Hi.

Thanks for the great lib.

I wanted to ask: This lib add error tag on span on every error, even for ErrRecordNotFound. But ErrRecordNotFound it's not an error (from my point of view).

Maybe need to add Option which will allow to skip error tagging for some errors?

Describe the feature

Pass a tracker instead of global one

Motivation

I want use other ServiceName of tracker like "mysql" "postgres"

func main() {
	bootTracerBasedJaeger()

	db, _ := gorm.Open(mysql.Open("DSN"))

	db.Use(gormopentracing.New())

	span := opentracing.StartSpan("gorm")
	defer span.Finish()

	ctx := opentracing.ContextWithSpan(context.Background(), span)

	sess := db.WithContext(ctx)

	account := &Account{}

	sess.First(&account, 1)
}

// Reporting span 35bb47763bfe8a72:35bb47763bfe8a72:0000000000000000:1

But nothing can be searched in jaeger UI.

• [x] Do only one thing
• [x] Non breaking API changes
• [x] Tested

What did this pull request do?

Adds options for operation names:

• WithCreateOpName
• WithUpdateOpName
• WithQueryOpName
• WithDeleteOpName
• WithRowOpName
• WithRawOpName

• [x] Do only one thing
• [x] Nonbreaking API changes
• [x] Tested

What did this pull request do?

• provide the WithTracer API to customize tracer
• use opt options instead of logResult and tracer property in opentracingPlugin
• define extractAfter and injectBefore into opentracingPlugin methods, and rename helper.go as opentracing_helper.go

User Case Description

use customized tracer of DB operation rather than have to use global tracer.

• [x] Do only one thing
• [x] Non breaking API changes
• [x] Tested

What did this pull request do?

Exports applyOptions for consumption by applications. This is potentially useful for building a conditional/dynamic list of options, without having to call gormopentracing.New() in each of the conditionals. For example:

if condition {
      gormopentracing.New(
          gormopentracing.WithTracer(tracer),
          gormopentracing.WithSqlParameters(false),
          )
} else
      gormopentracing.New(
          gormopentracing.WithTracer(tracer),
          gormopentracing.WithSqlParameters(true),
          )
}

Becomes:

if condition {
          applyOpts := []gormopentracing.ApplyOpts {
              gormopentracing.WithTracer(tracer),
              gormopentracing.WithSqlParameters(false),
              // other opts
          }
} else
          applyOpts := []gormopentracing.ApplyOpts {
              gormopentracing.WithTracer(),
              gormopentracing.WithSqlParameters(true),
              // other opts
          }
}
gormopentracing.New(...applyOpts)

• [X] Do only one thing
• [X] Non breaking API changes
• [X] Tested

What did this pull request do?

This change adds flag that conditionally adds parameters to sql queries.

User Case Description

I don't want to expose sensitive data from sql queries to jeager through traces. That's why adding this flag would be really helpful to keep sql statements with placeholders instead of variables.

• [x] Do only one thing
• [x] Non breaking API changes
• [x] Tested

What did this pull request do?

update readme

User Case Description

describes how to specify the tracer to the opentracing plugin