Smaller, safer, easier to use and more flexible What is Trans? . While can be used only for fetching translations from maps or structs, it shines when coupled with for fetching and querying translations from the database. Trans is an Elixir library for managing translations embedded into data structures Trans Ecto The traditional approach to translation management consists on using database tables dedicated only to translation storage. For example we may have a table and a companion table. This is the approach used by the Ruby gem . posts post_translations Globalize While this approach is battle tested and works, it has a few disadvantages that can be improved: It complicates the database schema requiring a new table to be created for each translatable schema. It complicates the database migrations, since changes in the structure of a table must be replicated into the translation tables. It requires constant in order to filter or fetch records along with their translations. This has a visible impact on performance when multiple translatable schemas intervene in a query. JOINs Modern support unstructured datatypes such as JSON. , instead of having separated schemas for translations. This eliminates the need of maintaining duplicated database tables in sync and vastly reduces the number of JOIN clauses in queries. RDBMSs We can leverage this unstructured datatype support to embed the translations into a field of the schema itself While the database itself provides mechanisms for accessing unstructured data, itself does not provide a high level interface for accessing them easily. This is where Trans mission begins. Ecto Ecto allows you to write custom SQL fragments that can be used, among other things, to access JSON fields in the database. Writing those SQL fragments for each query that requires translations can get tiresome and error prone quickly. Trans generates the SQL fragments for you and validates them during compile time. Trans 1.0 sins Bypassing Ecto syntax for queries provides a nice syntax for query generation. Queries can be written using a series of macros (or functions, depending on which API you prefer) that allow for parameter interpolation, data binding, composition and prefixing. Ecto.Query Instead of enhancing Trans provided its own, different, API that didn’t interact with it. This caused a series of inconveniences and limitations. Ecto.Query.Api The first and most noticeable inconvenience appears when writting a query with some conditions on the translatable data. Instead of specifying the conditions when building the query, Trans 1.0 required to build the query first, and then pass it to a function that would add the required conditions. The first and most noticeable inconvenience appears when writing a query with some conditions on the translatable data. With a normal Ecto query you wold specify the conditions when building the query itself. Instead, Trans 1.0 required to build the query first, and then pass it to a function that would add the required conditions. Another problem of this approach is that . Joined schemas and associations were out… Ouch! conditions on translatable fields could be only added on the main schema of the query Mixing responsibilities in schema modules The translation container is the field that embeds the translations for the schema. Trans uses by default a field called translations, but allows this to be customized. In Trans 1.0, you had two options: calling the QueryBuilder functions directly or using Trans in your schema module to get some convenience functions set up to avoid repetition. Setting up the convenience functions was the most comfortable option, but it . added extra responsibilities and concerns to schema modules that did not belong there Unsafe against translation errors Trans 1.0 performed some basic checks against translation errors. For example, trying to add a query condition on an untranslatable field would result in a run-time . ArgumentError Trans 2.0 improves those checks and produces errors in the compilation phase instead on run-time. Trans 2.0 improvements Embracing Ecto Syntax for queries In Trans 2.0, the QueryBuilder component has been completely rewritten: . All the different functions in the QueryBuilder module have been unified into the macro. it now runs in compilation time and it’s only mission is the generation of the required SQL fragment translated/3 Being a macro allows the QueryBuilder to generate the SQL fragment in compile time and add it to the query being compiled. This way we can use the macro when creating Ecto queries and . translated/3 interact with the rest of functions and macros provided by **Ecto.Query** and **Ecto.Query.Api** Extracting responsabilities out of schema modules With Trans 2.0, that returns the Trans configuration for the module. modules only export an underscore function named **__trans__** This instead of spreading it among the client code. keeps client modules clean and keeps the logic contained into the QueryBuilder and Translator modules Safety checks as soon as possible As explained before, Trans 1.0 did some basic checks in runtime. Since the translation configuration for each module is set up during the compilation, Trans 2.0 uses it to perform safety checks before runtime. Want to translate a non existing field? Your application won’t compile. Want to translate a non-translatable field? Whooops… Your application won’t compile. Well… You get the idea. This makes Trans 2.0 safer and more approachable than the previous version. Future plans With this update Trans is in a good shape for being maintained and continuously improved. The main features that I want to include in future versions of Trans are: . MySQL 5.7 introduced a native JSON type that could be used by Trans in the same way as the PostgreSQL JSONB type. There is an in the repository to add support for this type. Support for MySQL open issue MySQL database driver . Currently Trans falls back to the default language when a translation does not exist. This behavior could be customized to check other locales before falling back to the default language. Specify available locales and custom fallback sequences . This is still an unfinished idea, but the main objective here would be to represent translations as embedded schemas. This way the translations could specify their own changesets and perform required validations or transformations. Make translations an embedded schema and create a custom Ecto type Wrapping up Trans first release was on June 4th, 2016, so it will reach a year of life soon. This has been an interesting journey where . Thank you all! we had 6 releases, 159 commits and have reached almost 250 downloads With this new release Trans has reached a level of maturity that makes it more usable, safe and maintainable for the time coming. So expect more improvements and features in the future. If you found a bug or have any ideas or comments feel free to post there or to . There are also interesting discussions in the . open an issue in GitHub Trans thread at Elixir Forum To finish this article I want to specially thank my friends , , , and for all the support ❤️. See you at the ! Óscar de Arriba Victor Ortiz Enol Iglesias Rubén Sierra dreamingechoes ElixirConf.EU
