How To Merge Precision And Recall


Hello everybody,

today I continue writing notes about measuring quality of learning. You can read my previuos artcile 1 and article 2 about measures of quality of learning. If to summarize two of those articles we have the following:

  1. accuracy is good measure, but if samplings is unbalanced then accuracy can have great numbers, but total model will be very bad.
  2. precision tells you how objects model a(x) can find
  3. precision and recall work fine on unbalanced samplings

And then question arises, is it possible somehow to merge them, but not as accuracy but as something more meaningful then accuracy?

I'll decribe different ways to describe it going from worsest to better and hopefully the best algorithm.


Let's consider first example: average value of precision and recall. Take a look at the following formula:

Take a look how possible chart can look like:

First of all you can see lines drawed with step 0.2 . That is because formula of precision is linear formula. 

consider following case. You've made a model that gives you following criteria

precision = 0.1

recall = 1

A = 0.5 * (1 + 0.1) = 0.55

In reality that can be constant output model, that always says 1 as response, and if you have biased selection set which is 99% with 1 and only 1% with -1. That model is useless, but on chart it will look like this:

Consider another model:

precision 0.55

recall 0.55

A = 0.55

Combined picture will look like this:

second model is much better then the first one, but both dots live on the same line giving idea that both of them are equally good. But in reality they are not. The second one is much better. Constant and good enough alrorithm receive the same measurement of quality. 

Minimum value

Ok, so let's throw away average value, and instead try optimization minimum value. Like in this forumla:

M = min(precision, recall)

Then just empty chart will look like this:

as you can see on the picture, good algorithms will be concentrated in top right corner. And the worse algorithms will be closer to left bottom part. 

But still it doesn't perform as well as we would like to. Consider two algorithms:

1.1.  precision 0.4

1.2. recall 0.5

1.3. M = 0.4

second one:

2.1. precision = 0.4

2.2. recall = 0.9

2.3. M = 0.4

They will look on chart like this:

so, it is clear that second alorithm is better because with the same precision it gives higher recall. But on chart it is located at lover place, closer to bottom. Also both algorithms lie on the same linve, while in reality it shoudn't be the case. 


One more idea can be to smooth those lines with help of garmonic average, which is also named F-Measure. It has following formula:

Quite often β is assigned value 1. In that case F-measure look like this:

β plays a role of weight for precision ( in other words importance of precision ).

Consider two algorithms:


  1. precision = 0.4
  2. recall = 0.5
  3. F = 0.44


  1. precision = 0.4
  2. recall = 0.9
  3. F = 0.55

and how they look at chart:

so you can see that second algorithm is closer to right top corner or closer to ideal classifier. 

Let's come back to this formula:

Imagine following scenario. If you want to give priority to precision, what should be value of β ? Something bigger then 1. For example 2. 

If you want to give priority to recall, then β should be smaller then 1. For example 0.5. 

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Automation Shedule Screen Is Not Executed


Hello everybody,

today I want to describe interesting feature of Acumatica related to back ups of database. Imagine the following: you've restored database from back up at your dev environment. And let's say you have automation schedule that every hour you should send to each contact some emails. So, you've restored customization and would like to find the button that will block sending of all emails. At which screen it is? At none. It is interesting to know, that Acumatica already "pressed" at this button when you've restored db from back up. But for now you probably have another question. How to debug execute any schedule at all?

I propose following steps:

  1. Delete all automation schedules.
  2. Create new automation schedule just fory our screen.

Delete all automation schedules

That is relatively simple task. As one of the ways you can execute following sql:

UPDATE AUSchedule set DeletedDatabaseRecord = 1

After that your screen SM205030 ( aka Automation Schedules ) will look pretty lonely and orphaned, but your partners will not mark your mail server as spam after you initialize schedule

Create new schedule

  1. Navigate to screen SM205020
  2. Create schedule with usage of screen that you want to use

Come back to screen SM205030 and press at button Initialize Scheduler as presented at screenshot:

and after that you'll have opportunity to debug your screen. Take note that button Initialize scheduler can't be unpressed. 

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How To Modify Default Time Zone At Acumatica


Hello everybody,

today I want to make a short notice on how to change default time zone in Acumatica. 

In my case such need appeard when it was needed to modify default time zone of Acumatica that I've restored from database backup. In order to do this you'll need to go to screen that is named Site preferences. Id of that screen is sm200505. 

