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<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Go by Example မြန်မာဘာသာ: JSON</title>
<link rel=stylesheet href="site.css">
</head>
<script>
onkeydown = (e) => {
if (e.key == "ArrowLeft") {
window.location.href = 'regular-expressions';
}
if (e.key == "ArrowRight") {
window.location.href = 'xml';
}
}
</script>
<body>
<div class="example" id="json">
<h2><a href="./">Go by Example မြန်မာဘာသာ</a>: JSON</h2>
<table>
<tr>
<td class="docs">
<p>Go က JSON encoding နဲ့ decoding အတွက် built-in support ပေးထားပါတယ်။
built-in နဲ့ custom data type တွေကနေ JSON သို့၊ JSON ကနေ ပြန်ပြောင်းတာတွေ ပါဝင်ပါတယ်။</p>
</td>
<td class="code empty leading">
</td>
</tr>
<tr>
<td class="docs">
</td>
<td class="code leading">
<a href="https://go.dev/play/p/_aKnKrRgvTn"><img title="Run code" src="play.png" class="run" /></a><img title="Copy code" src="clipboard.png" class="copy" />
<pre class="chroma"><span class="kn">package</span> <span class="nx">main</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
</td>
<td class="code leading">
<pre class="chroma"><span class="kn">import</span> <span class="p">(</span>
<span class="s">"encoding/json"</span>
<span class="s">"fmt"</span>
<span class="s">"os"</span>
<span class="p">)</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>အောက်က struct နှစ်ခုကို custom type တွေရဲ့ encoding နဲ့ decoding ကို သရုပ်ပြဖို့ သုံးပါမယ်။</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="kd">type</span> <span class="nx">response1</span> <span class="kd">struct</span> <span class="p">{</span>
<span class="nx">Page</span> <span class="kt">int</span>
<span class="nx">Fruits</span> <span class="p">[]</span><span class="kt">string</span>
<span class="p">}</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>Export လုပ်ထားတဲ့ field တွေကိုပဲ JSON အဖြစ် encode/decode လုပ်ပါမယ်။
Field တွေကို export လုပ်ဖို့ စာလုံးအကြီးနဲ့ စရပါမယ်။</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="kd">type</span> <span class="nx">response2</span> <span class="kd">struct</span> <span class="p">{</span>
<span class="nx">Page</span> <span class="kt">int</span> <span class="s">`json:"page"`</span>
<span class="nx">Fruits</span> <span class="p">[]</span><span class="kt">string</span> <span class="s">`json:"fruits"`</span>
<span class="p">}</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
</td>
<td class="code leading">
<pre class="chroma"><span class="kd">func</span> <span class="nf">main</span><span class="p">()</span> <span class="p">{</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>ပထမဆုံး အခြေခံ data type တွေကို JSON string အဖြစ် encode လုပ်တာကို ကြည့်ကြရအောင်။
ဒီမှာ atomic value တွေအတွက် ဥပမာတချို့ ရှိပါတယ်။</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nx">bolB</span><span class="p">,</span> <span class="nx">_</span> <span class="o">:=</span> <span class="nx">json</span><span class="p">.</span><span class="nf">Marshal</span><span class="p">(</span><span class="kc">true</span><span class="p">)</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="nb">string</span><span class="p">(</span><span class="nx">bolB</span><span class="p">))</span>
<span class="nx">intB</span><span class="p">,</span> <span class="nx">_</span> <span class="o">:=</span> <span class="nx">json</span><span class="p">.</span><span class="nf">Marshal</span><span class="p">(</span><span class="mi">1</span><span class="p">)</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="nb">string</span><span class="p">(</span><span class="nx">intB</span><span class="p">))</span>
<span class="nx">fltB</span><span class="p">,</span> <span class="nx">_</span> <span class="o">:=</span> <span class="nx">json</span><span class="p">.</span><span class="nf">Marshal</span><span class="p">(</span><span class="mf">2.34</span><span class="p">)</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="nb">string</span><span class="p">(</span><span class="nx">fltB</span><span class="p">))</span>
