I'm looking at updating stored values in a RethinkDB using the C# RethinkDB.Driver library and I'm just not getting it right.
I can achieve an update by getting the result, altering that object then making a separate call to update with that object. When there are many calls to a record to update like this, the value being updated elsewhere whilst the application is working with the record.
TestingObject record = r.Db("test").Table("learning").Get("c8c54346-e35f-4025-8641-7117f12ebc5b").Run(_conn);
record.fieldNameIntValue = record.fieldNameIntValue + 1;
var result = r.Db("test").Table("learning").Get("c8c54346-e35f-4025-8641-7117f12ebc5b").Update(record).Run(_conn);
I've been trying something along these lines :
var result = r.Db("test").Table("learning").Get("c8c54346-e35f-4025-8641-7117f12ebc5b").Update(row => row["fieldNameIntValue"].Add(1)).Run(_conn);
but the result errors with Inserted value must be an OBJECT (got NUMBER):101 which suggests this is only passing the field value back instead of updating the object.
Ideally I'd like to update multiple columns at once, any advice is appreciated :)
This is an example that works in the ReQL data explorer. You can chain as may filters before the update as you want. I assume this will translate to the C# Driver, but I dont have any experience with that.
r.db('database').table('tablename').update({clicks: r.row("clicks").add(1)}).run().then(function(result){ ...
Thanks T Resudek your answer and a clearer head helped emphasised the need to map the calculation to the property.
Looking at the javadocs for update it has HashMap method which I followed with the c# library and it works.
var result = r.Db("test").Table("learning").Get("c8c54346-e35f-4025-8641-7117f12ebc5b").Update(row => r.HashMap("fieldNameIntValue",row["fieldNameIntValue"].Add(1))).Run(_conn);
I'd be interested to know if this is the right way or was a better way.
Related
NOTE: at this time I am stuck on 2sxc v9.43.2 on this project.
After selecting a set of records from my Content Type, I need to be able to duplicate them changing 1 of the fields along the way. Here is my almost-working idea so far. The use case is simple, they have Programs that people can register for. They change each Season, but only a little (prices, dates/times, etc). And they need the Current Season live and unchanged while they edit the Next Season. So we are still in the fall season (EntityId 1732) with 97 active programs. We want to click a button and clone all 97 programs as is, but IN TO the new Next Season (1735 below).
Two questions:
if this way works, what syntax would work on ent/Attributes to delivery the "object" as needed in the fields.Add() line
is there another 2sxc way to do this? Some other variant of the App.Data.Create() method or some other method in the API? I just need to duplicate the record with 1 field (Season) changed?
is there a better way to do this in the latest versions of 2sxc, v11.7+ ?
// we are going to duplicate the current Season's programs in to the new season
// cheating for now, pre-made new 1735 in Seasons, current is 1732
var programs = AsDynamic(App.Data["Programs"])
.Where(p => ((List<DynamicEntity>)p.Season).First().EntityId == selectedSeason.EntityId);
// #programs.Count() // 97
foreach(var copy in programs)
{
var fields = new Dictionary<string, object>();
var ent = AsEntity(copy);
foreach(var attr in ent.Attributes)
{
if(attr.Key == "Season")
{
fields.Add(attr.Key, new List<int> { 1735 });
}
else
{
fields.Add(attr.Key, ent.GetBestValue(attr.Key)); // object??
}
}
App.Data.Create("Programs", fields);
}
There are at least 3 ways to clone
Simple way using edit-ui
hard way using c# / server api
Semi-hard way using REST api
The simple way is to use the edit ui. You can see an example in the replace-dialog, there is a copy button there. This would open the edit UI with an existing item, but tell it it's a copy, so on save it would create a new one.
Combine this with a prefill or something and I think you would be good to go.
The second way is using the App.Data.Create - your code looks fairly good. I assume it also works and you were just wondering if there was a 1-liner - or am I mistaken?
The last way is using JS REST. Basically write some JS that gets an item, changes the object (resets the id) and posts it back to the endpoint for saving.
Just stumbled upon situation where I needed to create entity and set its field value, which has type of another entity. If that's your question #1, you need to add there EntityGuid.
fields.Add(attr.Key, attr.EntityGuid);. That should bind one entity to another one.
And no, I didn't stumble upon better way to copy entity then just to create a new one. At least so far.
I have a SQLite database for which I want to populate a new field based on an existing one. I want to derive the new field value using a C# function.
In pseudocode, it would be something like:
foreach ( record in the SQLite database)
{
my_new_field[record_num] = my_C#_function(existing_field_value[record_num]);
}
Having looked at other suggestions on StackOverflow, I'm using a SqliteDataReader to read each record, and then running a SQlite "UPDATE" command based on the specific RowId to update the new field value for the same record.
It works .... but it's REALLY slow and thrashes the hard drive like crazy. Is there really no better way to do this?
Some of the databases I need to update might be millions of records.
Thanks in advance for any help.
