cql

README

CQL: Compiled Query Language

What is cql?

Originally part of BaDaaS, CQL allows easy and safe persistence and querying of objects.

It's built on top of gorm, a library that actually provides the functionality of an ORM: mapping objects to tables in the SQL database. While gorm does this job well with its automatic migration then performing queries on these objects is somewhat limited, forcing us to write SQL queries directly when they are complex. CQL seeks to address these limitations with a query system that:

• Is compile-time safe: queries are validated at compile time to avoid errors such as comparing attributes that are of different types, trying to use attributes or navigate relationships that do not exist, using information from tables that are not included in the query, etc.; ensuring that a runtime error will not be raised.
• Is easy to use: the use of its query system does not require knowledge of databases, SQL languages or complex concepts. Writing queries only requires programming in Go and the result is easy to read.
• Is designed for real applications: the query system is designed to work well in real-world cases where queries are complex, require navigating multiple relationships, performing multiple comparisons, etc.
• Is designed so that developers can focus on the business model: its queries allow easy retrieval of model relationships to apply business logic to the model and it provides mechanisms to avoid errors in the business logic due to mistakes in loading information from the database.
• It is designed for high performance: the query system avoids as much as possible the use of reflection and aims that all the necessary model data can be retrieved in a single query to the database.

Language	Query
SQL	SELECT cities.* FROM cities INNER JOIN countries ON    countries.id = cities.country_id AND    countries.name = "France" WHERE cities.name = "Paris"
GORM	db.Where(  "cities.name = ?",  "Paris", ).Joins(  "Country",  db.Where(    "Country.name = ?",    "France",   ), ).Find(&cities)
CQL	cql.Query[models.City](   db,   conditions.City.Name.Is().Eq("Paris"),   conditions.City.Country(    conditions.Country.Name.Is().Eq("France"),   ), ).FindOne()

Is cql a copy of gorm-gen?

It is true that its aim seems to be the same:

100% Type-safe DAO API without interface{}

Although gorm-gen provides a more structured API than gorm for performing queries, providing methods like:

Where(conds ...gen.Condition) IUserDo

we can see from this signatures that, for example, the Where method receives parameters of type gen.Condition. In this way, conditions from different models could be mixed without generating a compilation error:

u := query.User
c := query.Company
user, err := u.Where(c.Name.Eq("franco")).First()

which would generate a runtime error during the execution of the generated SQL:

SELECT * FROM `users` WHERE `companies`.`name` = "franco"
no such column: companies.name

Because of this, cql decides to go further in type safety and check that the conditions are of the correct model, that the compared values are of the same type, that the models are included in the query and more, ensuring that a runtime error will not be raised.

Documentation

https://compiledquerylenguage.readthedocs.io/en/latest/

Contributing

See this section to view the cql contribution guidelines.

License

CQL is Licensed under the Mozilla Public License Version 2.0.

Documentation

Index

• Variables
• func And[T model.Model](firstCondition condition.WhereCondition[T], ...) condition.WhereCondition[T]
• func Delete[T model.Model](tx *gorm.DB, firstCondition condition.Condition[T], ...) *condition.Delete[T]
• func Not[T model.Model](firstCondition condition.WhereCondition[T], ...) condition.WhereCondition[T]
• func Open(dialector gorm.Dialector, opts ...gorm.Option) (*gorm.DB, error)
• func Or[T model.Model](firstCondition condition.WhereCondition[T], ...) condition.WhereCondition[T]
• func Query[T model.Model](tx *gorm.DB, conditions ...condition.Condition[T]) *condition.Query[T]
• func Transaction[RT any](db *gorm.DB, toExec func(*gorm.DB) (RT, error), opts ...*sql.TxOptions) (RT, error)
• func True[T model.Model]() condition.Condition[T]
• func Update[T model.Model](tx *gorm.DB, firstCondition condition.Condition[T], ...) *condition.Update[T]