<span class="nx">strB</span><span class="p">,</span> <span class="nx">_</span> <span class="o">:=</span> <span class="nx">json</span><span class="p">.</span><span class="nf">Marshal</span><span class="p">(</span><span class="s">"gopher"</span><span class="p">)</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="nb">string</span><span class="p">(</span><span class="nx">strB</span><span class="p">))</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>ဒီမှာတော့ slice တွေနဲ့ map တွေအတွက် ဥပမာတွေပါ။ သူတို့က
မျှော်လင့်ထားသလိုပဲ JSON array တွေနဲ့ object တွေအဖြစ် encode လုပ်ပါတယ်။</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nx">slcD</span> <span class="o">:=</span> <span class="p">[]</span><span class="kt">string</span><span class="p">{</span><span class="s">"apple"</span><span class="p">,</span> <span class="s">"peach"</span><span class="p">,</span> <span class="s">"pear"</span><span class="p">}</span>
<span class="nx">slcB</span><span class="p">,</span> <span class="nx">_</span> <span class="o">:=</span> <span class="nx">json</span><span class="p">.</span><span class="nf">Marshal</span><span class="p">(</span><span class="nx">slcD</span><span class="p">)</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="nb">string</span><span class="p">(</span><span class="nx">slcB</span><span class="p">))</span>
<span class="nx">mapD</span> <span class="o">:=</span> <span class="kd">map</span><span class="p">[</span><span class="kt">string</span><span class="p">]</span><span class="kt">int</span><span class="p">{</span><span class="s">"apple"</span><span class="p">:</span> <span class="mi">5</span><span class="p">,</span> <span class="s">"lettuce"</span><span class="p">:</span> <span class="mi">7</span><span class="p">}</span>
<span class="nx">mapB</span><span class="p">,</span> <span class="nx">_</span> <span class="o">:=</span> <span class="nx">json</span><span class="p">.</span><span class="nf">Marshal</span><span class="p">(</span><span class="nx">mapD</span><span class="p">)</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="nb">string</span><span class="p">(</span><span class="nx">mapB</span><span class="p">))</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>JSON package က သင့်ရဲ့ custom data type တွေကို အလိုအလျောက် encode လုပ်ပေးနိုင်ပါတယ်။
သူက encode လုပ်ထားတဲ့ output ထဲမှာ export လုပ်ထားတဲ့ field တွေကိုပဲ ထည့်သွင်းပြီး
ပုံမှန်အားဖြင့် အဲဒီနာမည်တွေကိုပဲ JSON key အဖြစ် သုံးပါတယ်။</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nx">res1D</span> <span class="o">:=</span> <span class="o">&</span><span class="nx">response1</span><span class="p">{</span>
<span class="nx">Page</span><span class="p">:</span> <span class="mi">1</span><span class="p">,</span>
<span class="nx">Fruits</span><span class="p">:</span> <span class="p">[]</span><span class="kt">string</span><span class="p">{</span><span class="s">"apple"</span><span class="p">,</span> <span class="s">"peach"</span><span class="p">,</span> <span class="s">"pear"</span><span class="p">}}</span>
<span class="nx">res1B</span><span class="p">,</span> <span class="nx">_</span> <span class="o">:=</span> <span class="nx">json</span><span class="p">.</span><span class="nf">Marshal</span><span class="p">(</span><span class="nx">res1D</span><span class="p">)</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="nb">string</span><span class="p">(</span><span class="nx">res1B</span><span class="p">))</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>Struct field ကြေညာချက်တွေမှာ tag တွေ သုံးပြီး encode လုပ်ထားတဲ့ JSON key နာမည်တွေကို
စိတ်ကြိုက်ပြောင်းလဲနိုင်ပါတယ်။ အဲဒီလို tag တွေရဲ့ ဥပမာကို အပေါ်က <code>response2</code> အဓိပ္ပာယ်ဖွင့်ဆိုချက်မှာ ကြည့်ပါ။</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nx">res2D</span> <span class="o">:=</span> <span class="o">&</span><span class="nx">response2</span><span class="p">{</span>
