gin-error-handler/middleware.go

package handler

import (
	"errors"

	rErrors "codeberg.org/danjones000/responsable-errors"
	"github.com/gin-gonic/gin"
)

// Returns a gin middleware which writes a response with the error in the context.
func ErrorMiddleware(opts ...Option) gin.HandlerFunc {
	conf := config{}
	for _, opt := range opts {
		conf = opt(conf)
	}

	if len(conf.transformers) == 0 {
		conf.transformers = []Transformer{ginTransformer}
	}

	return func(c *gin.Context) {
		c.Next()
		err := c.Errors.Last()
		if err == nil {
			return
		}

		var re rErrors.ResponsableError

		errors.As(err, &re)
		// If we have at least one that's a ResponsableError, we should use it
		for _, err = range c.Errors {
			if re != nil {
				break
			}
			errors.As(err, &re)
		}

		// Next, let's check our transformers
		for _, trans := range conf.transformers {
			if re != nil {
				break
			}
			re = trans(err)
		}

		// Still couldn't find one, so it's a 500
		if re == nil {
			re = rErrors.NewInternalError("%w", err)
		}

		for _, logger := range conf.loggers {
			logger(c, re)
		}

		c.Set("rendered_error", re)

		// @todo check a response hasn't already been sent
		c.JSON(re.Status(), re)
	}
}