# Your First Template
Build a complete, realistic template from scratch.
## Project: User Profile Page
We'll create a user profile page template that displays user information with conditional sections.
## Step 1: Define Your Context
First, gather the data you want to display:
```elixir
context = %{
"user" => %{
"name" => "Alice Johnson",
"email" => "alice@example.com",
"role" => "admin",
"active" => true,
"joined_date" => "2023-01-15",
"profile" => %{
"bio" => "Passionate about Elixir and functional programming",
"location" => "San Francisco, CA",
"website" => "https://alice.dev"
}
},
"company" => %{
"name" => "Tech Startup Inc",
"industry" => "Software Development"
},
"projects" => [
%{"name" => "Phoenix API", "status" => "active"},
%{"name" => "Elixir Utilities", "status" => "active"},
%{"name" => "Old Project", "status" => "archived"}
]
}
```
## Step 2: Write the Template
Create a template that renders the profile:
```elixir
template = """
# {{ user.name }}
**Role:** {{ user.role | capitalize }}
**Email:** {{ user.email }}
**Status:** {% if user.active %}Active{% else %}Inactive{% endif %}
**Member Since:** {{ user.joined_date }}
## Bio
{{ user.profile.bio }}
## Contact Information
- **Location:** {{ user.profile.location }}
- **Website:** {{ user.profile.website }}
- **Company:** {{ company.name }} ({{ company.industry }})
## Projects ({{ projects | length }})
{% for project in projects %}
- **{{ project.name }}** - {{ project.status | capitalize }}
{% endfor %}
{% if user.role == "admin" %}
## Admin Section
You have administrative privileges in this system.
### Quick Actions
- Manage Users
- System Settings
- View Logs
{% endif %}
"""
```
## Step 3: Render the Template
```elixir
{:ok, result} = Mau.render(template, context)
IO.puts(result)
```
## Expected Output
```
# Alice Johnson
**Role:** Admin
**Email:** alice@example.com
**Status:** Active
**Member Since:** 2023-01-15
## Bio
Passionate about Elixir and functional programming
## Contact Information
- **Location:** San Francisco, CA
- **Website:** https://alice.dev
- **Company:** Tech Startup Inc (Software Development)
## Projects (3)
- **Phoenix API** - Active
- **Elixir Utilities** - Active
- **Old Project** - Archived
## Admin Section
You have administrative privileges in this system.
### Quick Actions
- Manage Users
- System Settings
- View Logs
```
## Walkthrough: What's Happening
### 1. Simple Interpolation
```
{{ user.name }} → "Alice Johnson"
```
Access nested properties with dot notation.
### 2. Filters
```
{{ user.role | capitalize }} → "Admin"
```
Transforms the value before display.
### 3. Conditionals
```
{% if user.active %}Active{% else %}Inactive{% endif %}
```
Renders different text based on conditions.
### 4. List Length
```
{{ projects | length }} → "3"
```
Count items in a collection.
### 5. Loops
```
{% for project in projects %}
- **{{ project.name }}** - {{ project.status | capitalize }}
{% endfor %}
```
Iterates through each item in the list.
### 6. Role-Based Sections
```
{% if user.role == "admin" %}
{# Admin content #}
{% endif %}
```
Show different content based on user role.
## Variations and Exercises
### Exercise 1: Add Member Status Badge
Modify the status line to show different badges:
```elixir
**Status:**
{% if user.active %}
🟢 Active
{% else %}
🔴 Inactive
{% endif %}
```
### Exercise 2: Filter Active Projects
Show only active projects:
```elixir
## Active Projects
{% for project in projects %}
{% if project.status == "active" %}
- {{ project.name }}
{% endif %}
{% endfor %}
```
### Exercise 3: Add Last Login
Add to context:
```elixir
context = %{
# ... existing data
"last_login" => "2024-01-29T14:30:00Z"
}
```
Then in template:
```elixir
**Last Login:** {{ last_login }}
```
### Exercise 4: Role-Based Menu
```elixir
{% if user.role == "admin" %}
[Admin Dashboard]
{% elsif user.role == "moderator" %}
[Moderation Panel]
{% else %}
[User Settings]
{% endif %}
```
## Common Patterns
### 1. Conditional Rendering
```elixir
{% if user.profile.bio %}
<div class="bio">{{ user.profile.bio }}</div>
{% endif %}
```
This checks if bio exists before showing it.
### 2. List with Fallback
```elixir
{% if projects %}
{% for project in projects %}
- {{ project.name }}
{% endfor %}
{% else %}
No projects yet
{% endif %}
```
### 3. Formatted Lists
```elixir
{% for project in projects %}
{% if forloop.first %}(1){% else %}, ({{ forloop.index }}){% endif %} {{ project.name }}
{% endfor %}
```
Output: `(1) Phoenix API, (2) Elixir Utilities, (3) Old Project`
### 4. Empty vs Populated
```elixir
{% if user.projects %}
Projects: {{ user.projects | join(", ") }}
{% else %}
No projects
{% endif %}
```
## Debugging Tips
### Check Your Context
Print context to verify data structure:
```elixir
IO.inspect(context, pretty: true)
```
### Test Small Pieces
Before building the full template, test individual expressions:
```elixir
Mau.render("{{ user.name }}", context)
Mau.render("{{ user.role | capitalize }}", context)
```
### Handle Missing Data
Always check if data exists before accessing it:
```elixir
{% if user.profile %}
Bio: {{ user.profile.bio }}
{% endif %}
```
### Preview Output
Render to a temporary file and check formatting:
```elixir
{:ok, result} = Mau.render(template, context)
File.write!("preview.txt", result)
```
## Next Steps
Now that you understand the basics, explore more advanced features:
- [Filters Guide](../guides/filters.md) - More powerful filters
- [Control Flow Guide](../guides/control-flow.md) - Advanced conditionals
- [Map Directives Guide](../guides/map-rendering.md) - Transform nested data
- [Report Generation Example](../examples/report-generation.md) - Real-world use cases
## Key Takeaways
✅ Templates combine text, variables, and logic
✅ Use `{{ }}` for dynamic content
✅ Use `{% %}` for logic (if, for)
✅ Chain filters with `|` to transform data
✅ Conditionals show/hide content
✅ Loops iterate over collections
✅ Always handle missing or empty data
You're ready to build templates! Start with simple examples and gradually add complexity.