Diesel CLI is an optional tool Diesel provides to manage your database schema. Its main two roles are to run database migrations, and to create a Rust file which represents your database schema.
The behavior of Diesel CLI can be configured through a toml file. By
default Diesel will look for diesel.toml in the same directory as
your Cargo.toml file. You can provide a different config file by
setting the DIESEL_CONFIG_FILE environment variable, or passing
--config-file on the command line. You can get a basic config file
with some defaults provided by running diesel setup.
As of Diesel 1.3, the file contains a single section,
[print_schema]. All fields in this file are optional.
The file field
This field specifies the file where you want the Rust representation
of your schema to live. When this field is present, commands which
modify database schema (such as diesel migration run) will
automatically run diesel print-schema, and output its results to
this file.
This means that you can modify your database schema without having to
worry about running a separate command to update your Rust code. It is
highly recommended that you use this field, to ensure that the Rust
representation of your database schema is always in sync with what is
actually in your database. Typically this is set to src/schema.rs.
Unlike other fields, this doesn't actually modify the behavior of
diesel print-schema. diesel print-schema will always output your
schema to stdout, regardless of whether this field is present or not.
The with_docs field
When this field is set to true, diesel print-schema will act as
though the --with-docs flag was passed by default. This places a doc
comment on all tables and columns.
The filter field
This field specifies which tables should be output by diesel
print-schema. It corresponds to the --only-tables and
--except-tables on the command line. Its value should be a map with
one of those two keys. For example:
[print_schema]
# This will cause only the users and posts tables to be output
filter = { only_tables = ["users", "posts"] }
# This will cause all tables *except* the comments table to be
# output
filter = { except_tables = ["comments"] }The schema field
Specifies which schema to use when searching for tables. When set,
diesel print-schema will always behave as though --schema were
passed. This field only affects PostgreSQL. If no value is provided,
the public schema will be searched.
The import_types field
This field adds use statements to the top of every table!
declaration. When set, diesel print-schema will behave as if
--import-types were passed. When no value is given, only types from
diesel::sql_types will be imported.
[print_schema]
# Add types from `diesel_full_text_search` like `tsvector`
import_types = ["diesel::sql_types::*", "diesel_full_text_search::types::*"]The patch_file field
Specifies a .patch file to be applied to your schema after it is
generated. Corresponds to the --patch-file option on the command
line. This option requires patch from diffutils to be installed on
your system.
We can't provide an option for every possible customization to this file that you might want to make. This serves as a general purpose catch-all for schema customizations.
The file should be a unified diff, which you can generate with diff
or git diff. It's highly recommended that you provide more than 3
context lines, especially if you have set import_types.
You can easily generate this file by making the changes you want to
schema.rs, and then running git diff -U6 > src/schema.patch.