Merge pull request #578 from adamchester/logging-output-template

Allow further customising the console output

Author: Henrik Feldt

examples/Example/Program.fs

@@ -17,7 +17,19 @@ open Suave.State.CookieStateStore
 let basicAuth =
   Authentication.authenticateBasic ((=) ("foo", "bar"))
 
-let logger = Targets.create Verbose [||]
+// This demonstrates how to customise the console logger output.
+// In most cases you wont need this. Instead you can use the more succinct: 
+// `let logger = Targets.create Verbose [||]`
+let loggingOptions =
+  { Literate.LiterateOptions.create() with
+      getLogLevelText = function Verbose->"V" | Debug->"D" | Info->"I" | Warn->"W" | Error->"E" | Fatal->"F" }
+
+let logger = LiterateConsoleTarget(
+                name = [|"Suave";"Examples";"Example"|],
+                minLevel = Verbose,
+                options = loggingOptions,
+                outputTemplate = "[{level}] {timestampUtc:o} {message} [{source}]{exceptions}"
+              ) :> Logger
 
 ///  With this workflow you can write WebParts like this
 let task : WebPart =

paket-files/logary/logary/src/Logary.Facade/Facade.fs

@@ -1,4 +1,4 @@
-/// The logging namespace, which contains the logging abstraction for this
+/// The logging namespace, which contains the logging abstraction for this
 /// library. See https://github.com/logary/logary for details. This module is
 /// completely stand-alone in that it has no external references and its adapter
 /// in Logary has been well tested.
@@ -600,6 +600,14 @@ module internal Formatting =
 
     exnExceptionParts @ errorsExceptionParts
 
+  let getLogLevelToken = function
+    | Verbose -> LevelVerbose
+    | Debug -> LevelDebug
+    | Info -> LevelInfo
+    | Warn -> LevelWarning
+    | Error -> LevelError
+    | Fatal -> LevelFatal
+
   /// Split a structured message up into theme-able parts (tokens), allowing the
   /// final output to display to a user with colours to enhance readability.
   let literateDefaultTokeniser (options : LiterateOptions) (message : Message) : (string * LiterateToken) list =
@@ -612,14 +620,6 @@ module internal Formatting =
 
     let themedExceptionParts = literateColouriseExceptions options message
 
-    let getLogLevelToken = function
-      | Verbose -> LevelVerbose
-      | Debug -> LevelDebug
-      | Info -> LevelInfo
-      | Warn -> LevelWarning
-      | Error -> LevelError
-      | Fatal -> LevelFatal
-
     [ "[", Punctuation
       formatLocalTime message.utcTicks
       " ", Subtext
@@ -684,6 +684,81 @@ module internal Formatting =
     formatExn message.fields +
     formatFields matchedFields message.fields
 
