I'm trying to execute two queries against the database, the first one inserts the data then I do another query to get some data from a different collection then combine the result, but the zipWith is not being executed.
Mono<String> orderMono = orderDtoMono
.map(EntityDtoUtil::toEntity)
.flatMap(this.repository::insert)
.zipWhen(order -> this.clientRepository.findById(order. getOrderId()))
.map(i -> {
System.out.println("here");
return i.getT1().getOrderId() +" : "+i.getT2().getSuccessUrl();});
return orderMono;
The insert query works, however, the zipWhen is not executed and I get API result as 200 empty body.
The desired result would be the string created inside map operator at the end.
Zip will work only when both publishers return some data. Otherwise it will be empty.
In your case, you had just inserted a new record via repository .flatMap(this.repository::insert) - then you immediately expect this order id to be present via this.clientRepository.findById(order. getOrderId()). I believe it will be empty - so in your case you get empty response.
Do you have any DB trigger to insert records in other tables based on the new order id? Can you explain this - this.clientRepository.findById(order. getOrderId()) ?
Related
I'm trying to parse selected result from PostgreeSQL in Groovy, but something goes wrong, when I'm trying to parse it.
I used a lot of things, but I haven't reached the goal.
I've tried so:
I have three columns in postgre. One of the columns (document) is jsonb type and I want to parse it.
//instance of connection string to postrgre
PgAdmin pg = new
List<GroovyRowResult> result = pg.getSelectResult(Here goes select script)
for(Map oneRow in result) {
def document = oneRow.get("document")
println documnet //Well from here it works good, it prints jsonb data stored in document column.
def customerName = document.get("CustomerName") // it failes and goes on error, where CustomerName is inside jsonB.
}
I've also tried to use JsonSlurper, but it also fails.
I'm trying to return a simple, scalar string value from a Postgres DB using Knex. So far, everything I do returns a JSON object with a key (the column name) and the value, so I have to reach into the object to get the value. If I return multiple rows, then I get multiple JSON objects, each one repeating the key.
I could be returning multiple columns, in which case each row would at least need to be an array. I'm not looking for a special case where specifying a single column returns the value without the array -- I'm OK reaching into the array. I want to avoid the JSON object with the repetitive listing of column names as keys.
I've scoured the Knex docs but don't see how to control the output.
My table is a simple mapping table with two string columns:
CREATE TABLE public._suite
(
piv_id character(18) NOT NULL,
sf_id character(18) NOT NULL,
CONSTRAINT _suite_pkey PRIMARY KEY (piv_id)
)
When I build a query using Knex methods like
let myId = 'foo', table = '_suite';
return db(table).where('piv_id', myId).first(['sf_id'])
.then( function(id) { return(id); });
I get {"sf_id":"a4T8A0000009PsfUAE"} ; what I want is just "a4T8A0000009PsfUAE"
If I use a raw query, like
return db.raw(`select sf_id from ${table} where piv_id = '${myId}'`);
I get a much larger JSON object describing the result:
{"command":"SELECT","rowCount":1,"oid":null,"rows":[{"sf_id":"a4T8A0000009Q9HUAU"}],"fields":[{"name":"sf_id","tableID":33799,"columnID":2,"dataTypeID":1042,"dataTypeSize":-1,"dataTypeModifier":22,"format":"text"}],"_parsers":[null],"RowCtor":null,"rowAsArray":false}
What do I have to do to just get the value itself? (Again, I'm OK if it's in an array -- I just don't want the column names.)
Take a look at the pluck method.
db(table).where('piv_id', myId).pluck('sf_id'); // => will return you ["a4T8A0000009PsfUAE"]
That is meant to be read as a dual upsert operation, upsert the document then the array element.
So MongoDB is a denormalized store for me (we're event sourced) and one of the things I'm trying to deal with is the concurrent nature of that. The problem is this:
Events can come in out of order, so each update to the database need to be an upsert.
I need to be able to not only upsert the parent document but an element in an array property of that document.
For example:
If the document doesn't exist, create it. All events in this stream have the document's ID but only part of the information depending on the event.
If the document does exist, then update it. This is the easy part. The update command is just written as UpdateOneAsync and as an upsert.
If the event is actually to update a list, then that list element needs to be upserted. So if the document doesn't exist, it needs to be created and the list item will be upserted (resulting in an insert); if the document does exist, then we need to find the element and update it as an upsert, so if the element exists then it is updated otherwise it is inserted.
If at all possible, having it execute as a single atomic operation would be ideal, but if it can only be done in multiple steps, then so be it. I'm getting a number of mixed examples on the net due to the large change in the 2.x driver. Not sure what I'm looking for beyond the UpdateOneAsync. Currently using 2.4.x. Explained examples would be appreciated. TIA
Note:
Reiterating that this is a question regarding the MongoDB C# driver 2.4.x
Took some tinkering, but I got it.