<span class="nx">Page</span><span class="p">:</span> <span class="mi">1</span><span class="p">,</span>
<span class="nx">Fruits</span><span class="p">:</span> <span class="p">[]</span><span class="kt">string</span><span class="p">{</span><span class="s">"apple"</span><span class="p">,</span> <span class="s">"peach"</span><span class="p">,</span> <span class="s">"pear"</span><span class="p">}}</span>
<span class="nx">res2B</span><span class="p">,</span> <span class="nx">_</span> <span class="o">:=</span> <span class="nx">json</span><span class="p">.</span><span class="nf">Marshal</span><span class="p">(</span><span class="nx">res2D</span><span class="p">)</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="nb">string</span><span class="p">(</span><span class="nx">res2B</span><span class="p">))</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>အခု JSON data ကို Go value တွေအဖြစ် decode လုပ်တာကို ကြည့်ကြရအောင်။
ဒီမှာ အထွေထွေသုံး data structure တစ်ခုအတွက် ဥပမာတစ်ခု ရှိပါတယ်။</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nx">byt</span> <span class="o">:=</span> <span class="p">[]</span><span class="nb">byte</span><span class="p">(</span><span class="s">`{"num":6.13,"strs":["a","b"]}`</span><span class="p">)</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>JSON package က decode လုပ်ထားတဲ့ data ကို ထည့်နိုင်မယ့် variable တစ်ခု ပေးဖို့ လိုပါတယ်။
ဒီ <code>map[string]interface{}</code> က string တွေကနေ မည်သည့် data type မဆိုကို ညွှန်းတဲ့ map တစ်ခုကို ကိုင်ထားပါလိမ့်မယ်။</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="kd">var</span> <span class="nx">dat</span> <span class="kd">map</span><span class="p">[</span><span class="kt">string</span><span class="p">]</span><span class="kd">interface</span><span class="p">{}</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>ဒါကတော့ တကယ့် decoding လုပ်တာပါ၊ ပြီးတော့ ဆက်စပ်နေတဲ့ error တွေကိုလည်း စစ်ဆေးပါတယ်။</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="k">if</span> <span class="nx">err</span> <span class="o">:=</span> <span class="nx">json</span><span class="p">.</span><span class="nf">Unmarshal</span><span class="p">(</span><span class="nx">byt</span><span class="p">,</span> <span class="o">&</span><span class="nx">dat</span><span class="p">);</span> <span class="nx">err</span> <span class="o">!=</span> <span class="kc">nil</span> <span class="p">{</span>
<span class="nb">panic</span><span class="p">(</span><span class="nx">err</span><span class="p">)</span>
<span class="p">}</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="nx">dat</span><span class="p">)</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>Decode လုပ်ထားတဲ့ map ထဲက တန်ဖိုးတွေကို သုံးဖို့ဆိုရင်
သူတို့ကို သင့်တော်တဲ့ type အဖြစ် ပြောင်းဖို့ လိုပါလိမ့်မယ်။
ဥပမာ ဒီမှာ <code>num</code> ထဲက တန်ဖိုးကို မျှော်လင့်ထားတဲ့ <code>float64</code> type အဖြစ် ပြောင်းပါတယ်။</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nx">num</span> <span class="o">:=</span> <span class="nx">dat</span><span class="p">[</span><span class="s">"num"</span><span class="p">].(</span><span class="kt">float64</span><span class="p">)</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="nx">num</span><span class="p">)</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>Nested data တွေကို access လုပ်ဖို့ ပြောင်းလဲမှုတွေ အများကြီး လုပ်ဖို့လိုပါတယ်။</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nx">strs</span> <span class="o">:=</span> <span class="nx">dat</span><span class="p">[</span><span class="s">"strs"</span><span class="p">].([]</span><span class="kd">interface</span><span class="p">{})</span>
<span class="nx">str1</span> <span class="o">:=</span> <span class="nx">strs</span><span class="p">[</span><span class="mi">0</span><span class="p">].(</span><span class="kt">string</span><span class="p">)</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="nx">str1</span><span class="p">)</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>JSON ကို custom data type တွေအဖြစ်လည်း decode လုပ်နိုင်ပါတယ်။
