Arcade When 式が結果を返さない場合

DerekPhyn

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皆さん、こんにちは。私はArcadeは比較的新しいのですが、このWhen関数が理解できません。Right式を使うと、$feature.info_headline フィールドの最後の3文字を別のarcade式として適用した場合に正しく返されます。しかし、同じ式をWhen式の前に変数として適用すると、テスト時にエラーは出ませんが結果も返されません。どこが間違っているか教えていただけますか？変数に関して何かルールを見落としているのでしょうか？

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var right3 = Right($feature.info_headline, 3);
var warning_level = When(right3=='Red', 'Red', right3=='nge', 'Orange', 'Watch');

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この式で、新しいColor Styleを設定したいと思っています。つまり、$feature.info_headline フィールドの最後の3文字が 'Red' なら 'Red' を返し、最後の3文字が 'nge' なら 'Orange' を返し、それ以外は 'Watch' を返すようにしたいのです。

ネストされたIIf関数を使う方法もあるかもしれませんが、When関数で簡単にできると思っていました。

よろしくお願いします。

Derek

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XanderBakker

Hi Derek Phyn ,

That is correct you should always return the result of the expression. 

For readability especially when you have a lot of values to check you could spread the "when parts" over multiple lines like this:

<SPAN class="keyword token">var</SPAN> right3 <SPAN class="operator token">=</SPAN> <SPAN class="token function">Right</SPAN><SPAN class="punctuation token">(</SPAN>$feature<SPAN class="punctuation token">.</SPAN>info_headline<SPAN class="punctuation token">,</SPAN> <SPAN class="number token">3</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>
<SPAN class="keyword token">return</SPAN> <SPAN class="token function">When</SPAN><SPAN class="punctuation token">(</SPAN>right3<SPAN class="operator token">==</SPAN><SPAN class="string token">'Red'</SPAN><SPAN class="punctuation token">,</SPAN> <SPAN class="string token">'Warning - Red'</SPAN><SPAN class="punctuation token">,</SPAN> 
            right3<SPAN class="operator token">==</SPAN><SPAN class="string token">'nge'</SPAN><SPAN class="punctuation token">,</SPAN> <SPAN class="string token">'Warning - Orange'</SPAN><SPAN class="punctuation token">,</SPAN> 
            <SPAN class="string token">'Watch'</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN><SPAN class="line-numbers-rows"><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN></SPAN>

I also often use if - else if - else statements:

<SPAN class="keyword token">var</SPAN> right3 <SPAN class="operator token">=</SPAN> <SPAN class="token function">Right</SPAN><SPAN class="punctuation token">(</SPAN>$feature<SPAN class="punctuation token">.</SPAN>info_headline<SPAN class="punctuation token">,</SPAN> <SPAN class="number token">3</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>
<SPAN class="keyword token">if</SPAN> <SPAN class="punctuation token">(</SPAN>right3 <SPAN class="operator token">==</SPAN> <SPAN class="string token">'Red'</SPAN><SPAN class="punctuation token">)</SPAN> <SPAN class="punctuation token">{</SPAN>
    <SPAN class="keyword token">return</SPAN> <SPAN class="string token">'Warning - Red'</SPAN><SPAN class="punctuation token">;</SPAN>
<SPAN class="punctuation token">}</SPAN> <SPAN class="keyword token">else</SPAN> <SPAN class="keyword token">if</SPAN> <SPAN class="punctuation token">(</SPAN>right3 <SPAN class="operator token">==</SPAN> <SPAN class="string token">'nge'</SPAN><SPAN class="punctuation token">)</SPAN> <SPAN class="punctuation token">{</SPAN>
    <SPAN class="keyword token">return</SPAN> <SPAN class="string token">'Warning - Orange'</SPAN><SPAN class="punctuation token">;</SPAN>
<SPAN class="punctuation token">}</SPAN> <SPAN class="keyword token">else</SPAN> <SPAN class="punctuation token">{</SPAN>
    <SPAN class="keyword token">return</SPAN> <SPAN class="string token">'Watch'</SPAN><SPAN class="punctuation token">;</SPAN>
<SPAN class="punctuation token">}</SPAN><SPAN class="line-numbers-rows"><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN></SPAN>

You can also use a dictionary with the options:

<SPAN class="keyword token">var</SPAN> right3 <SPAN class="operator token">=</SPAN> <SPAN class="token function">Right</SPAN><SPAN class="punctuation token">(</SPAN>$feature<SPAN class="punctuation token">.</SPAN>info_headline<SPAN class="punctuation token">,</SPAN> <SPAN class="number token">3</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>
<SPAN class="keyword token">var</SPAN> dct <SPAN class="operator token">=</SPAN> <SPAN class="punctuation token">{</SPAN><SPAN class="string token">'Red'</SPAN><SPAN class="punctuation token">:</SPAN> <SPAN class="string token">'Warning - Red'</SPAN><SPAN class="punctuation token">,</SPAN>
           <SPAN class="string token">'nge'</SPAN><SPAN class="punctuation token">:</SPAN> <SPAN class="string token">'Warning - Orange'</SPAN><SPAN class="punctuation token">}</SPAN><SPAN class="punctuation token">;</SPAN>
<SPAN class="keyword token">if</SPAN> <SPAN class="punctuation token">(</SPAN><SPAN class="token function">HasKey</SPAN><SPAN class="punctuation token">(</SPAN>dct<SPAN class="punctuation token">,</SPAN> right3<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">)</SPAN> <SPAN class="punctuation token">{</SPAN>
    <SPAN class="keyword token">return</SPAN> dct<SPAN class="punctuation token">[</SPAN>right3<SPAN class="punctuation token">]</SPAN><SPAN class="punctuation token">;</SPAN>
<SPAN class="punctuation token">}</SPAN> <SPAN class="keyword token">else</SPAN> <SPAN class="punctuation token">{</SPAN>
    <SPAN class="keyword token">return</SPAN> <SPAN class="string token">'Watch'</SPAN><SPAN class="punctuation token">;</SPAN>
<SPAN class="punctuation token">}</SPAN><SPAN class="line-numbers-rows"><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN></SPAN>