using Nlog and writing to file as json

As of the release of NLog 4.0.0 it is possible to use a layout that renders events as structured JSON documents.

Example taken from NLog project site:

<target name="jsonFile" xsi:type="File" fileName="${logFileNamePrefix}.json">    <layout xsi:type="JsonLayout">        <attribute name="time" layout="${longdate}" />        <attribute name="level" layout="${level:upperCase=true}"/>        <attribute name="message" layout="${message}" />    </layout></target>

Edit:You can also create it in code.

Here is the link to the specific part of documentation.

And here the copied example:

var jsonLayout = new JsonLayout{    Attributes =    {        new JsonAttribute("type", "${exception:format=Type}"),        new JsonAttribute("message", "${exception:format=Message}"),        new JsonAttribute("innerException", new JsonLayout        {            Attributes =            {                new JsonAttribute("type", "${exception:format=:innerFormat=Type:MaxInnerExceptionLevel=1:InnerExceptionSeparator=}"),                new JsonAttribute("message", "${exception:format=:innerFormat=Message:MaxInnerExceptionLevel=1:InnerExceptionSeparator=}"),            }        },        //don't escape layout        false)    }};

For more info read the docs.

As per NLog documentation: json-encode will only escape output of another layout using JSON rules. It will not "convert" the output to JSON. You'll have to do that yourself.

'{ "date":"${longdate}","level":"${level}","message":${message}}'

Take a look at this question for more details.