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Branch Restriction In Automation Schedule In Acumatica


Hello everybody,

today I want to describe one behaviour of Acumatica processing screen. 

So, once upon a time I created processing screen. Purpose of that screen was simple: take data from some external source and insert it into Acumatica. 

As that processing screen worked fine, it was taken a decision to create automation schedule step that will make that screen to be executed by Acumatica automatically. And then following issue arised: also that screen worked great in manual mode, it didn't work at all in Automation schedule mode at all. 

After long investigation I found the following:

  1. Automation screens are executed from the user acount admin
  2. Also admin should have access to everything, that is not always the case with Acumatica. In my case admin account didn't have access to branches.

As result, nothing was imported. So, what was solution to that issue? Change scope to PXReadBranchRestrictedScope like this:

                var thr = new Thread(
                    () =>
                        using (new PXReadBranchRestrictedScope())
                            var portionsCustomers = customers.Skip(a * sizeOfOneChunk).Take(sizeOfOneChunk).ToList();

as soon, as I've applied PXReadBranchRestrictionScope life become easier, and data started to flow into Acumatica at automation schedule also. If to speak particularly about PXReadBranchRestrictionScope, it has following purpose: remove restriction by branch, that is automatically applied by default to current user. 

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How Helping Others Can Transform Your Life


Here in Ukraine there is a joke: nothing spoils health of Ukrainian more then richness and welfare of his neighbor.

Also I often hear statement that helping others can transform your life to better. I've spent some time on finding the ways to help others. But helping not via giving money. As one man once said give somebody fish for two times and for third time that person will demand fish from you. So I wanted to be a person that can give fishing rod to people instead of just giving them fish.

As result I've decided to teach some close friends of mine programming. Well, it is not a surprise because I'm quite skillful in that area and what else can I teach? And you know, it changed my life to something that I never expected.

Lesson 1. Obedience

My first student was George. As usually I don't like to deal with relatives of my friends if I don't know them personally, but I decided not to be dogmatic and decided to give a try. George was very initiative and smart guy and one of his decisions was to go to programming courses. That was really good decision, and he learned plenty of staff in C#, as well as in html, CSS, Javascript. After he passed those courses I've made him job interview and decided to help him with landing of the job. It was first time in my life when I heard that for somebody lack of specialized diploma can be missing part. Not big minus, but something that person good to have if he doesn't have specialized education. I didn't ask George to go for degree, but decided to help him and gave him single recommendation: participate in development of some open source tool. I supposed that such kind of activity can help him to get needed experience. Meanwhile I myself started to search for some job that I can give to him. With time I found one guy at upwork that was willing to cooperate with both of us. So I was very happy, and asked George to make html/css markup exactly in solution, and myself started to program tricky C# part. And you know what? Every day I've asked George about results, he reported to me about good progress that he've made and our cooperation pretended to bring good results until.... Until I found that George just created html page instead of putting it according to way that I've asked him. As result missed deadline, negative impression about me on upwork and lesson #1:

  1. Obey to your mentor or superior even if you sure that you know better.

After that story I've never did something against what Team Lead told me to do until I've discussed with him my idea. I learned this lesson because I've seen how bad it is to say yes, I will do as you say and then do something similar to what you've said, but not exactly as agreed. Interesting that George finally become software developer, but it took him 5 years. So one more tiny lesson: commitment can bring you good result.

Lesson 2. It is hard to become a programmer.

My second student was another friend that for me looked as very gifted person. Let's name him John. He didn't have money to go on courses of programming, so I organized for him pluralsight subscription and made bi-weekly monitoring of his progress. And I can say the following: John is really gifted person, but not in programming, but in selling. After few months of training I've noticed that John could convince me that he really knows and understands parts of C#, but only after deeper analysis I was able to see that it wasn't the case. On the example of John I've realized that John can sell to viper it's own poison with some discount and viper will be happy. After that I've recommended to John to work for companies as sales manager. And you know what? He gets promotion after promotion as sales manager. I'd with to be as good in programming as John in selling. Most surprising part for me is that John almost didn't have any courses on how to do sales. While for programming he spent plenty big amount of time but he is really brilliant sales manager. So lesson 2:

Some people need much more time to become programmers

Lesson 3. Mentor can make mistakes, but allow him to fix them.

