Rails update attribute vs update attributes

Question

Object update attribute  only one field   Some Value   Object update attributes  field1   gt   value    field2   gt   value2    field3   gt   value3     Both of these will update an object without having to explicitly tell AR to update   Rails API says   for update attribute     Updates a single attribute and saves the record without going through the normal validation procedure  This is especially useful for boolean flags on existing records  The regular update attribute  method in Base  is replaced with this when the validations module is mixed in  which it is by default    for update attributes     Updates all  the attributes  from the passed-in Hash and saves the record  If the object is invalid  the saving will fail and false will be returned     So if I don t want to have the object validated I should use update attribute  What if I have this update on a before save  will it stackoverflow   My question is does update attribute also bypass the before save or just the validation   Also  what is the correct syntax to pass a hash to update attributes    check out my example at the top

User · Answer

Great answers  notice that as for ruby 1 9 and above you could  and i think should  use the new hash syntax for update attributes   Model update attributes column1   data   column2   data

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update attribute simply updates only one attribute of a model  but we can pass multiple attributes in update attributes method   Example   user   User last   update attribute user update attribute  status   active     It pass the validation   update attributes user update attributes first name   update name   status   active     it doesn t update if validation fails

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You might be interested in visiting this blog post concerning all the possible ways to assign an attribute or update record  updated to Rails 4  update attribute  update  update column  update columns etc  http   www davidverhasselt com set-attributes-in-activerecord   For example it differs in aspects such as running validations  touching object s updated at or triggering callbacks   As an answer to the OP s question update attribute does not by pass callbacks

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update attribute  This method update single attribute of object without invoking model based validation   obj   Model find by id params  id   obj update attribute  language     java      update attributes  This method update multiple attribute of single object and also pass model based validation   attributes     name   gt     BalaChandar      age   gt  23  obj   Model find by id params  id   obj update attributes attributes    Hope this answer will clear out when to use what method of active record

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To answer your question  update attribute skips pre save  validations  but it still runs any other callbacks like after save etc  So if you really want to  just update the column and skip any AR cruft  then you need to use  apparently   Model update all      see https   stackoverflow com a 7243777 32453

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Also worth noting is that with update attribute  the desired attribute to be updated doesn t need to be white listed with attr accessible to update it as opposed to the mass assignment method update attributes which will only update attr accessible specified attributes

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Recently I ran into update attribute vs  update attributes and validation issue  so similar names  so different behavior  so confusing   In order to pass hash to update attribute and bypass validation you can do   object   Object new object attributes       field1   value     field2   value2     field3   value3    object save  validate  false

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I think your question is if having an update attribute in a before save will lead to and endless loop  of update attribute calls in before save callbacks  originally triggered by an update attribute call   I m pretty sure it does bypass the before save callback since it doesn t actually save the record  You can also save a record without triggering validations by using  Model save false

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Please refer to update attribute  On clicking show source you will get following code           File vendor rails activerecord lib active record base rb  line 2614 2614        def update attribute name  value  2615          send name to s        value  2616          save false  2617        end   and now refer update attributes and look at its code you get          File vendor rails activerecord lib active record base rb  line 2621 2621        def update attributes attributes  2622          self attributes   attributes 2623          save 2624        end   the difference between two is update attribute uses save false  whereas update attributes uses save or you can say save true    Sorry for the long description but what I want to say is important  save perform validation   true   if perform validation is false it bypasses  skips will be the proper word  all the validations associated with save   For second question      Also  what is the correct syntax to pass a hash to update attributes    check out my example at the top    Your example is correct   Object update attributes  field1   gt   value    field2   gt   value2    field3   gt   value3     or  Object update attributes  field1   gt   value    field2   gt   value2    field3   gt   value3    or if you get all fields data  amp  name in a hash say params  user  here use just   Object update attributes params  user

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Tip  update attribute is being deprecated in Rails 4 via Commit a7f4b0a1  It removes update attribute in favor of update column

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update attribute and update attributes are similar  but with one big difference  update attribute does not run validations   Also    update attribute is used to update record with single attribute   Model update attribute  column name  column value1   update attributes is used to update record with multiple attributes   Model update attributes  column name1   gt  column value1   column name2   gt  column value2          These two methods are really easy to confuse given their similar names and works  Therefore  update attribute is being removed in favor of update column   Now  in Rails4 you can use Model update column  column name  column value  at the place of Model update attribute  column name  column value   Click here to get more info about update column

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