+/// Assists with controlling the output of the `LiterateConsoleTarget`.
+module internal LiterateFormatting =
+  open Literate
+  type TokenisedPart = string * LiterateToken
+  type LiterateTokeniser = LiterateOptions -> Message -> TokenisedPart list
+
+  type internal TemplateToken = TextToken of text:string | PropToken of name : string * format : string
+  let internal parseTemplate template =
+    let tokens = ResizeArray<TemplateToken>()
+    let foundText (text: string) = tokens.Add (TextToken text)
+    let foundProp (prop: FsMtParser.Property) = tokens.Add (PropToken (prop.name, prop.format))
+    FsMtParser.parseParts template foundText foundProp
+    tokens :> seq<TemplateToken>
+  
+  [<AutoOpen>]
+  module OutputTemplateTokenisers =
+
+    let tokeniseTimestamp format (options : LiterateOptions) (message : Message) = 
+      let localDateTimeOffset = DateTimeOffset(message.utcTicks, TimeSpan.Zero).ToLocalTime()
+      let formattedTimestamp = localDateTimeOffset.ToString(format, options.formatProvider)
+      seq { yield formattedTimestamp, Subtext }
+
+    let tokeniseTimestampUtc format (options : LiterateOptions) (message : Message) = 
+      let utcDateTimeOffset = DateTimeOffset(message.utcTicks, TimeSpan.Zero)
+      let formattedTimestamp = utcDateTimeOffset.ToString(format, options.formatProvider)
+      seq { yield formattedTimestamp, Subtext }
+
+    let tokeniseMissingField name format =
+      seq {
+        yield "{", Punctuation
+        yield name, MissingTemplateField
+        if not (String.IsNullOrEmpty format) then
+          yield ":", Punctuation
+          yield format, Subtext
+        yield "}", Punctuation }
+
+    let tokeniseLogLevel (options : LiterateOptions) (message : Message) =
+      seq { yield options.getLogLevelText message.level, Formatting.getLogLevelToken message.level }
+
+    let tokeniseSource (options : LiterateOptions) (message : Message) =
+      seq { yield (String.concat "." message.name), Subtext }
+
+    let tokeniseNewline (options : LiterateOptions) (message : Message) =
+      seq { yield Environment.NewLine, Text }
+
+    let tokeniseTab (options : LiterateOptions) (message : Message) =
+      seq { yield "\t", Text }
+
+  /// Creates a `LiterateTokeniser` function which can be passed to the `LiterateConsoleTarget`
+  /// constructor in order to customise how each log message is rendered. The default template
+  /// would be: `[{timestampLocal:HH:mm:ss} {level}] {message}{newline}{exceptions}`.
+  /// Available template fields are: `timestamp`, `timestampUtc`, `level`, `source`,
+  /// `newline`, `tab`, `message`, `exceptions`. Any misspelled or otheriwese invalid property
+  /// names will be treated as `LiterateToken.MissingTemplateField`. 
+  let tokeniserForOutputTemplate template : LiterateTokeniser =
+    let tokens = parseTemplate template
+    fun options message ->
+      seq {
+        for token in tokens do
+          match token with
+          | TextToken text -> yield text, LiterateToken.Punctuation
+          | PropToken (name, format) ->
+            match name with
+            | "timestamp" ->    yield! tokeniseTimestamp format options message
+            | "timestampUtc" -> yield! tokeniseTimestampUtc format options message
+            | "level" ->        yield! tokeniseLogLevel options message
+            | "source" ->       yield! tokeniseSource options message
+            | "newline" ->      yield! tokeniseNewline options message
+            | "tab" ->          yield! tokeniseTab options message
+            | "message" ->      yield! Formatting.literateFormatValue options message.fields message.value |> snd
+            | "exceptions" ->   yield! Formatting.literateColouriseExceptions options message
+            | _ ->              yield! tokeniseMissingField name format
+      }
+      |> Seq.toList
+
 /// Logs a line in a format that is great for human consumption,
 /// using console colours to enhance readability.
 /// Sample: [10:30:49 INF] User "AdamC" began the "checkout" process with 100 cart items
@@ -698,6 +773,15 @@ type LiterateConsoleTarget(name, minLevel, ?options, ?literateTokeniser, ?output
     |> List.map (fun (s, t) ->
       s, options.theme(t))
 
+  /// Creates the target with a custom output template. The default `outputTemplate`
+  /// is `[{timestampLocal:HH:mm:ss} {level}] {message}{exceptions}`.
+  /// Available template fields are: `timestamp`, `timestampUtc`, `level`, `source`,
+  /// `newline`, `tab`, `message`, `exceptions`. Any misspelled or otheriwese invalid property
+  /// names will be treated as `LiterateToken.MissingTemplateField`.
+  new (name, minLevel, outputTemplate, ?options, ?outputWriter, ?consoleSemaphore) =
+    let tokeniser = LiterateFormatting.tokeniserForOutputTemplate outputTemplate
+    LiterateConsoleTarget(name, minLevel, ?options=options, literateTokeniser=tokeniser, ?outputWriter=outputWriter, ?consoleSemaphore=consoleSemaphore)
+
   interface Logger with
     member x.name = name
     member x.logWithAck level msgFactory =

paket.dependencies

@@ -8,7 +8,7 @@ nuget DotLiquid
 nuget RazorEngine
 
 github haf/YoLo YoLo.fs
-github logary/logary src/Logary.Facade/Facade.fs
+github logary/logary:c70468f60602e1ab954a38e574b946d4ffbda11d src/Logary.Facade/Facade.fs
 
 group Build
   source https://nuget.org/api/v2

paket.lock

@@ -11,7 +11,7 @@ GITHUB
   remote: haf/YoLo
     YoLo.fs (76e16a4c9338c2f04cb067add0e3a33b42a0f396)
   remote: logary/logary
-    src/Logary.Facade/Facade.fs (8fe3fce3f7d2602f2a4dc27419edfbce09c28a82)
+    src/Logary.Facade/Facade.fs (c70468f60602e1ab954a38e574b946d4ffbda11d)
 GROUP Build
 NUGET
   remote: https://www.nuget.org/api/v2
@@ -196,7 +196,6 @@ NUGET
       System.AppContext (>= 4.1)
       System.Collections (>= 4.0.11)
       System.Collections.Concurrent (>= 4.0.12)
-      System.Collections.Immutable (>= 1.1.37)
       System.Collections.Immutable (>= 1.2)
       System.Console (>= 4.0)
       System.Diagnostics.Debug (>= 4.0.11)
@@ -210,7 +209,6 @@ NUGET
       System.Linq (>= 4.1)
       System.Linq.Expressions (>= 4.1)
       System.Reflection (>= 4.1)
-      System.Reflection.Metadata (>= 1.2)
       System.Reflection.Metadata (>= 1.3)
       System.Reflection.Primitives (>= 4.0.1)
       System.Resources.ResourceManager (>= 4.0.1)