(window.webpackJsonp=window.webpackJsonp||[]).push([[109],{631:function(t,e,a){"use strict";a.r(e);var s=a(56),n=Object(s.a)({},(function(){var t=this,e=t.$createElement,a=t._self._c||e;return a("ContentSlotsDistributor",{attrs:{"slot-key":t.$parent.slotKey}},[a("h1",{attrs:{id:"jinja2-environment-and-context"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#jinja2-environment-and-context"}},[t._v("#")]),t._v(" Jinja2 Environment and Context")]),t._v(" "),a("p",[t._v("The Environment and Context are two key parts of how Jinja evaluates templates.")]),t._v(" "),a("p",[t._v("The Environment contains things like the available "),a("strong",[t._v("filters")]),t._v(", "),a("strong",[t._v("configuration")]),t._v(", or "),a("strong",[t._v("tests")]),t._v(" (and more). The Context contains the variables that will be available in the rendered template, as well as any exported variables from evaluating the template (such as macros).")]),t._v(" "),a("p",[t._v("Something important to note is that if we render one template and pass it a Context, but that template tries to import something from another, the latter won't have access to the Context. It will have access to the Environment though. 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Similarly, we can also tell Flask to add values to the Context through a few other means.")]),t._v(" "),a("p",[t._v("In addition, both Flask"),a("sup",{staticClass:"footnote-ref"},[a("a",{attrs:{href:"#fn1",id:"fnref1"}},[t._v("[1]")])]),t._v(" and Jinja2 provide values that are included in the Environment's "),a("code",[t._v("filters")]),a("sup",{staticClass:"footnote-ref"},[a("a",{attrs:{href:"#fn2",id:"fnref2"}},[t._v("[2]")])]),t._v(" and "),a("code",[t._v("tests")]),a("sup",{staticClass:"footnote-ref"},[a("a",{attrs:{href:"#fn3",id:"fnref3"}},[t._v("[3]")])]),t._v(" by default.")]),t._v(" "),a("p",[t._v("Flask also adds some values to the context that is passed to every rendered template as well.")]),t._v(" "),a("p",[t._v("Jinja2 provides some builtin functions"),a("sup",{staticClass:"footnote-ref"},[a("a",{attrs:{href:"#fn4",id:"fnref4"}},[t._v("[4]")])]),t._v(" which are part of the Environment, and are global.")]),t._v(" "),a("h2",{attrs:{id:"flask-context-values"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#flask-context-values"}},[t._v("#")]),t._v(" Flask context values")]),t._v(" "),a("p",[t._v("When we call "),a("code",[t._v("render_template")]),t._v(" in a Flask app, Flask passes the following values to the Context of the rendered template:")]),t._v(" "),a("ul",[a("li",[a("code",[t._v("config")]),t._v(": the current configuration object of our Flask app, "),a("code",[t._v("flask.config")]),t._v(".")]),t._v(" "),a("li",[a("code",[t._v("url_for()")]),t._v(": a function used to generate URLs given a Flask endpoint function name.")]),t._v(" "),a("li",[a("code",[t._v("get_flashed_messages()")]),t._v(": a function used to retrieve the messages that have been stored in the flashed messages stack.")])]),t._v(" "),a("p",[t._v("Flask will also add the following, if the template is rendered with an active request context (i.e. within a Flask endpoint):")]),t._v(" "),a("ul",[a("li",[a("code",[t._v("request")]),t._v(": the current request object, "),a("code",[t._v("flask.request")]),t._v(".")]),t._v(" "),a("li",[a("code",[t._v("session")]),t._v(": the current session object, "),a("code",[t._v("flask.session")]),t._v(".")]),t._v(" "),a("li",[a("code",[t._v("g")]),t._v(": the request-bound object for global variables, "),a("code",[t._v("flask.g")]),t._v(".")])]),t._v(" "),a("p",[t._v("It's important to note that these are in the Context, and not in the Environment. 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