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    <p>Here's a little module to do it:</p> <pre><code>module NilToBlankAttrAccessor def nil_to_blank_attr_accessor(attr) attr_reader attr define_method "#{attr}=" do |value| value = '' if value.nil? instance_variable_set "@#{attr}", value end end end </code></pre> <p>Just mix it in:</p> <pre><code>class Foo extend NilToBlankAttrAccessor nil_to_blank_attr_accessor :bar end </code></pre> <p>And use it:</p> <pre><code>foo = Foo.new foo.bar = nil p foo.bar # =&gt; "" foo.bar = 'abc' p foo.bar # =&gt; "abc" </code></pre> <p><strong>How it works</strong></p> <p><code>NilToBlankAttrAccessor#nil_to_blank_attr_accessor</code> first defines the attr_reader normally:</p> <pre><code> attr_reader attr </code></pre> <p>Then it defines the writer by defining a method with the same name as the accessor, only with an "=" at the end. So, for attribute <code>:bar</code>, the method is named <code>bar=</code></p> <pre><code> define_method "#{attr}=" do |value| ... end </code></pre> <p>Now it needs to set the variable. First it turns nil into an empty string:</p> <pre><code> value = '' if value.nil? </code></pre> <p>Then use instance_variable_set, which does an instance variable assignment where the instance variable isn't known until runtime.</p> <pre><code> instance_variable_set "@#{attr}", value </code></pre> <p>Class Foo needs nil_to_blank_attr_accessor to be a class method, not an instance method, so it uses <code>extend</code> instead of <code>include</code>:</p> <pre><code>class Foo extend NilToBlankAttrAccessor ... end </code></pre>
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    1. USWayne Conrad
    1. USWayne Conrad
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    1. COThat will change not only `nil` but also `false` into `""`.
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      1. USsawa
    2. CO@sawa, Thank you. Fixed.
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      1. USWayne Conrad
    3. CO@WayneConrad That's a nice answer and great explanation :)
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      1. USArup Rakshit
 

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