From 868b1c9d7ce0c2bcd053cec03d4bced543a19562 Mon Sep 17 00:00:00 2001 From: medusa Date: Sat, 1 Jun 2024 06:15:49 +0000 Subject: [PATCH] Add tech_docs/go_templates.md --- tech_docs/go_templates.md | 234 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 234 insertions(+) create mode 100644 tech_docs/go_templates.md diff --git a/tech_docs/go_templates.md b/tech_docs/go_templates.md new file mode 100644 index 0000000..6ef2adc --- /dev/null +++ b/tech_docs/go_templates.md @@ -0,0 +1,234 @@ +Sure! Let's break down the concept of actions in Go templates, represented by `{{ ... }}`, with examples for each type: variables, function calls, loops, conditionals, and more. + +### 1. Variables + +In Go templates, variables are placeholders that get replaced with actual data when the template is rendered. The data is typically passed to the template from the Go code. + +#### Example: +```go +{{ .Title }} +``` +Here, `{{ .Title }}` will be replaced by the value of the `Title` field in the data passed to the template. + +#### Go Code: +```go +data := struct { + Title string +}{ + Title: "Welcome to My Website", +} + +tmpl.Execute(w, data) +``` + +#### Template: +```html + + + + {{ .Title }} + + +

{{ .Title }}

+ + +``` + +### 2. Function Calls + +Go templates allow you to call functions to process data before rendering it. Built-in functions can be used directly in the template. + +#### Example: +```go +{{ .Date | dateFormat "2006-01-02" }} +``` +Here, `{{ .Date | dateFormat "2006-01-02" }}` formats the date using the `dateFormat` function. + +#### Go Code: +```go +data := struct { + Date time.Time +}{ + Date: time.Now(), +} + +tmpl.Execute(w, data) +``` + +#### Template: +```html + + + + Date Example + + +

{{ .Date | dateFormat "2006-01-02" }}

+ + +``` + +### 3. Loops + +Loops allow you to iterate over collections like arrays or slices. + +#### Example: +```go +{{ range .Items }} +
  • {{ . }}
    • +{{ end }} +``` +Here, `{{ range .Items }}` loops through each item in the `Items` collection. + +#### Go Code: +```go +data := struct { + Items []string +}{ + Items: []string{"Item 1", "Item 2", "Item 3"}, +} + +tmpl.Execute(w, data) +``` + +#### Template: +```html + + + + Loop Example + + + + + +``` + +### 4. Conditionals + +Conditionals are used to include or exclude parts of the template based on certain conditions. + +#### Example: +```go +{{ if .IsAdmin }} +

    Welcome, admin!

    +{{ else }} +

    Welcome, user!

    +{{ end }} +``` +Here, `{{ if .IsAdmin }}` checks if the `IsAdmin` variable is true. + +#### Go Code: +```go +data := struct { + IsAdmin bool +}{ + IsAdmin: true, +} + +tmpl.Execute(w, data) +``` + +#### Template: +```html + + + + Conditional Example + + + {{ if .IsAdmin }} +

    Welcome, admin!

    + {{ else }} +

    Welcome, user!

    + {{ end }} + + +``` + +### 5. Pipelines + +Pipelines allow you to chain multiple operations together. Each operation's output becomes the input for the next operation. + +#### Example: +```go +{{ .Price | multiply 1.1 | printf "%.2f" }} +``` +Here, `{{ .Price | multiply 1.1 | printf "%.2f" }}` multiplies `Price` by `1.1` and then formats it to two decimal places. + +#### Go Code: +```go +data := struct { + Price float64 +}{ + Price: 100.0, +} + +tmpl.Execute(w, data) +``` + +#### Template: +```html + + + + Pipeline Example + + +

    Price: ${{ .Price | multiply 1.1 | printf "%.2f" }}

    + + +``` + +### 6. Custom Functions + +You can define custom functions in Go and pass them to the template. + +#### Example: +Define a custom function to multiply a number: + +```go +func multiply(a, b float64) float64 { + return a * b +} +``` + +#### Go Code: +```go +func multiply(a, b float64) float64 { + return a * b +} + +func main() { + tmpl := template.New("example").Funcs(template.FuncMap{ + "multiply": multiply, + }) + + tmpl, _ = tmpl.Parse(` + + + + Custom Function Example + + +

    Price: ${{ .Price | multiply 1.1 }}

    + + `) + + data := struct { + Price float64 + }{ + Price: 100.0, + } + + tmpl.Execute(os.Stdout, data) +} +``` + +### Conclusion + +Go templates use `{{ ... }}` to perform various actions, including accessing variables, calling functions, iterating over collections, and evaluating conditions. This flexibility allows you to create dynamic, data-driven content easily. Understanding these actions helps you utilize the full power of Go templates effectively. \ No newline at end of file