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    What is CRUD

    In the software development world, CRUD consists of four operations - create, read, update, and delete.

    • Create: This operation would create a brand new entity. In terms of database, this would be INSERT statement.
    • Read: This operation would read something from the database and would not make any permanent changes to the database. In terms of database, this would be a READ operation.
    • Update: This operation would change an already existing entity. In terms of database it would be an UPDATE operation.
    • Delete: This operation would delete an entity. In terms of database this would be a DELETE operation.

    CRUD in action

    In Rails each resource typically performs these seven operations:

    VERBURI PatternController#ActionUsed forOperation
    GET/booksbooks#indexList booksREAD
    POST/booksbooks#createCreate a bookCREATE
    GET/books/newbooks#newForm for a new bookREAD
    GET/books/:idbooks#editForm for editing bookREAD
    GET/books/:idbooks#showShow info about bookREAD
    PATCH/books/:idbooks#updateUpdate info about bookUPDATE
    PUT/books/:idbooks#updateUpdate info about bookUPDATE
    DELETE/books/:idbooks#destroyDelete info about bookDELETE

    As we can see each of those seven actions could be assigned to one of these four operations - Create, Read, Update and Delete.

    REST and CRUD

    REST is an architectural system that deals with data through HTTP protocols. More info about REST is here.

    Typically software applications create RESTful APIs to handle CRUD operations. More info about CRUD operations is here.

    There aren't any changes to the application in this chapter. So let us clean up any accidental changes.

    1git clean -fd