var notificationData = new NotificationData
{
ReferenceId = e.ReferenceId,
NotificationId = e.NotificationId,
DeliveredDateUtc = e.SentDate.DateTime
};
var matchDocument = Builders<SurveyData>.Filter.Eq(s => s.SurveyId, e.EntityId);
// first upsert the document to make sure that you have a collection to write to
var surveyUpsert = new UpdateOneModel<SurveyData>(
matchDocument,
Builders<SurveyData>.Update
.SetOnInsert(f => f.SurveyId, e.EntityId)
.SetOnInsert(f => f.Notifications, new List<NotificationData>())){ IsUpsert = true};
// then push a new element if none of the existing elements match
var noMatchReferenceId = Builders<SurveyData>.Filter
.Not(Builders<SurveyData>.Filter.ElemMatch(s => s.Notifications, n => n.ReferenceId.Equals(e.ReferenceId)));
var insertNewNotification = new UpdateOneModel<SurveyData>(
matchDocument & noMatchReferenceId,
Builders<SurveyData>.Update
.Push(s => s.Notifications, notificationData));
// then update the element that does match the reference ID (if any)
var matchReferenceId = Builders<SurveyData>.Filter
.ElemMatch(s => s.Notifications, Builders<NotificationData>.Filter.Eq(n => n.ReferenceId, notificationData.ReferenceId));
var updateExistingNotification = new UpdateOneModel<SurveyData>(
matchDocument & matchReferenceId,
Builders<SurveyData>.Update
// apparently the mongo C# driver will convert any negative index into an index symbol ('$')
.Set(s => s.Notifications[-1].NotificationId, e.NotificationId)
.Set(s => s.Notifications[-1].DeliveredDateUtc, notificationData.DeliveredDateUtc));
// execute these as a batch and in order
var result = await _surveyRepository.DatabaseCollection
.BulkWriteAsync(
new []{ surveyUpsert, insertNewNotification, updateExistingNotification },
new BulkWriteOptions { IsOrdered = true })
.ConfigureAwait(false);
The post linked as being a dupe was absolutely helpful, but it was not the answer. There were a few things that needed to be discovered.
The 'second statement' in the linked example didn't work
correctly, at least when translated literally. To get it to work, I had to match on the
element and then invert the logic by wrapping it in the Not() filter.
In order to use 'this index' on the match, you have to use a
negative index on the array. As it turns out, the C# driver will
convert any negative index to the '$' character when the query is
rendered.
In order to ensure they are run in order, you must include bulk write
options with IsOrdered set to true.
Is there a way to use FirstOrDefault() inside a complex query but not throw an exception if it returns null value?
My query:
contex.Table1.Where(t => t.Property == "Value").FirstOrDefault()
.Object.Table2.Where(t => t.Property2 == "Value2").FirstOrDefault();
If the query on the first table (Table1) doesn't return an object the code throws an exception. Is there a way to make it return just null?
Try a SelectMany on Table2, without the intermediate FirstOrDefault():
context.Table1.Where(t1 => t1.Property1 == "Value1")
.SelectMany(t1 => t1.Table2.Where(t2 => t2.Property2 == "Value2"))
.FirstOrDefault();
Also, you might want to use SQL Profiler to check the SQL that is being sent by EF. I believe the query as constructed in your question will result in two queries being sent to the database; one for each FirstOrDefault().
You could build your own helper function, that takes IEnumerable
public static TSource CustomFirstOrDefault<TSource>(this IEnumerable<TSource> source)
{
return source.FirstOrDefault() ?? new List<TSource>();
}
This would effectively return an empty list, which, when called upon, providing your code in your Object property can handle nulls, won't bomb out, cause you'll just be returning a 0 item collection, instead of a null.
Only the first query with Where is a database query. As soon as you apply a "greedy" operator like FirstOrDefault the query gets executed. The second query is performed in memory. If Object.Table2 is a collection (which it apparently is) and you don't have lazy loading enabled your code will crash because the collection is null. If you have lazy loading enabled a second query is silently executed to load the collection - the complete collection and the filter is executed in memory.
You query should instead look like #adrift's code which would really be only one database query.
I have not clearly issue during query using two criterials like Id and Other. I use a Repository storing some data like id,iso,value. I have created an index("_id","Iso") to performs queries but queries are only returning my cursor if i use only one criterial like _id, but is returning nothing if a use two (_id, Iso) (commented code).
Are the index affecting the response or the query method are failing?
use :v1.6.5 and C# official.
Sample.
//Getting Data
public List<BsonObject> Get_object(string ID, string Iso)
{
using (var helper = BsonHelper.Create())
{
//helper.Db.Repository.EnsureIndex("_Id","Iso");
var query = Query.EQ("_Id", ID);
//if (!String.IsNullOrEmpty(Iso))
// query = Query.And(query, Query.EQ("Iso", Iso));
var cursor = helper.Db.Repository.FindAs<BsonObject>(query);
return cursor.ToList();
}
}
Data:
{
"_id": "2345019",
"Iso": "UK",
"Data": "Some data"
}
After that I have Updated my data using Update.Set() methods. I can see the changed data using MongoView. The new data are correct but the query is always returning the sames olds values. To see these values i use a page that can eventually cached, but if add a timestamp at end are not changing anything, page is always returning the same olds data. Your comments are welcome, thanks.
I do not recall offhand how the C# driver creates indexes, but the shell command for creating an index is like this:
db.things.ensureIndex({j:1});
Notice the '1' which is like saying 'true'.
In your code, you have:
helper.Db.Repository.EnsureIndex("_Id","Iso");
Perhaps it should be:
helper.Db.Repository.EnsureIndex("_Id", 1);
helper.Db.Repository.EnsureIndex("Iso", 1);
It could also be related to the fact that you are creating indexes on "_Id" and the actual id field is called "_id" ... MongoDB is case sensitive.
Have a quick look through the index documentation: http://www.mongodb.org/display/DOCS/Indexes