I have to add or conditions using the parameter values to the query.
Example: select * from users where email = "abc@xyz.com" or phone="1234123412";
The user might send both fields or only one. I want to do this in a loop for each field and add each one of them in or where condition.
val query = Users.selectAll()
**var predicates = Op.build { Users.id inList listOf<Int>()}**
for((k, v) in params) {
val value = URLDecoder.decode(v.first(), "UTF-8")
predicates = when(k) {
"email" -> predicates.or(Users.email eq value)
"phone" -> predicates.or(Users.phone eq value)
}
}
query.andWhere { predicates }
The above DSL produces the below SQL.
SELECT * from users where (((false = true) OR (users.email = "abc@xyz.com")) OR (users.phone = "1234567890"))
See that false = true? That is because, to use .or method, I have to initialize with a condition. The below given snippet is an unncessary line of code added to initialize the predicate.
var predicates = Op.build { Users.id inList listOf<Int>()}
What is the right way to initialize it so that I can seamlessly add multiple or and and predicates to the query?
First of all, I would advice to optimize your code like:
val params = mapOf<String, List<String>>()
val emails = params.filterKeys { it == "email" }.map { URLDecoder.decode(it.value.first(), "UTF-8") }
val phones = params.filterKeys { it == "phone" }.map { URLDecoder.decode(it.value.first(), "UTF-8") }
if (emails.isEmpty() && phones.isEmpty()) {
error("No suitable params were provided")
} else {
Users.select {
Users.email inList emails or (Users.phone inList phones)
}
}
UPD: orWhere function is available in Exposed since 0.16.1 version.
If you want to use pattern-matching (when) please define your local orWhere function the same way andWhere works:
fun Query.orWhere(andPart: SqlExpressionBuilder.() -> Op<Boolean>) = adjustWhere {
val expr = Op.build { andPart() }
if(this == null) expr
else this or expr
}
And use it like:
val query = Users.selectAll()
for((k, v) in params) {
val value = URLDecoder.decode(v.first(), "UTF-8")
predicates = when(k) {
"email" -> query.orWhere { Users.email eq value }
"phone" -> query.orWhere{ Users.phone eq value }
}
}
A trick would be to initialize predicates to null and define your own or and and on Op<Boolean>?:
// not sure x's type is correct here, the wiki doesn't give exact signatures
// may also need @JvmName to allow overloading
fun Op<Boolean>?.or(x: Op<Boolean>) = if (this != null) this.or(x) else x
...
var predicates: Op<Boolean>? = null
...
predicates = when(k) {
"email" -> predicates.or(Users.email eq value)
"phone" -> predicates.or(Users.phone eq value)
}
Whether it's worth the complication, I doubt: as Giacomo's comment mentions, the database will certainly optimize your original false = true out.