Understanding Migrations in Ruby on Rails

UnderstandingMigrations in Ruby on Rails

> ActiveRecordMigration allow you to use Ruby to define changes to your database schema, making it possible to use a version control system to keep things synchronised with the actual code.

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Lists and arrays in Dart

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Converting Array to List in Scala

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Null-aware operators in Dart

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Three new language features just landed in the latest dev channel build of the Dart ! Collectively known as null-aware operators , these new features will help you reduce the code required to work with potentially null objects. I'm excited for these new abilities, because typing less is always a good thing. Read on to learn more, and be sure to try these new features on Dart Pad . ?? Use ?? when you want to evaluate and return an expression IFF another expression resolves to null. exp ?? otherExp is similar to ((x) => x == null ? otherExp : x)(exp) ??= Use ??= when you want to assign a value to an object IFF that object is null. Otherwise, return the object. obj ??= value is similar to ((x) => x == null ? obj = value : x)(obj) ?. Use ?. when you want to call a method/getter on an object IFF that object is not null (otherwise, return null). obj?.method() is similar to ((x) => x == null ? null : x.method())(obj) Yo
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