Variables

var (
	ErrFieldModelNotConcerned   = condition.ErrFieldModelNotConcerned
	ErrAppearanceMustBeSelected = condition.ErrAppearanceMustBeSelected
	ErrAppearanceOutOfRange     = condition.ErrAppearanceOutOfRange
	ErrFieldIsRepeated          = condition.ErrFieldIsRepeated

	ErrMoreThanOneObjectFound = condition.ErrMoreThanOneObjectFound
	ErrObjectNotFound         = condition.ErrObjectNotFound

	ErrUnsupportedByDatabase = condition.ErrUnsupportedByDatabase
	ErrOrderByMustBeCalled   = condition.ErrOrderByMustBeCalled

	ErrOnlyPreloadsAllowed = condition.ErrOnlyPreloadsAllowed
	ErrRelationNotLoaded   = preload.ErrRelationNotLoaded
)

Functions

func And

func And[T model.Model](firstCondition condition.WhereCondition[T], conditions ...condition.WhereCondition[T]) condition.WhereCondition[T]

And allows the connection of multiple conditions by the AND logical connector.

Its use is optional as it is the default connector.

Example:

cql.And(conditions.City.Name.Is().Eq("Paris"), conditions.City.ZipCode.Is().Eq("75000"))

func Delete

func Delete[T model.Model](tx *gorm.DB, firstCondition condition.Condition[T], conditions ...condition.Condition[T]) *condition.Delete[T]

Create a Delete to which the conditions are applied inside transaction tx.

At least one condition is required to avoid deleting all values in a table. In case this is the desired behavior, use cql.True.

For details see https://compiledquerylenguage.readthedocs.io/en/latest/cql/delete.html

func Not

func Not[T model.Model](firstCondition condition.WhereCondition[T], conditions ...condition.WhereCondition[T]) condition.WhereCondition[T]

Not allows the negation of the conditions within it. Multiple conditions are connected by an AND by default.

Example:

cql.Not(conditions.City.Name.Is().Eq("Paris"), conditions.City.Name.Is().Eq("Buenos Aires"))

translates as

NOT (name = "Paris" AND name = "Buenos Aires")

func Open

func Open(dialector gorm.Dialector, opts ...gorm.Option) (*gorm.DB, error)

Open initialize db session based on dialector

For details see https://compiledquerylenguage.readthedocs.io/en/latest/cql/connecting_to_a_database.html

func Or

func Or[T model.Model](firstCondition condition.WhereCondition[T], conditions ...condition.WhereCondition[T]) condition.WhereCondition[T]

Or allows the connection of multiple conditions by the OR logical connector.

Example:

cql.Or(conditions.City.Name.Is().Eq("Paris"), conditions.City.Name.Is().Eq("Buenos Aires"))

func Query

func Query[T model.Model](tx *gorm.DB, conditions ...condition.Condition[T]) *condition.Query[T]

Create a Query to which the conditions are applied inside transaction tx

For details see https://compiledquerylenguage.readthedocs.io/en/latest/cql/query.html

func Transaction

func Transaction[RT any](
	db *gorm.DB,
	toExec func(*gorm.DB) (RT, error),
	opts ...*sql.TxOptions,
) (RT, error)

Executes the function "toExec" inside a transaction The transaction is automatically rolled back in case "toExec" returns an error opts can be used to pass arguments to the transaction

func True

func True[T model.Model]() condition.Condition[T]

True represents a condition that is always true.

In general, it should not be used. It can only be useful in case you want to perform an operation on all models in a table.

func Update

func Update[T model.Model](tx *gorm.DB, firstCondition condition.Condition[T], conditions ...condition.Condition[T]) *condition.Update[T]

Create a Update to which the conditions are applied inside transaction tx.

At least one condition is required to avoid updating all values in a table. In case this is the desired behavior, use cql.True.

For details see https://compiledquerylenguage.readthedocs.io/en/latest/cql/update.html