在Nunjucks中测试字典是否有关键字

{
  "user": {
    "name": "John Doe",
    "email": "john.doe@example.com"
  }
}

{% set user = {
    "name": "John Doe",
    "email": "john.doe@example.com"
} %}

{% if 'name' in user %}
    <p>Name: {{ user.name }}</p>
{% else %}
    <p>Name is not available.</p>
{% endif %}

{% if 'email' in user %}
    <p>Email: {{ user.email }}</p>
{% else %}
    <p>Email is not available.</p>
{% endif %}

{% if 'age' in user %}
    <p>Age: {{ user.age }}</p>
{% else %}
    <p>Age is not available.</p>
{% endif %}

<p>Name: John Doe</p>
<p>Email: john.doe@example.com</p>
<p>Age is not available.</p>

const express = require('express');
const nunjucks = require('nunjucks');

const app = express();
nunjucks.configure('views', {
    autoescape: true,
    express: app
});

app.get('/', (req, res) => {
    const user = {
        name: "John Doe",
        email: "john.doe@example.com"
    };
    res.render('index.njk', { user });
});

app.listen(3000, () => {
    console.log('Server is running on http://localhost:3000');
});

{% if 'name' in user %}
    <p>Name: {{ user.name }}</p>
{% else %}
    <p>Name is not available.</p>
{% endif %}

{% if 'email' in user %}
    <p>Email: {{ user.email }}</p>
{% else %}
    <p>Email is not available.</p>
{% endif %}

{% if 'age' in user %}
    <p>Age: {{ user.age }}</p>
{% else %}
    <p>Age is not available.</p>
{% endif %}