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Add example of extending SettableParameter

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Sean Corfield 2019-07-22 15:12:14 -07:00
parent 8c98f60a30
commit 5c21d17dec
1 changed files with 13 additions and 1 deletions
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doc/prepared-statements.md
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@ -27,7 +27,19 @@ If parameters are provided in the vector along with the SQL statement, in the ca
* `(set-parameter v ps i)` -- by default this calls `(.setObject ps i v)` (for `nil` and `Object`)
This can be extended to any Clojure data type, to provide a customized way to add specific types of values as parameters to any `PreparedStatement`. Note that you can extend this protocol via metadata so you can do it on a per-object basis if you need:
This can be extended to any Clojure data type, to provide a customized way to add specific types of values as parameters to any `PreparedStatement`. For example, to have all `java.time.LocalDate` and `java.time.LocalDateTime` objects converted to `java.sql.Timestamp` automatically:
```clojure
(extend-protocol p/SettableParameter
java.time.LocalDate
(set-parameter [^java.time.LocalDate v ^PreparedStatement s ^long i]
(.setTimestamp ps i (java.sql.Timestamp/valueOf (.atStartOfDay v))))
java.time.LocalDateTime
(set-parameter [^java.time.LocalDateTime v ^PreparedStatement s ^long i]
(.setTimestamp ps i (java.sql.Timestamp/valueOf v))))
```
Note that you can extend this protocol via metadata so you can do it on a per-object basis if you need:
```clojure
(with-meta obj {'next.jdbc.prepare/set-parameter (fn [v ps i]...)})