class Template

Library: JSON
Package: JSON
Header: Poco/JSON/Template.h


Template is a template engine which uses JSON as input for generating output. There are commands for looping over JSON arrays, include other templates, conditional output, etc.

All text is send to the outputstream. A command is placed between




These are the available commands:

<? echo query ?>

The result of the query is send to the output stream This command can also be written as NOT FOUND: query

<? if query ?> <? else ?> <? endif ?>

When the result of query is true, all the text between if and else (or endif when there is no else) is send to the output stream. When the result of query is false, all the text between else and endif is send to the output stream. An empty object, an empty array or a null value is considered as a false value. For numbers a zero is false. An empty String is also false.

<? ifexist query ?> <? else ?> <? endif ?>

This can be used to check the existence of the value. Use this for example when a zero value is ok (which returns false for NOT FOUND: if.

<? for variable query ?> <? endfor ?>

The result of the query must be an array. For each element in the array the text between for and endfor is send to the output stream. The active element is stored in the variable.

<? include "filename" ?>

Includes a template. When the filename is relative it will try to resolve the filename against the active template. When this file doesn't exist, it can still be found when the JSONTemplateCache is used.

A query is passed to Poco::JSON::Query to get the value.

Member Summary

Member Functions: parse, parseTime, render

Types Aliases


using Ptr = SharedPtr < Template >;




Creates a Template.


    const Path & templatePath

Creates a Template from the file with the given templatePath.


~Template virtual

virtual ~Template();

Destroys the Template.

Member Functions

parse inline

void parse();

Parse a template from a file.


void parse(
    const std::string & source

Parse a template from a string.


void parse(
    std::istream & in

Parse a template from an input stream.

parseTime inline

Timestamp parseTime() const;

Returns the time when the template was parsed.


void render(
    const Dynamic::Var & data,
    std::ostream & out
) const;

Renders the template and send the output to the stream.