GO-RQL-PARSER
Small, simple and lightweight library for Go web applications to translate RQL (Resource Query Language) queries to SQL
Usage
query := `and(eq(foo,3),lt(price,10))&sort(+price)`
p := rqlParser.NewParser() // Instanciate a new parser
// Parse the query and return the root node of the generated tree
rqlRootNode, err := p.Parse(query)
if err != nil {
panic("Query is not a valid rql : " + err.Error())
}
// Return the sql string for querying DB
sql, err := rqlParser.NewSqlTranslator(rqlNode).Sql()
if err != nil {
panic(err)
}
fmt.Println(sql)
// Print `WHERE ((foo=3) AND (price < 10)) ORDER BY price
Supported operators
The library support by default the following RQL operators :
- AND
- SQL Operator :
AND
- SQL Operator :
- OR
- SQL Operator :
OR
- SQL Operator :
- NE
- SQL Operator :
!=(When value isNULLit is translated to theIS NOTSQL operator)
- SQL Operator :
- EQ
- SQL Operator :
=(When value isNULLit is translated to theISSQL operator)
- SQL Operator :
- LIKE
- SQL Operator :
LIKE
- SQL Operator :
- MATCH
- SQL Operator :
ILIKE
- SQL Operator :
- GT
- SQL Operator :
>
- SQL Operator :
- LT
- SQL Operator :
<
- SQL Operator :
- GE
- SQL Operator :
>=
- SQL Operator :
- LE
- SQL Operator :
<=
- SQL Operator :
- SUM
- SQL Operator :
SUM
- SQL Operator :
- NOT
- SQL Operator :
NOT
- SQL Operator :
Append supported operators
It's easy to handle new operators by simply adding a TranslatorOpFunc to the SQLTranslator :
query := `or(eq(foo,42),between(price,10,100))`
rqlRootNode, err := p.Parse(query)
if err != nil {
panic("Query is not a valid rql : " + err.Error())
}
sqlTranslator := rqlParser.NewSqlTranslator(rqlNode)
// Before translating the node, just add the custom operator
// let's define a new function to handle beetween operator
betweenTranslatorFunc := func(n *rqlParser.RqlNode) (s string, err error) {
var (
min, max int64
field string
)
if len(n.Args) != 3 {
err = fmt.Errorf("between operator require 3 arguments")
return
}
for i, a := range n.Args {
if v, ok := a.(string); ok {
switch i {
case 0:
if rqlParser.IsValidField(v) {
field = v
} else {
return "", fmt.Errorf("First argument must be a valid field name (arg: %s)", v)
}
case 1, 2:
num, err := strconv.ParseInt(v, 10, 64)
if err != nil {
return "", fmt.Errorf("Argument n°%d must be an integer (arg: %s)", i, v)
}
if i == 1 {
min = num
} else {
max = num
}
}
} else {
err = fmt.Errorf("Between example function only support string arguments")
return
}
}
s = fmt.Sprintf("(%s >= %d) AND (%s <= %d)", field, min, field, max)
return
}
sqlTranslator.SetOpFunc(`between`, rqlParser.TranslatorOpFunc(betweenTranslatorFunc))
s, err := sqlTranslator.Sql()
if err != nil {
panic(err)
}
fmt.Println(s) // Will print : "WHERE ((foo=42) OR ((price >= 10) AND (price <= 100)))"
Contributions
Any contribution is welcome.
There is still many improvements that should be added to this library :
- Support type casting (ex:
string:42to force the SQLTranslator to handle 42 as a string) - Create a per database architecture translator as all databases doesn't support the same operators.