My third student was one more friend, let's name him Michael. Michael was probably the most obedient student that I ever had. What was the most impressive to me, that Michael had plenty of disappointments. For him it was really hard to learn programming. He had issues with understanding what is array, what is collection, what is class. Why on earth they are needed, why object oriented programming is needed, etc. Some time I become so exhausted from explaining him what to do that I've sometime had desire to give up. But luckily I and Michael didn't. After half of year Michael had his first job interview that he failed. Try to guess, why? Because he was good in understanding of language, but he was very bad in application of language. He weren't able to reverse string in C#. And that was mine error as well. I so much concentrated on training Michael with theory, that I've ignored main purpose of programming language: programming steps. As result after Michael's fail I've made a change to his program and added much more coding practice. It is worthy to mention that Michael now works as software developer to. So lesson 3:

Mentor can make mistakes and will make them, but allow to mentor fix mistakes.


I have little bit more mentoring students then three mentioned in this article, but just want to say the following:

  1. If you will help somebody to become a programmer, you yourself will become better programmer
  2. Our brain works differently when you try to understand something and when you explain it to somebody
  3. If you search for mentor keep in mind that he can make mistakes in you, but still he knows better in case if he is working programmer

I hope this article will inspire already working programmers to stretch helping arms to other people that want to enter software development industry as well as inspire those who search for helping arm realize that such hand can really exist.

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How To Measure Quality Of Learning Part 2


Hello everybody,

today I want to add few more notes about measuring of quality of learning, but today about tasks of classification. 

So, one of the ways can be measuring number of wrong answers. For example with usage of the following formula:

Imagine that your classification set has three possible labels: a (10 elements ), b ( 15 elements ), c ( 20 elements ). And let's say that your model wrongly classified 2 out of a, 3 out of b and 4 out of c. In that case following formula is applicable:

Historically it happend that in classification tasks it is common to maximaze function, while in regression learning vice versa. 

Another common measurement of quality of classification is accuracy. Formula is like this:

That is very simple measuremnt of quality, and it is widely used. But it has some side effects. Let's consider few examples.

Unbalanced samplings

Consider following example. Let's say you have 1000 elements in sampling. And in your sampling 950 elements belong to class a, and 50 elements belong to class b. And let's say you've built a model that gives as output always class a. That model is useless, because it doesn't reproduce anything in data. But accuracy of that constant algorithm will be 0.95. But let's say you still want to use accuracy for measurement. What kind of output can be considered as reasonable? In our sample accuracy should be in range [0.95, 1], and not [0.5, 1] as in case of binary classification. 

Consider another example. Let's say you want to build a model which will give advice: to give loan or not to give a loan. And lets say you have two models:

Model 1:

  • 80 loans returned
  • 20 loans not returned

Model 2:

  • 48 loans returned
  • 2 loans not returned

Which model is better? What is worse? Give loan to bad customer, that will not return loan, or not give loan to good customer that can return loan? Looks like littlbe bit more characteristics are needed. Accuracy doesn't take into account value of error. Something more is needed to be taken into account. Also adding of precision allows us not to treat all objects as elements of one class, because in that case we will get increase of False Positive.

Error matrix

Consider following error matrix:

  y = 1 (belongs to class 1) y = -1 ( belongs to class 2 )
a(x) = 1

True Positive (TP)

Correct trigering

False Positive (FP)

Wrong triggering

a(x) = -1

False Negative (FN)

Incorrect skipping

True Negative (TN)

Correct skipping

So, we have two columns: y=1 and y=-1. In case if model treat element as something belonging to y=1 we can say that model worked. If modle treat element as belonging to y = -1 we can say that model skipped element. In such a way we have two kinds of errors: inoccrect triggering and wrong skipping. 

Consider then following example. Let's say we have 200 objects: 100 belongs to class 1 and another 100 belongs to class -1. And take a look at following confusion matrixes:

Model 1:

  y = 1 y = -1
a1(x) = 1 80 20
a1(x) = -1 20 80

Model 2:

  y = 1 y = -1
a2(x) = 1 48 2
a2(x) = -1 52 98

And question: which one is better? Model 1 or model 2?

For such purposes we can use two characteristics: precision and recall. For me personally recall can be also characteristics of completeness of memorization.

Formula for precision:

and for recall:

now if to put those values into calculation we'll receive the following:

precision(a1,x) = 0.8

recall(a1,x) = 0.8

precision(a2,x) = 0.96

recall(a2,x) = 0.48

From those standpoint we see that second model is more precise but with sacrifice of recall. In other words if second model triggered we can be sure with bigger degree of confidence in correctness of it's result. Or in another words you can interpret precision as part of objects that classifier interpret as positive and they are really positive, while recall says to you which part of objects of class 1 model really found.

