BREAKING: no longer deeply coerce argument to merge() #1339
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The methods `merge()` and `mergeDeep()` were the last places internally to call `fromJS()`, a method that is expensive, and limits the ability to use plain object and array values within immutable collections. This PR removes fromJS, not doing any deep coercion at all for `merge()` and simply passing object (incl array) values into the `merge()` function recursively for `mergeDeep()` operations, so only coercing those values that expect to be - leaving others alone. This is breaking because calls to `merge()` previously were implicitly `fromJS()`'d to get deeply immutable collections, however that is no longer the case. To update code which relied on this behavior, convert `collection.merge(x)` to `collection.merge(fromJS(x))`. Fixes #1293
…le-js/immutable-js/releases/tag/v4.0.0-rc.5) : No longer deeply coerce argument to merge() ([#1339](immutable-js/immutable-js#1339])) Previously, the argument provided to merge() was deeply converted to Immutable collections via fromJS(). This was the only function in the library which calls fromJS() indirectly directly, and it was surprising and made it difficult to understand what the result of merge() would be. Now, the value provided to merge() is only shallowly converted to an Immutable collection, similar to related methods in the library. This may change the behavior of your calls to merge().
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Hi, I've been using Immutable for years and I have about 500 merge calls in my project that I used to prevent transformin plain objects in immutable before an update or set. Is there any way I could pre process those merge and mergeDeep, mergeDeepIn, mergeIn, mergeDeepWith converting the argument in immutable without doing by hand? Thanks |
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Yes you can call fromJS() on any deep object tree, this is what merge was doing implicitly in v3, but v4 allows the use of plain JS structures with functional immutable methods |
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Ok, but is there any script to make this change automatically or I should change every one of the 500 merge usages in my code? |
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I’m not aware of a script, but if you’d like to contribute one, that would be a great positive impact for the community! Jscodeshift could be a good place to start |
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That sounds great! I will take a look at Jscodeshift in order to contribute. Thanks! |
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Hi @leebyron, I just created with one: https://github.com/renanbandeira/jscodeshift-upgrade-immutable Thanks for the tip. |
future-proof for immutable v4.x, which no longer calls fromJS on the argument passed to merge() and mergeDeep(): immutable-js/immutable-js#1339
future-proof for immutable v4.x, which no longer calls fromJS on the argument passed to merge() and mergeDeep(): immutable-js/immutable-js#1339
The methods
merge()andmergeDeep()were the last places internally to callfromJS(), a method that is expensive, and limits the ability to use plain object and array values within immutable collections.This PR removes fromJS, not doing any deep coercion at all for
merge()and simply passing object (incl array) values into themerge()function recursively formergeDeep()operations, so only coercing those values that expect to be - leaving others alone.This is breaking because calls to
merge()previously were implicitlyfromJS()'d to get deeply immutable collections, however that is no longer the case.To update code which relied on this behavior, convert
collection.merge(x)tocollection.merge(fromJS(x)).Fixes #1293