PreparedStatementCallback dynamic query parameters

Question

I have a PreparedStatementCallback in my DAO, my business requirement is to implement a JSON_SET function call (my backend is MySQL 8), so far I have done this:

SQL_Query = UPDATE MY_TABLE SET BLA_BLA=?, MY_JSON=JSON_SET('MY_JSON', ?), TIME =? WHERE KEY_1=? AND KEY_2=?

My snippet for executing this in batch:

    jdbcTemplate.execute(SQL_Query , new PreparedStatementCallback<Object>() {
                    int counter = 0, recordsUpdated = 0;
                    @Override
                    public Object doInPreparedStatement(PreparedStatement ps) throws DataAccessException {
                        try {
                            for (Entity entity : entities) {
                                if (++counter >= batchSize) {
                                    recordsUpdated += Arrays.stream(ps.executeBatch()).sum();
                                    ps.clearBatch();
                                    counter = 0;
                                }
                                try {
                                    switch (type) {
                                        case UPDATE:
                                        case PARTIAL_UPDATE:
                                            if(entity.getJsonMap() != null) {
                                                setPreparedStatementValuesForUpdate(ps, entity, type);
                                            }
                                            break;
                                        default:
                                            setPreparedStatementValues(ps, entity);
                                    }
                                    ps.addBatch();
                                } catch (JsonProcessingException e) {
                                    LOGGER.error("Error in converting JSON : {}", e.getLocalizedMessage());
                                }
                            }
                            recordsUpdated += Arrays.stream(ps.executeBatch()).sum();
                            ps.clearBatch();
                        } catch (Exception e) {
                            LOGGER.error("Error occurred : {}", e.getLocalizedMessage());
                            LOGGER.info("PS Query : {}", ps.toString());
                            e.printStackTrace();
                        }
                        return recordsUpdated;
                    }
                });
                return Integer.parseInt(insertCount == null ? "0" : insertCount.toString());


private void setPreparedStatementValuesForUpdate(PreparedStatement ps, Entity entity, TransactionType type)
                throws SQLException, JsonProcessingException {
            ps.setString(1, entity.getTime());
            if(TransactionType.PARTIAL_UPDATE.equals(type)) {
                final String dataToUpdate = StringEscapeUtils.escapeJson(getPartialJSONData(entity));
                if(StringUtils.isEmpty(dataToUpdate)) {
                    ps.setString(2, "'$.\"1\"', `JSON`->>'$.\"1\"'");
                } else {
                    ps.setString(2, dataToUpdate);
                }
            } else {
                ps.setString(2, objectMapper.writeValueAsString(entity.getDbdMeasures()));
            }
            ps.setString(3, entity.getTime());
            ps.setString(4, entity.getKey1());
            ps.setInt(5, entity.getKey2());
        }
private String getPartialJSONData(final Entity entity) {
        final StringBuilder builder = new StringBuilder();
        builder.append(String.join(",", entity.getJsonMap().entrySet().stream()
                .map(entry -> {
                    try {
                        return "'$.\"" + entry.getKey() + "\"', " + objectMapper.writeValueAsString(entry.getValue());
                    } catch (JsonProcessingException e) {
                        e.printStackTrace();
                    }
                    return null;
                }).collect(Collectors.toList())));
        return builder.toString();
    }

But I receive error that incorrect number of parameters passed to JSON_SET. That is because I passed entire string as one for parameters. And preparedstatement is good for avoiding sql injection. So I need to understand a possible workaround for this, or should I change the code itself altogether. I am considering JPA and jOOQ, provided I must get partial update for JSON document.

Answer 1

You cannot do it this way. Your second parameter is a single string, which means you are doing the equivalent of

JSON_SET('MY_JSON', '''$."1"'', `JSON`->>''$."1"'''

which obviously isn't correct

As you need to pass three (or 5, or 7, ...) values to JSON_SET , you'll need to use two parameters:

JSON_SET('MY_JSON', ?, ?)

And set those parameters appropriately. If you need to apply different operations depending on some logic, then you should use different UPDATE statements.