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本文次要钻研一下zerolog的Formatter

Formatter

github.com/rs/zerolog@v1.20.0/console.go

// Formatter transforms the input into a formatted string.type Formatter func(interface{}) string
Formatter接口定义了一个func用于将interface{}转换为string

ConsoleWriter

github.com/rs/zerolog@v1.20.0/console.go

type ConsoleWriter struct {    // Out is the output destination.    Out io.Writer    // NoColor disables the colorized output.    NoColor bool    // TimeFormat specifies the format for timestamp in output.    TimeFormat string    // PartsOrder defines the order of parts in output.    PartsOrder []string    FormatTimestamp     Formatter    FormatLevel         Formatter    FormatCaller        Formatter    FormatMessage       Formatter    FormatFieldName     Formatter    FormatFieldValue    Formatter    FormatErrFieldName  Formatter    FormatErrFieldValue Formatter}
ConsoleWriter定义了TimeFormat、FormatTimestamp、FormatLevel、FormatCaller、FormatMessage、FormatFieldName、FormatFieldValue、FormatErrFieldName、FormatErrFieldValue属性

writePart

github.com/rs/zerolog@v1.20.0/console.go

// writePart appends a formatted part to buf.func (w ConsoleWriter) writePart(buf *bytes.Buffer, evt map[string]interface{}, p string) {    var f Formatter    switch p {    case LevelFieldName:        if w.FormatLevel == nil {            f = consoleDefaultFormatLevel(w.NoColor)        } else {            f = w.FormatLevel        }    case TimestampFieldName:        if w.FormatTimestamp == nil {            f = consoleDefaultFormatTimestamp(w.TimeFormat, w.NoColor)        } else {            f = w.FormatTimestamp        }    case MessageFieldName:        if w.FormatMessage == nil {            f = consoleDefaultFormatMessage        } else {            f = w.FormatMessage        }    case CallerFieldName:        if w.FormatCaller == nil {            f = consoleDefaultFormatCaller(w.NoColor)        } else {            f = w.FormatCaller        }    default:        if w.FormatFieldValue == nil {            f = consoleDefaultFormatFieldValue        } else {            f = w.FormatFieldValue        }    }    var s = f(evt[p])    if len(s) > 0 {        buf.WriteString(s)        if p != w.PartsOrder[len(w.PartsOrder)-1] { // Skip space for last part            buf.WriteByte(' ')        }    }}
writePart办法针对不同的field来取不同的Formatter，而后执行Formatter获取string，最初通过buf.WriteString(s)写入；如果FormatTimestamp没有设置，则取TimeFormat创立Formatter

实例

func formatDemo() {    output := zerolog.ConsoleWriter{Out: os.Stdout, TimeFormat: time.RFC3339}    output.FormatLevel = func(i interface{}) string {        return strings.ToUpper(fmt.Sprintf("| %-6s|", i))    }    output.FormatMessage = func(i interface{}) string {        return fmt.Sprintf("***%s****", i)    }    output.FormatFieldName = func(i interface{}) string {        return fmt.Sprintf("%s:", i)    }    output.FormatFieldValue = func(i interface{}) string {        return strings.ToUpper(fmt.Sprintf("%s", i))    }    log := zerolog.New(output).With().Timestamp().Logger()    log.Info().Str("foo", "bar").Msg("Hello World")}

输入

2021-01-06T23:16:42+08:00 | INFO  | ***Hello World**** foo:BAR

小结

zerolog的ConsoleWriter定义了Formatter用于自定义输入格局，如果FormatTimestamp没有设置，则取TimeFormat创立Formatter。

doc

  • zerolog