generate Go code that extracts fields from a struct and transforms them into ENUM. Also, it adds useful types, methods and functions.

Motivation

When using ORM-s like gorm, go-pg, bun you have to pass column names as arguments of different methods. This is a pain to use raw strings for that, and it also might be a security risk. Much better to rely on ENUM which represents columns for a specific table.
Also, the generated field names can be used in combination with Golang reflection (FieldByName) for different purposes.

Features

The library provides the following features:

• Struct fields representation with ENUM.
• Different functions and methods to work with ENUM (validation, listing, conversion to string, etc).
• Tag-based field names extraction (regex can be used to extract a value from a tag).
• Embedded fields extraction.
• Fields excluding.
• Different formatting (camel, pascal, snake).
• Template overriding.

Installation

go install github.com/kpeu3i/[email protected]

Usage

Put the go:generate directive in the same package as the struct you want to generate. For example:

//go:generate fielder -type=UserAccount

package models
 
type UserAccount struct {
    FirstName string
    LastName  string
    Email     string
    Password  string
}

Then, run command bellow to generate the code:

$ go generate ./...

The following formatting strategies can be applied for the extracted field names (see format and tag_format flag):

• snake_case (e.g first_name)
• camel_case (e.g firstName)
• pascal_case (e.g FirstName)

For more details, check the examples folder in the project root.

The following CLI flags are allowed:

Usage of fielder:
  -embedded
    	Extract embedded fields (default false)
  -excluded string
    	Comma separated list of excluded fields (default "")
  -format string
    	Format of the generated type values extracted from the struct field (default "as_is")
  -output string
    	Set output filename (default "<src_dir>/<type>_fielder.go")
  -pkg string
    	Package name to extract type from (default ".")
  -suffix string
    	Suffix for the generated struct (default "Field")
  -tag string
    	Tag to extract field values from (default "")
  -tag_format string
    	Format of the generated type values extracted from the tag (default "as_is")
  -tag_regexp string
    	Regular expression to parse field value from a tag (default "")
  -tag_strict
    	Strict mode for tag parsing (returns error if tag is not found)
  -tpl string
    	Set template filename (default "")
  -type string
    	Type to extract fields from

Generated types, functions and methods

When Fielder is applied to a type, it will generate public functions/methods and types:

• Type <Type><Suffix> represents fields ENUM:
  • Method <Type><Suffix>::IsValid returns true if the value is a valid ENUM.
  • Method <Type><Suffix>::String returns the string representation of the value.
• Type <Type><Suffix>List represents collection of ENUM fields:
  • Method <Type><Suffix>List::Len returns the number of values in the collection.
  • Method <Type><Suffix>List::IsEmpty returns true if the collection is empty.
  • Method <Type><Suffix>List::Contains returns true if the collection contains the value.
  • Method <Type><Suffix>List::Equals returns true if the two collections are equal.
  • Method <Type><Suffix>List::Similar returns true if the two collections contain the same values.
  • Method <Type><Suffix>List::Add adds the values to the collection.
  • Method <Type><Suffix>List::AddIfNotContains adds the values to the collection if they are not already present.
  • Method <Type><Suffix>List::Remove removes the values from the collection.
  • Method <Type><Suffix>List::Clear clears the collection.
  • Method <Type><Suffix>List::Clone returns a pointer to a copy of the collection.
  • Method <Type><Suffix>List::Strings returns a slice with all the strings of the collection items.
• Functions:
  • <Type><Suffix>Values returns a slice with all the values of the ENUM.
  • <Type><Suffix>Strings returns a slice with all the strings of the ENUM.
  • New<Type><Suffix> returns a new collection with all the values of the ENUM.
  • New<Type><Suffix>With returns a new collection with the given values of the ENUM.

Inspiring projects

• enumer
• stringer