Generate (mysql)ddl from umlaut dsl files.

• Pass in a path to an umlaut file to umlaut.generators.ddl.mysql/gen.
• Returns a seq of maps containing :create and :drop keys where the values are the ddl to create and drop tables, respectively.

(require '[umlaut.generators.ddl.mysql :refer [gen]])
(gen "path/to/awesome/datamodel.umlaut")
=> ({:drop "DROP TABLE lisper" :create "CREATE TABLE lisper....."}
    ...)

A type level annotation with lang/ddl namespace will cause ddl to be emitted for that type. Nothing is emitted if this annotation is missing.

• @lang/ddl primary_key _ - Indicates the corresponding column is a primary key. If multiple fields have this annotation, a composite primary key will be emitted.
• @lang/ddl unique _ - Indicates the corresponding column has a unique constraint. If multiple fields have this annotation, a composite unique constraint will be emitted.
• @lang/ddl index _ - Indicates the corresponding column has an non-unique index.
• @lang/ddl type <THE TYPE> - Overrites the column's datatype with specified value.
• @lang/ddl type <THE TYPE>.<PARAMETER> - Overrites the column's datatype with specified value with a parameter. e.g. @lang/ddl type varchar.50
• @lang/ddl fk <OTHER TYPE>.<FIELD> - Adds a foreign key constraint
• @lang/ddl AUTO_INCREMENT true - Indicates that column should be auto incremented
• @lang/ddl suppress _ - Indicates that a column should not be emitted for this field. Useful when e.g. you want to expose a field that is not sourced as a column of a table.
• @doc "<the comment>" - renders a comment for the corresponding column

Umlaut enums map to enum columns.

A field type that is not optional e.g. String (instead of String?) adds a not null constraint to the corresponding column.

It is encouraged to be very specific about the datatype of the column using the @lang/ddl type annotation. Having that said, below is the default mapping.

 ;;umlaut     ;;ddl
{"ID"         "BIGINT"
 "String"     "TEXT"
 "Integer"    "INT"}

While this does not directly affect the rendered ddl, it adds information for sorting the tables topologically,

If a type Foo has field with a list a type, e.g.

@lang/ddl _ _
type Foo {
  someField: Bar[0..n]?`
}

Then the ddl generator infers that table foo should be created before table bar and performs a topological sort to determine the order of the emitted ddl.

This generator does not handle migrations, and is a simple mapping of a umlaut datamodel to ddl. Having that said, a tool to compare the schema equality between 2 database instances had been developed, which can be used to ensure that the 2 databases - one created from the generated ddl, and the other from the migrations - have exactly the same schema. Check it out!

Copyright Xcoo, Inc.

Licensed under the Apache License, Version 2.0.