Edit:
In response to the comment, here's some real code in a legacy language called Concordance CPL. The important point to note is that you can read and write changes to the current record in one go:
int db;
cycle(db)
{
db->FIRSTFIELD = myfunction(db->SECONDFIELD);
}
myfunction(text input)
{
text output;
/// code in here to derive output from input
return output;
}
I have a feeling there's no equivalent way to do this in SQLite as SQL is inherently transactional, whereas Concordance allowed you to traverse and update the database sequentially.
The answer to this is to wrap all of the updates into a single transaction.
There is an example here that does it for bulk inserts:
https://www.jokecamp.com/blog/make-your-sqlite-bulk-inserts-very-fast-in-c/
In my case, it would be bulk updates based on RowID wrapped into a single transaction.
It's now working, and performance is many orders of magnitude better.
EDIT: per the helpful comment above, defining a custom C# function and then reference it in a single UPDATE command also works well, and in some ways is better than the above as you don't have to loop through within C# itself. See e.g. Create/Use User-defined functions in System.Data.SQLite?
This question has probably been asked correctly before, and I'll gladly accept an answer pointing me to the right spot. The problem is I don't know how to ask the question correctly to get anything returned in a search.
I'm trying to pull data from a 3rd party api (ADP) and store data in my database using asp.net core.
I am wanting to take the users returned from the API and store them in my database, where I have an ADP ancillary table seeded with the majority of the data from the api.
I would then like to update or add any missing or altered records in my database FROM the API.
I'm thinking that about using an ajax call to the api to retrieve the records, then either storing the data to another table and using sql to look for records that are changed between the two tables and making any necessary changes(this would be manually activated via a button), or some kind of scheduled background task to perform this through methods in my c# code instead of ajax.
The question I have is:
Is it a better fit to do this as a stored procedure in sql or rather have a method in my web app perform the data transformation.
I'm looking for any examples of iterating through the returned data and updating/creating records in my database.
I've only seen vague not quite what I'm looking for examples and nothing definitive on the best way to accomplish this. If I can find any reference material or examples, I'll gladly research but I don't even know where to start, or the correct terms to search for. I've looked into model binding, ajax calls, json serialization & deserialization. I'm probably overthinking this.
Any suggestions or tech I should look at would be appreciated. Thanks for you time in advance.
My app is written in asp.net core 2.2 using EF Core
* EDIT *
For anyone looking - https://learn.microsoft.com/en-us/dotnet/csharp/tutorials/console-webapiclient
This with John Wu's Answer helped me achieve what I was looking for.
If this were my project this is how I would break down the tasks, in this order.
First, start an empty console application.
Next, write a method that gets the list of users from the API. You didn't tell us anything at all about the API, so here is a dummy example that uses an HTTP client.
public async Task<List<User>> GetUsers()
{
var client = new HttpClient();
var response = await client.GetAsync("https://SomeApi.com/Users");
var users = await ParseResponse(response);
return users.ToList();
}
Test the above (e.g. write a little shoestring code to run it and dump the results, or something) to ensure that it works independently. You want to make sure it is solid before moving on.
Next, create a temporary table (or tables) that matches the schema of the data objects that are returned from the API. For now you will just want to store it exactly the way you retrieve it.
Next, write some code to insert records into the table(s). Again, test this independently, and review the data in the table to make sure it all worked correctly. It might look a little like this:
public async Task InsertUser(User user)
{
using (var conn = new SqlConnection(Configuration.ConnectionString))
{
var cmd = new SqlCommand();
//etc.
await cmd.ExecuteNonQueryAsync();
}
}
Once you know how to pull the data and store it, you can finish the code to extract the data from the API and insert it. It might look a little like this:
public async Task DoTheMigration()
{
var users = await GetUsers();
var tasks = users.Select
(
u => InsertUser(u)
);
await Task.WhenAll(tasks.ToArray());
}
As a final step, write a series of stored procedures or a DTS package to move the data from the temp tables to their final resting place. If you are using MS Access, you can write a series of queries and execute them in order with some VBA. At a high level it would:
Check for any records that exist in the temp table but not in the final table and insert them into the final table.
Check for any records that exist in the final table but not the temp table and remove them or mark them as deleted.
Check for any records in common that have different column values and update the final table.
Each of these development activities raises it own set of questions, of course, which you can post back to StackOverflow with details. As it is your question doesn't have enough specificity for a more in-depth answer.
So, I have this lambda expression and it works just fine
list = list.Where(x => x.ListaDocumentoCaixa.Any(d => d.Observacao.Contains(term.Trim())));
I must add that this column is a varchar(6000) field. So far, this has been working just fine as I mentioned, but just recently I've ran into an issue. It seems that if the term of the search occurs from position 4001 of the string and on, the query fails to return anything to me.
After some debbuging I've found this commented on the query produced by Entity Framework
-- p__linq__0: 'maria stela gonsa' (Type = String, Size = 4000)
Then after some research I found this to be Entity's common behaviour, however, I can't have this kind of limitation on the application. My question is: Is there any way to change this behaviour ? I would like very much to avoid having to write this query as plain text and run this with ExecuteQuery if possible.