How to use precision and recall?

And now what? How can you use precision and recall? For example like this. You have a task of loan scoring. It can sound like: un returned loans number should be smaller then 5%. It terms of todays formula it looks like:

precision(a, X) ≥ 0.95. And your task is to maximize recall. 

Another example. You should fine not less then 80% of sick people in some set. In terms of formulas it look like this:

recall(a, X) ≥ 0.8 , and you maximize precision.

Unbalanced sampling

  y = 1 y = -1
a(x) = 1 10 20
a(x) = -1 90 1000

imagine that you've get result as displayed in table above. It has wonderful accuracy: 

accuracy(a, x) = 0.9

but precision and recall help you to see real picture:

precision(a, x) = 0.33

recall (a, x) = 0.1

Should you use this model? Definetely not!!!

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Coefficient Of Determination


Hello everybody,

Today I want to describe some ideas about measure quality of learning. 

First of all I want to point areas where you can apply those measurements. It can be in three areas:

  1. For setting funtional during learning
  2. For picking hyperparameters
  3. For evaluation of ready made model

Another way can be combination. You can measure quality during learning with one measurement, but final model you can analyze with other measurement. 


So, let's start with most common formula: mean squared error:

In words it reads the following: difference between prognozed value and desired value, squared, summed and finally averaged. 

MSE has following featues:

  1. Easily minimizable
  2. Punishes stronger for bigger mistakes

What it means in practice? If your learning data set has many anomalies, then MSE is definetely not a point to apply. But if your data is without anomalies then MSE is really good choice. Because MSE will learn anomalies. And you don't want your model to learn anomalies, right?


Another point of choice for data scientists is mean averaged error:

In words it is averaged module of difference between desired output and actual output.

It has following features:

  1. Harder to minimize
  2. Less punishes for bigger mistakes

In practice it means that if your learning set has plenty of anomalies then MAE is one of the functions to consider.

Coefficient of detemination

Means squared error has interesting modification, coefficient of determination. Take a look at formula:

where  is average answer value

The main part of coefficient is fracition, in which numerator has sum of squared deviations, while denominator has sum of deviations of answers. 

So, what coefficient of determination explains? It explains which part of dispersion is explained or modeled in whole dispersion of answers. It's value is also interpretable. 

It has following features:

For workable models coefficient of detemrnation is between zero and 1. 

If coefficient of detemrnation is equal to 1 then we built ideal model.

If coefficient of detemrnation is equal to zero, then model is like constant value

If coefficient of detemrnation is smaller then zero then model is worse then constant value.

Asymetric error

Consider following scenario. You are owner of shop that sells laptops. And you have following question mark for yourselves: what amount of laptops to preorder. Another question mark that you get is maybe it's better to have little bit more laptops then needed? For such a cases maybe you can consider stronger punishment for under forecast then over forecast. One of the example of functions that can be used is quantile error. Take a look at formula:

It looks pretty complicated, so let's go in some details of it.

Parameter τ ∈ [0, 1] defines for what to punish stronger: for over forecast or under forecast. 

If τ is closer to 1 then model will be punished for under forecaset, otherwise for over forecast. 

If this formula looks complicated below goes visual explanation:


step #1 calculate difference between desired output and model output

step #2 choose multiplier

step #3 in case of under forecast we multiply by τ - 1 and summ it. In case of over forecast multiply on τ.

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Invokeifrequired Template


Hello everybody,

today I want to document simple but very useful feature if you work with multiple threads in Winforms application. 

Quite often it happens that you execute in some paralel thread long running calculations and would like time from the time notify results to UI. 

But if you try to do this then you'll get an error that will say to you that parallel thread doesn't have permissions to some control because it didn't create such a control. So, how then update UI?

The answer is simple, you should use method Invoke of the control. In that case everything inside of method Invoke will be executed from UI thread. 

Needless to say that such approach is workable but to some degree cumbersome. So in order to simplify life I've created following extension method:

public static class Extensions
    public static void InvokeIfRequired(this ISynchronizeInvoke obj, MethodInvoker action)
        if (obj.InvokeRequired)
            var args = new object[0];
            obj.Invoke(action, args);

And then in order to update text box field following logic was enough:

txtLog.InvokeIfRequired(() =>
    txtLog.Text += "\r\n check following id SubAccount: " + foundItem.RowId;

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Different Types Of Search In Acumatica


Hello everybody,

recently friend of mine gave me wonderful question:

In PXSelect command, I saw Search, Search2, Search3… keywords, please explain the difference.

