Goven (go-oven) is a go library that allows you to have a drop-in query language for your database schema.

• Take any gorm database object and with a few lines of code you can make it searchable.
• Safe query language not exposing SQL to your users.
• Easily extensible to support more advanced queries for your own schema.
• Basic grammar that allows for powerful queries.

Like a real life oven, it takes something raw (your database struct + a query input) and produces something specific (the schema specific parser + SQL output). We call the adaptors "recipes" that Goven can make. Currently Goven only supports a SQL adaptor, but the AST produced by the lexer/parser can easily be extended to other query languages.

You can make a basic query using gorm against your database, something like this:

reflection := reflect.ValueOf(&User{})
queryAdaptor, err := sql_adaptor.NewDefaultAdaptorFromStruct(reflection)
if err != nil {
    return nil, err
}

dbQuery := db.WithContext(ctx)
parsedQuery, err := queryAdaptor.Parse("(name=james AND age > 11) OR [email protected]")
if err != nil {
	return nil, err
}
dbQuery = query.Model(User{}).Where(parsedQuery.Raw, sql_adaptor.StringSliceToInterfaceSlice(parsedQuery.Values)...)
err = dbQuery.Find(&users).Error

The values are interpolated to prevent injection attacks.

You can also extend the basic query language with regex matchers. An example would be having a Tag struct on your User schema.

type User struct {
	gorm.Model
	name string
	tags []Tag
}

type Tag struct {
	gorm.Model
	Key string
	Value string
}

You can make this searchable my defining a regex and a custom matcher.

e.g if we want tags[key]=value to work then we can add the following matcher when creating the adaptor.

KeyValueRegex = `(tags)\[(.+)\]`

// keyValueMatcher is a custom matcher for and tags[y].
func keyValueMatcher(ex *goven_parser.Expression) (*goven_sql.SqlResponse, error) {
	reg, err := regexp.Compile(KeyValueRegex)
	if err != nil {
		return nil, err
	}
	slice := reg.FindStringSubmatch(ex.Field)
	if slice == nil {
		return nil, errors.New("didn't match regex expression")
	}
	if len(slice) < 3 {
		return nil, errors.New("regex match slice is too short")
	}
	sq := goven_sql.SqlResponse{
		Raw:    fmt.Sprintf("id IN (SELECT user_id FROM %s WHERE key=? AND value%s?)", slice[1], ex.Comparator),
		Values: []string{slice[2], ex.Value},
	}
	return &sq, nil
}

Sometimes we may not want particular fields to be searchable by end users. You can protect them by removing them from the fields mapping when creating your adaptor.

defaultFields := goven_sql.FieldParseValidatorFromStruct(gorm)
delete(defaultFields, "fieldname")

Goven has a simple syntax that allows for powerful queries.

Fields can be compared using the following operators:

=, !=, >=, <=, <, >, %

The % operator allows you to do partial string matching using LIKE.

Multiple queries can be combined using AND, OR.

Together this means you can build up a query like this:

model_name=iris AND version>=2.0

More advanced queries can be built up using bracketed expressions:

(model_name=iris AND version>=2.0) OR artifact_type=TENSORFLOW