Thanks in advance for the help!
I would recommend you follow the following article, assuming you are using SQL server, about how to create a full text search index, and use it in Entity Framework with C#.
Running LIKE statements (which is what Contains() maps to) is HIGHLY inefficient on large varchar fields.
https://www.mikesdotnetting.com/article/298/implementing-sql-server-full-text-search-in-an-asp-net-mvc-web-application-with-entity-framework
EDIT: The summary of the link is:
1.) Create a full text index on the field using SQL server's wizard. That full text field will allow CONTAINS and FREETEXT searches on the whole field, and be much more efficient.
2.) Write a stored procedure that joins the table in question to results from the free text index.
3.) Make an Entity Framework class to represent results from that stored procedure, and use EF to call in and return a list of those results.
I posted this question yesterday evening, which has led me to discover a huge problem!
I have a decimal column in my database called Units, anytime I set the value of the column to a NON ZERO, and SubmitChanges the column updates with the new value. If I try to set the value of the column to ZERO, the SubmitChanges does not update the column.
data.Units = this.ReadProperty<decimal>(UnitsProperty);
data.UnitPrice = this.ReadProperty<decimal>(UnitPriceProperty);
data.Price = this.ReadProperty<decimal>(PriceProperty);
I've taken a look at the DataContext log and I can see that the field with the ZERO value is not included in the query. Even if I try to hard code the change Linq ignores it.
data.Units = 0;
data.UnitPrice = 0;
data.Price = 0;
Needless to say this is killing me! Any ideas why this happening?
Solution
I figured out my problem with the help of the SO community. My problem was being caused by the fact when I created my entity to attach, the default value of the column was set to zero, so when it tried to assign the value to zero ... LinqToSql says hey ... nothing changed, so I am not updating the value.
What I am doing now ... just to make it work is the following:
ctx.DataContext.InvoiceItems.Attach(data, true);
That seems to force all the values to write themselves to the database. This works for now.
I have tried to reproduce this with a the following code, but for me it works.
using (DataClasses1DataContext ctx = new DataClasses1DataContext())
{
var obj = ctx.DecimalColumnTables.First();
Debug.Assert(obj.B != 0);
obj.B = 0;
ctx.SubmitChanges();
}
So I think there must be something special in your domain that causes this. I suggest you to create a such simple repro with your domain model and see what happens.
LINQ to SQL ignores updates to the current value, so if the field was already zero, you may not see any updates.
Off: The OR/M you use is LINQ to SQL. LINQ is the name of the querying capability in .NET, but LINQ does not define nor implement any update logic. So the issue relates to LINQ to SQL, not LINQ.
Obvious question, but are you sure the column is mapped in the dbml / mapping file?
Also - is it a calculated column? (i.e. price => units * unitprice)
I figured out my problem with the help of the SO community. My problem was being caused by the fact when I created my entity to attach, the default value of the column was set to zero, so when it tried to assign the value to zero ... LinqToSql says hey ... nothing changed, so I am not updating the value.
What I am doing now ... just to make it work is the following:
ctx.DataContext.InvoiceItems.Attach(data, true);
That seems to force all the values to write themselves to the database. This works for now.
Some more information ... I figured out my problem ... it's more of a lack of understanding about LinqToSql ... where I am doing:
private void Child_Update(Invoice parent)
{
using (var ctx = Csla.Data.ContextManager
.GetManager(Database.ApplicationConnection, false))
{
var data = new Gimli.Data.InvoiceItem()
{
InvoiceItemId = ReadProperty(InvoiceItemIdProperty)
};
ctx.DataContext.InvoiceItems.Attach(data);
if (this.IsSelfDirty)
{
// Update properties
}
}
}
I thought this would load the original values ... what happens is that it creates a new object with default values ... empty values, like 0 for decimals, Guid.Empty for uniqueidentifiers and so on.
So when it updates the properties it sees the Units already as 0 and it sets it to zero. Well LinqToSql doesn't recognize this as a change so it doesn't up date the field. So what I have had to do is the following:
ctx.DataContext.InvoiceItems.Attach(data, true);
Now all the modifications are generated in the update statement whether there is really a change or not. This works ... seems a bit hackish!
The correct answer is as many pointed out to use the special overload of Attach which accepts a boolean parameter to consider it as modified, (make the mistake of using another overload and it simply won't work):
ctx.DataContext.InvoiceItems.Attach(data, true);
Note however that you still might need to have a "Version" column in the table of type "timestamp".
I had this problem and all the suggestions I'd seen didn't apply or work.
But I found I had made a very simple mistake!
When updating the property I was actually calling a custom Set method (because there were other things that needed to be changed in response to the main property in question).
After hours of head scratching I noticed that my Set method was updating the private member not the public property, i.e. this._Walking = value;
All I had to do was change this to this.Walking = value; and it all started to work!