Error Handling

GoFr provides a structured error handling approach to simplify error management in your applications. The errors package in GoFr provides functionality for handling errors in GoFr applications. It includes predefined HTTP and database errors, as well as the ability to create custom errors with additional context.

Pre-defined HTTP Errors

GoFr's http package offers several predefined error types to represent common HTTP error scenarios. These errors automatically handle HTTP status code selection. These include:

{% table %}

• Error Type
• Description
• Status Code

• ErrorInvalidParam
• Represents an error due to an invalid parameter
• 400 (Bad Request)

• ErrorMissingParam
• Represents an error due to a missing parameter
• 400 (Bad Request)

• ErrorEntityNotFound
• Represents an error due to a not found entity
• 404 (Not Found)

• ErrorEntityAlreadyExist
• Represents an error due to creation of duplicate entity
• 409 (Conflict)

• ErrorInvalidRoute
• Represents an error for invalid route
• 404 (Not Found)

• ErrorRequestTimeout
• Represents an error for request which timed out
• 408 (Request Timeout)

• ErrorPanicRecovery
• Represents an error for request which panicked
• 500 (Internal Server Error)

{% /table %}

Usage:

To use the predefined HTTP errors, users need to import the GoFr http package and can simply call them:

import "gofr.dev/pkg/gofr/http"

err := http.ErrorMissingParam{Params: []string{"id"}}

Database Errors

Database errors in GoFr, represented in the datasource package, encapsulate errors related to database operations such as database connection, query failure, availability etc. The ErrorDB struct can be used to populate error as well as any custom message to it. Status Code: 500 (Internal Server Error)

Usage:

import "gofr.dev/pkg/gofr/datasource"

// Creating a custom error wrapped in  underlying error for database operations
dbErr := datasource.ErrorDB{Err: err, Message: "error from sql db"}

// Adding stack trace to the error
dbErr = dbErr.WithStack()

// Creating a custom error only with error message and no underlying error.
dbErr2 := datasource.ErrorDB{Message : "database connection timed out!"}

Custom Errors

GoFr's error structs implements an interface with Error() string and StatusCode() int methods, users can override the status code by implementing it for their custom error.

Users can optionally define a log level for your error with the LogLevel() logging.Level methods

Usage:

type customError struct {
    error string
}

func (c customError) Error() string {
    return fmt.Sprintf("custom error: %s", c.error)
}

func (c customError) StatusCode() int {
    return http.StatusMethodNotAllowed
}

func (c customError) LogLevel() logging.Level {
    return logging.WARN
}

Extended Error Responses

For RFC 9457 style error responses with additional fields, implement the ResponseMarshaller interface:

type ResponseMarshaller interface {
    Response() map[string]any
}

Usage:

type ValidationError struct {
    Field   string
    Message string
    Code    int
}

func (e ValidationError) Error() string    { return e.Message }
func (e ValidationError) StatusCode() int  { return e.Code }

func (e ValidationError) Response() map[string]any {
    return map[string]any{
        "field":   e.Field,
        "type":    "validation_error",
        "details": "Invalid input format",
    }
}

[!NOTE] The message field is automatically populated from the Error() method. Custom fields with the name "message" in the Response() map should not be used as they will be ignored in favor of the Error() value.