From: matz@...
Date: 2015-12-13T15:51:28+00:00
Subject: [ruby-core:72099] [Ruby trunk - Bug #11762] Array#dig can raise TypeError: no implicit conversion of Symbol/String into Integer

Issue #11762 has been updated by Yukihiro Matsumoto.


Suppose you have a Hash/Array tree from JSON, with some attributes optional, you can expect three types of results;

(1) a value from valid tree structure
(2) nil from optional attributes
(3) exception from invalid tree

If #dig returns nil instead of exception, as you want, we cannot distinguish case 2 and case 3.

Matz.


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Bug #11762: Array#dig can raise TypeError: no implicit conversion of Symbol/String into Integer
https://bugs.ruby-lang.org/issues/11762#change-55515

* Author: Colin Kelley
* Status: Closed
* Priority: Normal
* Assignee: Yukihiro Matsumoto
* ruby -v: 2.3.0-preview2
* Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN, 2.2: UNKNOWN
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If you try to `dig` in an Array using a symbol or string, a `TypeError` exception will be raised:

irb> ['zero', 'one', 'two'].dig(:first)
TypeError: no implicit conversion of Symbol into Integer
    from (irb):1:in `dig'
    from (irb):1

I think it should return `nil` in this case.  The most typical use case for `dig` is to dig through parsed JSON and either find the result we expected or else `nil`.  Wouldn't it defeat the purpose of `dig` if we had to wrap calls to it in a `rescue` to handle the case that an Array was present where we expected a Hash?

Can we clarify the desired behavior for this case, then update the documentation and tests to reflect that?

---Files--------------------------------
11762.patch (3.19 KB)


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