How can I Insert JSON object into Postgres using Java preparedStatement?

user_5302866 0
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I’m struggling to insert a JSON object into my postgres v9.4 DB. I have defined the column called "evtjson" as type json (not jsonb).

I am trying to use a prepared statement in Java (jdk1.8) to insert a Json object (built using JEE javax.json libraries) into the column, but I keep running into SQLException errors.

I create the JSON object using:

JsonObject mbrLogRec = Json.createObjectBuilder().build();
…
mbrLogRec = Json.createObjectBuilder()
                .add("New MbrID", newId)
                .build();

Then I pass this object as a parameter to another method to write it to the DB using a prepared statement. (along with several other fields) As:

pStmt.setObject(11, dtlRec);

Using this method, I receive the following error:

org.postgresql.util.PSQLException: No hstore extension installed. at org.postgresql.jdbc.PgPreparedStatement.setMap(PgPreparedStatement.java:553) at org.postgresql.jdbc.PgPreparedStatement.setObject(PgPreparedStatement.java:1036)

I have also tried:

pStmt.setString(11, dtlRec.toString());
pStmt.setObject(11, dtlRec.toString());

Which produce a different error:

Event JSON: {"New MbrID":29}

SQLException: ERROR: column "evtjson" is of type json but expression is of type character varying

Hint: You will need to rewrite or cast the expression.

But, at least this tells me that the DB is recognizing the column as type JSON. I did try installing the hstore extension, but it then told me that it was not an hstore object.

OracleDocs shows a number of various methods to set the parameter value in the preparedStatement, but I'd rather not try them all if someone knows the answer. (http://docs.oracle.com/javase/8/docs/api/java/sql/PreparedStatement.html) These also reference an additional parameter, SQLType, but I can't find any reference to these.

Should I try setAsciiStream? CharacterStream? CLOB?

prepared-statement postgresql json java
8 Answers

Most answers here defines ways of inserting into postgres json field with jdbc in a non-standard way, ie. it is db implementation specific. If you need to insert a java string into a postgres json field with pure jdbc and pure sql use:

preparedStatement.setObject(1, "{}", java.sql.Types.OTHER)

This will make the postgres jdbc driver (tested with org.postgresql:postgresql:42.2.19) convert the java string to the json type. It will also validate the string as being a valid json representation, something that various answers using implicit string casts does not do - resulting in the possibility of corrupt persisted json data.

user_3582440

As others have mentioned, your SQL string needs to explicitly cast the bind value to the PostgreSQL json or jsonb type:

insert into t (id, j) values (?, ?::json)

Now you can bind the string value. Alternatively, you can use a library that can do it, for example jOOQ (works out of the box) or Hibernate (using a third party UserType registration). The benefits of this is that you don't have to think about this every time you bind such a variable (or read it). A jOOQ example:

ctx.insertInto(T)
   .columns(T.ID, T.J)
   .values(1, JSON.valueOf("[1, 2, 3]"))
   .execute();

Behind the scenes, the same cast as above is always generated, whenever you work with this JSON (or JSONB) data type.

(Disclaimer: I work for the company behind jOOQ)

user_5217990

if using spring boot: adding the following line to application.properties helped:

spring.datasource.hikari.data-source-properties.stringtype=unspecified

as Wero wrote:

This tells PostgreSQL that all text or varchar parameters are actually of unknown type

user_64475290
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