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PONSNull handling for NSManagedObject properties values
 

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  1. PONSNull handling for NSManagedObject properties values
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    <p>I'm setting values for properties of my <code>NSManagedObject</code>, these values are coming from a <code>NSDictionary</code> properly serialized from a JSON file. My problem is, that, when some value is <code>[NSNull null]</code>, I can't assign directly to the property:</p> <pre><code> fight.winnerID = [dict objectForKey:@"winner"]; </code></pre> <p>this throws a <code>NSInvalidArgumentException</code></p> <pre><code>"winnerID"; desired type = NSString; given type = NSNull; value = &lt;null&gt;; </code></pre> <p>I could easily check the value for <code>[NSNull null]</code> and assign <code>nil</code> instead:</p> <pre><code>fight.winnerID = [dict objectForKey:@"winner"] == [NSNull null] ? nil : [dict objectForKey:@"winner"]; </code></pre> <p>But I think this is not elegant and gets messy with lots of properties to set.</p> <p>Also, this gets harder when dealing with <code>NSNumber</code> properties:</p> <pre><code>fight.round = [NSNumber numberWithUnsignedInteger:[[dict valueForKey:@"round"] unsignedIntegerValue]] </code></pre> <p>The <code>NSInvalidArgumentException</code> is now:</p> <pre><code>[NSNull unsignedIntegerValue]: unrecognized selector sent to instance </code></pre> <p>In this case I have to treat <code>[dict valueForKey:@"round"]</code> before making an <code>NSUInteger</code> value of it. And the one line solution is gone.</p> <p>I tried making a @try @catch block, but as soon as the first value is caught, it jumps the whole @try block and the next properties are ignored.</p> <p>Is there a better way to handle <code>[NSNull null]</code> or perhaps make this entirely different but easier?</p>
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    1. USLucien
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      1. USMark W
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    1. COOut of curiosity, in the number case, why are you unwrapping and re-wrapping the number? What's wrong with `fight.round = [dict objectForKey:@"round"]`?
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      1. USKevin Ballard
    2. CO@KevinBallard Unacceptable type of value for attribute: property = "round"; desired type = NSNumber; given type = __NSCFString; value = 3.
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      1. USLucien
    3. COIf it's an `NSString`, then `-unsignedIntegerValue` won't work, because that method isn't defined on `NSString`. You could use `-integerValue` instead, which is defined on both `NSNumber` and `NSString`.
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