Vert.x: Blocking handler issue - vert.x

Question

I want to use blocking handler, but still get an error:
java.lang.IllegalStateException: Response has already been written
Here is my code:
Server.java
r.route("/api/details/send/").handler(BodyHandler.create());
r.route("/api/details/send/").handler(ctx-> {
JsonArray ja = ctx.getBodyAsJsonArray();
JsonArray params = new JsonArray();
vertx.executeBlocking(futur -> {
for(int i =0; i<ja.size();i++) {
JsonObject req = new JsonObject();
req.put("QUERY", "INSERT INTO detailsfacture VALUES ('',?,?,?,?,?,?,?)");
req.put("DB", "MYSQL_");
params.add(ja.getJsonObject(i).getValue("typefacture"))
.add(ja.getJsonObject(i).getValue("activites"))
.add(Integer.parseInt(ja.getJsonObject(i).getValue("qte").toString()))
.add(Double.parseDouble(ja.getJsonObject(i).getValue("pu").toString())
.add(ja.getJsonObject(i).getValue("unite"))
.add(Double.parseDouble(ja.getJsonObject(i).getValue("montant").toString())
.add(ja.getJsonObject(i).getValue("codefacture"));
req.put("PARAMS", params);
eb.send("EXECUTE", req, res -> {
if (res.succeeded()) {
params.clear();
ctx.response().putHeader("content-type", "application/json").end(res.result().body().toString());
} else {
ctx.response().putHeader("content-type", "application/json").end(res.cause().getMessage());
}
});
}
String result = "orsys";
futur.complete(result);
},resultat->{
ctx.response().putHeader(HttpHeaders.CONTENT_TYPE, "text/plain");
//resultat.result().toString();
});
});
MySql.java
eb.consumer("MYSQL_EXECUTE_WITH_PARAMS", req->{
try{
JsonObject reqParams = (JsonObject)req.body();
String sql = reqParams.getString("QUERY");
client.getConnection( connection -> {
if (connection.succeeded()) {
try{
SQLConnection con = connection.result();
con.updateWithParams(sql,reqParams.getJsonArray("PARAMS"), query -> {
if(query.succeeded()){
UpdateResult urs = query.result();
req.reply(urs.toJson());
//req.reply(query.result());
}else{
req.fail(24, "Err Request : "+query.cause().getMessage());
}
});
}catch(Exception e){
req.fail(24, "Err Conn Failed : "+e.getMessage());
}
} else {
req.fail(24, "Err No Connection : "+connection.cause().getMessage());
}
});
}catch(Exception e){
req.fail(24, e.getMessage());
}
});
P.S. : When I remove executeBlocking only the first records is registred in my database.
Regards.

Answer 1

You insert entities into detailsfacture in a loop. For each insert you call following:
ctx.response().putHeader("content-type", "application/json").end(res.result().body().toString());
As you can see you call the end(...) method of the response object. Thats where the IllegalStateException comes from. As the documentation states:
Once the response has ended, it cannot be used any more.
So you problem has nothing to do with the executeBlocking.
You should take a look at the write(...) method of HttpServerResponse. For each insert you should call write(...) instead of end(...). But this will only work if you know the complete length of the whole response because you need to set the header Content-length. If you are finished with all inserts you need to call end() to complete the response. Also you should only set the header once and not for each insert.
Now some additional comments. I don't see the need for executeBlocking in your case. Because of the problem with Content-length I recommend to wrap each insert with a Future and compose all of them with CompositeFuture. The Future futur is used the wrong way. The send(...) method of Event bus is not blocking and asynchronous. So the futur.complete(result) is called right after you send all your inserts. Also it's strange that the consumer consumes MYSQL_EXECUTE_WITH_PARAMS and the send sends to EXECUTE.

Answer 2

I tried another solution to get my query like that (?,?,...,?),(?,?,...,?),..,(?,?,...,?).
Here is my code :
public static String getMultipleInsertReq(String table, JsonArray columns,JsonArray data){
JsonObject tab= Tables.Tables_list.getJsonObject(table); // name of table
String sql = "";
if(tab != null){
sql = "INSERT INTO "+table + "( ";
if(columns == null){
columns = tab.getJsonArray("COLS"); //columns from ur database
}
if(columns!=null){
for(int i=0;i<columns.size();i++){
if(i==columns.size()-1){
sql+=columns.getString(i)+") VALUES";
}
else{
sql+=columns.getString(i)+",";
}
}
for(int i =0; i<data.size();i++){
for(int j=0; j<columns.size();j++){
if(j==columns.size()-1 && i!=data.size()-1){
sql+="?),";
}
else if (i==data.size()-1 && j==columns.size()-1){
sql+="?)";
}
else if (j==0){
sql+="(?,";
}
else{
sql+="?,";
}
}
}
return sql;
}
}
return null;
}
Hope it helps.
P.S.: it's only a query builder so you can adapt it depending on your needs.
Regards.