goError

goError is a simple and pluggable go package allows you to create and handle errors in golang more efficiently & gracefully, also allowing you to preserve the context of every error.

Why use this package?

• Plug and Play (compatible with existing go errors package)
• Allows you to specify error types
• Easy conversion of error into Map or JSON.
• Add context to error for passing the human readable error message to client side applications.
• Wrap and Unwrap error stack.

Documentation

Let's look at the some code snippets. But before this, make sure to download the package using

go get -v github.com/vasupal1996/goerror

and import the package as

import  (
    errors "github.com/vasupal1996/goerror"
)

Create error

Syntax:

New(message string, error_type Type) error

1. Create an error without error type

Example:

err := errors.New("error message", nil)
fmt.Println(err)
>> error message

Note: when you don't specify any error type NoType is set by default.

2. Create an error with error type

Example:

err :=  errors.New("error message", &errors.BadRequest)
fmt.Println(err)
>> error message

Add context to error

Syntax:

SetContext(error_object error, key string, value interface{}) error

Example:

err :=  errors.New("programmer friendly error message", nil)
err := errors.SetContext(err, "user-email", "email is missing")

---

err :=  errors.New("programmer friendly error message", nil)
err := errors.SetContext(err, "email", map[string]string{"email_domain": "invalid email domain", "email_local_part": "invalid local part (must start with `a` alphabet)"})

Get error context

Syntax:

GetContext(error_object error) map[string]interface{}

Example:

ctx :=  errors.GetContext(error)

Add/update error type

Syntax:

SetType(error_object error, type *Type) error

Example:

err :=  errors.SetType(err, &errors.NotFound)

---

var customErrorType errors.Type = "CustomErrorType"
err :=  errors.SetType(err, &customErrorType)

List of predefined error types:

 1. NoType
 2. BadRequest
 3. NotFound
 4. DBError
 5. Unauthorized
 6. PermissionDenied
 7. SomethingWentWrong

Get error type

Syntax:

GetType(error_object error) Type

Example:

errType :=  errors.GetType(err)

Create custom error type

Example:

var CustomErrorType errors.Type = "CustomErrorType"

Compare two errors (errors Is)

Syntax:

errors.Is(error_1 error, error_2 error) bool

Example:

err1 := errors.New("error1", nil)
err2 := errors.New("error2", nil)
isSame := errors.Is(err1, err2)

fmt.Println(isSame)
>>false

err3 := err1
isSame = errors.Is(err3, err1)

fmt.Println(isSame)
>>true

Compare error types (errors As)

Syntax:

errors.As(error_1 error, error_2 error) bool

Example:

err1 := errors.New("error1", nil)
err2 := errors.New("error2", nil)
isSameType := errors.As(err1, err2)

fmt.Println(isSameType)
>>true 
// Because of NoType (default)

err3 := errors.New("error2", &errors.BadRequest)
isSameType = errors.As(err3, err1)

fmt.Println(isSameType)
>>false

Convert error to Map

Syntax:

errors.Map(error_1 error) map[string]interface{}

Example:

err1 := errors.New("error1", nil)
errMap := errors.Map(err1)
fmt.Println(errMap)
>> map[message:error1 type:NoType]
err1 = errors.SetContext(err1, "email", "email not found")
errMap = errors.Map(err1)
fmt.Println(errMap)
>> map[field:email message:email not found type:NoType]

Convert error to JSON

Syntax:

errors.Map(error_1 error) map[string]interface{}

Example:

err1 := errors.New("error1", nil)
errJSON := errors.JSON(err1)

fmt.Println(string(errJSON))
>> {"message":"error1","type":"NoType"}

err1 = errors.SetContext(err1, "email", "email not found")
errJSON = errors.JSON(err1)

fmt.Println(string(errJSON))
>> {"field":"email","message":"email not found","type":"NoType"}