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?
This behaviour is quite annoying since JSON strings are accepted without problems when used as literal strings in SQL commands.
There is a already an issue for this in the postgres driver Github repository (even if the problem seems the be the serverside processing).
Besides using a cast (see answer of
#a_horse_with_no_name) in the sql string, the issue author offers two additional solutions:
Use a parameter stringtype=unspecified in the JDBC connection URL/options.
This tells PostgreSQL that all text or varchar parameters are actually
of unknown type, letting it infer their types more freely.
Wrap the parameter in a org.postgresql.util.PGobject:
PGobject jsonObject = new PGobject();
jsonObject.setType("json");
jsonObject.setValue(yourJsonString);
pstmt.setObject(11, jsonObject);
You can do it like this and you just need the json string:
Change the query to:
String query = "INSERT INTO table (json_field) VALUES (to_json(?::json))"
And set the parameter as a String.
pStmt.setString(1, json);
You have two options:
Use statement.setString(jsonStr) and then handle the conversion in the sql statement:
PreparedStatement statement = con.prepareStatement(
"insert into table (jsonColumn) values (?::json)");
statement.setString(1, jsonStr);
Another option is to use PGobject to create a custom value wrapper.
PGobject jsonObject = new PGobject();
PreparedStatement statement = con.prepareStatement(
"insert into table (jsonColumn) values (?)");
jsonObject.setType("json");
jsonObject.setValue(jsonStr);
statement.setObject(1, jsonObject);
I personally prefer the latter as the query is cleaner
Passing the JSON as a String is the right approach, but as the error message tells you, you need to cast the parameter in the INSERT statement to a JSON value:
insert into the_table
(.., evtjson, ..)
values
(.., cast(? as json), ..)
Then you can use pStmt.setString(11, dtlRec.toString()) to pass the value
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.
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)
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
Instead of passing json object pass its string value and cast it to json in the query.
Example:
JSONObject someJsonObject=..........
String yourJsonString = someJsonObject.toString();
String query = "INSERT INTO table (json_field) VALUES (to_json(yourJsonString::json))";
this worked for me.
Related
I want to execute the JSON Query using the the following query
string sql = "SELECT JSON_OBJECT ('customerid' VALUE customerID, 'customerutility' VALUE customerutility) FROM customerTABLE";
I need to run this from Java application and store the results in a file.
statement = connection.createStatement();
ResultSet rs = statement.executeQuery(sql);
I am guessing the executeQuery returns a JSON OBJECT. I am not quite sure how to get this object to serialize to a file.
any help in this is greatly appreciated
Honestly I never worked with SQLServer, but I will take the liberty of answering because nobody has done so far..
If I were in your place I would try one of the following options:
I would try to read the JSON as if it were a string: rs.getString("json") where "json" is used as alias
If the first approach doesn't work, I would try with an explicit string cast on the sql side
Both the previous solutions derive from the assumption that, if the json will be written on a file, no typing is necessary, but a string representation of the json is enough.
Otherwise my approach would be to read in the classic way the fields of the table and then turn each row into a json java side, and this operation is very simple:
Json.createObjectBuilder()
.add("customerid", 1)
.add("customerUtility", "something")
.build();
I am using geotools library to extract the location information. With that I am getting an object of type
class com.vividsolutions.jts.geom.MultiPolygon
I now want to store this field in my mysql table with a jdbc connection .
When I directly try to insert it as
pstmtInsert.setObject(4, geoobject)
I am getting this error
Exception in thread "main" com.mysql.jdbc.MysqlDataTruncation: Data truncation: Cannot get geometry object from data you send to the GEOMETRY field
Answer
You need to convert the geometry object you have to well known text. You'll find information on how to do that in the vividsolutions API documentation.
geoobject.toText();
Insert / Update the data using the mysql GeomFromText method.
INSERT INTO geom VALUES (GeomFromText(#g));
It can be binary as well, e.g.
PreparedStatement preparedStatement = connection.prepareStatement
("INSERT INTO table (point, polygon) VALUES (PointFromWKB(?), GeomFromWKB(?))");
WKBWriter writer = new WKBWriter();
preparedStatement.setBytes(1, writer.write(point));
preparedStatement.setBytes(2, writer.write(polygon));
preparedStatement.executeUpdate();
MySql can't know how to store your GEO object, or what is his size. You should not store the object the way you're trying.
The PreparedStatement#setObject() documentation says :
The JDBC specification specifies a standard mapping from Java Object types to SQL types. The given argument will be converted to the corresponding SQL type before being sent to the database.
[...]
This method throws an exception if there is an ambiguity, for example, if the object is of a class implementing more than one of the interfaces named above.
I'm trying to pass an array of strings to a select statement and I keep getting the error:
org.postgresql.util.PSQLException: Can't infer the SQL type to use for an instance of clojure.lang.PersistentVector. Use setObject() with an explicit Types value to specify the type to use.
I know that the column type is correct, it looks as if passing a vector is the culprit. What is the correct way to do this?
The sql statement is formatted like so:
"SELECT * FROM said_table WHERE item_id IN (?)"
This answer assumes you are using jdbc and not korma or something like it and need to generate the sql directly instead of going through some tool:
the in directive requires you to crate one ? for each item in the list. I end up using this pattern when something else requires me to build the SQL manually:
(let [placeholders (s/join ", " (repeat (count things-go-here) "?"))
query "SELECT * FROM said_table WHERE item_id IN (%s)"]
(exec-raw [(format query placeholders) things-go-here] :results)
....)
I am using geotools library to extract the location information. With that I am getting an object of type
class com.vividsolutions.jts.geom.MultiPolygon
I now want to store this field in my mysql table with a jdbc connection .
When I directly try to insert it as
pstmtInsert.setObject(4, geoobject)
I am getting this error
Exception in thread "main" com.mysql.jdbc.MysqlDataTruncation: Data truncation: Cannot get geometry object from data you send to the GEOMETRY field
Answer
You need to convert the geometry object you have to well known text. You'll find information on how to do that in the vividsolutions API documentation.
geoobject.toText();
Insert / Update the data using the mysql GeomFromText method.
INSERT INTO geom VALUES (GeomFromText(#g));
It can be binary as well, e.g.
PreparedStatement preparedStatement = connection.prepareStatement
("INSERT INTO table (point, polygon) VALUES (PointFromWKB(?), GeomFromWKB(?))");
WKBWriter writer = new WKBWriter();
preparedStatement.setBytes(1, writer.write(point));
preparedStatement.setBytes(2, writer.write(polygon));
preparedStatement.executeUpdate();
MySql can't know how to store your GEO object, or what is his size. You should not store the object the way you're trying.
The PreparedStatement#setObject() documentation says :
The JDBC specification specifies a standard mapping from Java Object types to SQL types. The given argument will be converted to the corresponding SQL type before being sent to the database.
[...]
This method throws an exception if there is an ambiguity, for example, if the object is of a class implementing more than one of the interfaces named above.
I'm using JasperReports engine, and one of the reports gets data from database executing SQL statement. Is there a way to pass parameters to that query?
Thanks in advance!
First, create a new parameter in your report. Then insert the parameter in your query, for example:
SELECT name, department FROM employees WHERE employee_id = $P{employeeId}
Make sure your parameter types matches the data type of the columns in your database. Finally, simply pass your parameters to the JasperReports engine. An example would be:
parameters.put("employeeId", Long.valueOf(14309));
JasperRunManager.runReportToPdf(reportFile, parameters, connection);