ဒီနည်းက ကျွန်တော်တို့ ပရိုဂရမ်တွေမှာ type-safety ထပ်ဖြည့်ပေးပြီး
decode လုပ်ထားတဲ့ data ကို access လုပ်တဲ့အခါ type assertion တွေ လုပ်စရာမလိုတဲ့ အားသာချက် ရှိပါတယ်။</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nx">str</span> <span class="o">:=</span> <span class="s">`{"page": 1, "fruits": ["apple", "peach"]}`</span>
<span class="nx">res</span> <span class="o">:=</span> <span class="nx">response2</span><span class="p">{}</span>
<span class="nx">json</span><span class="p">.</span><span class="nf">Unmarshal</span><span class="p">([]</span><span class="nb">byte</span><span class="p">(</span><span class="nx">str</span><span class="p">),</span> <span class="o">&</span><span class="nx">res</span><span class="p">)</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="nx">res</span><span class="p">)</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="nx">res</span><span class="p">.</span><span class="nx">Fruits</span><span class="p">[</span><span class="mi">0</span><span class="p">])</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>အပေါ်က ဥပမာတွေမှာ ကျွန်တော်တို့က data နဲ့ standard out ပေါ်က JSON ကိုယ်စားပြုမှုကြားမှာ
byte တွေနဲ့ string တွေကို အမြဲသုံးခဲ့ပါတယ်။ ကျွန်တော်တို့က JSON encoding တွေကို
<code>os.Stdout</code> သို့မဟုတ် HTTP response body တွေလိုမျိုး <code>os.Writer</code> တွေဆီ တိုက်ရိုက် stream လုပ်နိုင်ပါတယ်။</p>
</td>
<td class="code">
<pre class="chroma">
<span class="nx">enc</span> <span class="o">:=</span> <span class="nx">json</span><span class="p">.</span><span class="nf">NewEncoder</span><span class="p">(</span><span class="nx">os</span><span class="p">.</span><span class="nx">Stdout</span><span class="p">)</span>
<span class="nx">d</span> <span class="o">:=</span> <span class="kd">map</span><span class="p">[</span><span class="kt">string</span><span class="p">]</span><span class="kt">int</span><span class="p">{</span><span class="s">"apple"</span><span class="p">:</span> <span class="mi">5</span><span class="p">,</span> <span class="s">"lettuce"</span><span class="p">:</span> <span class="mi">7</span><span class="p">}</span>
<span class="nx">enc</span><span class="p">.</span><span class="nf">Encode</span><span class="p">(</span><span class="nx">d</span><span class="p">)</span>
<span class="p">}</span>
</pre>
</td>
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<table>
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<td class="docs">
</td>
<td class="code leading">
<pre class="chroma"><span class="gp">$</span> go run json.go
<span class="go">true
</span><span class="go">1
</span><span class="go">2.34
</span><span class="go">"gopher"
</span><span class="go">["apple","peach","pear"]
</span><span class="go">{"apple":5,"lettuce":7}
</span><span class="go">{"Page":1,"Fruits":["apple","peach","pear"]}
</span><span class="go">{"page":1,"fruits":["apple","peach","pear"]}
</span><span class="go">map[num:6.13 strs:[a b]]
</span><span class="go">6.13
</span><span class="go">a
</span><span class="go">{1 [apple peach]}
</span><span class="go">apple
</span><span class="go">{"apple":5,"lettuce":7}</span></pre>
</td>
</tr>
<tr>
<td class="docs">
<p>ဒီမှာ ကျွန်တော်တို့က Go မှာ JSON
အခြေခံကို ဖော်ပြခဲ့ပါတယ်၊
ဒါပေမယ့် ဒီထက်သိဖို့အတွက်
<a href="https://go.dev/blog/json">JSON and Go</a> blog post နဲ့
<a href="https://pkg.go.dev/encoding/json">JSON package docs</a>
ကို ကြည့်ပါလို့တိုက်တွန်းလိုပါတယ်။</p>
</td>
<td class="code empty">
</td>
</tr>
</table>
<p class="next">
နောက်ဥပမာ: <a href="xml">XML</a>.
</p>
<p class="footer">
by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> နှင့် <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
</p>
</div>
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