Thats really good question which shows his attentiveness to details.

So, no let's go part by part.


First of all, Search statement can be applied to those kinds of attributes: PXSelector, PXDbScalar and PXDefault. 

Also you can apply Search statement to cases when you updated something in cache of Acumatica and what to reopen that part. It can look like this:

Document.Search<POOrder.orderNbr>(currentPoOrder.OrderNbr, currentPoOrder.OrderType);

or like this:

[PXDefault(typeof (Search<Company.baseCuryID>))]

Don't mix attribute use with search in graph. The first form you can use in your methods, while second you can use in DAC class. 

As attributes

If to speak about attributes Search allows you to set specific value of of field in your DAC class. In other words it selects exact field rather then a record. The field specification goes as paramter. If to speak about syntax it is identical to PXSelect.

Following search options exist:

Type of search Description
Search<Field> Gets field value
Search<Field, Where> Gets field value with filtering by Where condition
Search<Field, Where, OrderBy> Gets field value with filtering by Where condition and ordering
Search2<Field, Join> Gets field value with filtering by using Joins with other tables
Search2<Field, Join, Where> Gets field value with filtering by using Joins with other tables and applying where condition
Search2<Field, Join, Where, OrderBy> Gets field value with filtering by using Joins with other tables and applying where condition and ordering
Search3<Field, OrderBy> Gets field with ordering application
Search3<Field, Join, OrderBy> Gets field value with joins and order by application
Search4<Field, Aggregate> Gets aggregated field value
Search4<Field, Where, Aggregate> Gets aggregated field value with filtering by where condition
Search4<Field, Where, Aggregate, OrderBy> Gets field value with filtering by where, aggregation and order by
Search5<Field, Join, Aggregate> Gets field value fiwth application of joins and aggregateds
Search5<Field, Join, Where, Aggregate> Gets field value with application of joins and where and aggregate
Search5<Field, Join, Where, Aggregate> Gets field value based on join, where and aggregate condition
Search6<Field, Aggregate, OrderBy> Gets field value based Aggregate and order by
Search6<Field, Join, Aggregate, OrderBy> Gets field value based on join, aggregate and order by
Coalesce<Search1, Search2> Gets field value with using Search1 or if Search1 gives null uses Search2

I hope with this table you can now better understand which search to use



  • Dmitrey Makarov-Paton said

    Thanks, Yuriy, great post. Please post more. Pls, can you clarify one thing though?

    Case 1. (DataView.Search) Does the query executed against the database every time or it searches the caches first? What happens on the consecutive calls to the search.

    Case 2.
    Does the query executed when the item inserted into the cache only.? What happens on the consecutive calls also. Does the cache of the type specified is searched?

  • docotor said

    Hello Dmitrey,
    for case 1 queries will be executed first time against db, other times if possible against cache in order to minimize load on db.
    For case 2.I'm not sure that I understand it. Can you please add a bit more description to your question

  • Dmitrey said

    Hi Yuriy, thank you for answering. I'm observing a different behaviour though. Perhaps you can spot an issue. Please see my contrived example below. My observations as follows...
    1. DataView.Search always executes SELECT TOP(1) ... for a new key value. Regardless, where there items of this type in the cache.
    2. Same behaviour for Search in PXDefault

    Please try the code below. Set up SQL PROFILER to for RPC:Competed & SQL:BatchCompleted events.
    Thanks. Keep up with your awesome posts.

    public class DataContext : PXGraph<DataContext>, IDisposable {

    public PXSelect<PriceList> PriceList;
    public PXSelect<ParkingLot> ParkingLots;

    public void Init() {

    public void Dispose() => this.Clear();
    public ParkingLot CreateParkingLot() => (ParkingLot)ParkingLots.Cache.CreateInstance();

    public class Test {

    public void DoThings1() {

    using (DataContext dc = PXGraph.CreateInstance<DataContext>()) {
    dc.Init(); // Select all prices

    int parkingLotId = 2;
    dc.ParkingLots.Select(); // Database is quired, how many records you have in db now in cache
    ParkingLot item = dc.ParkingLots.Cache.Cached.Cast<ParkingLot>().FirstOrDefault(row => row.ParkingLotID == parkingLotId);
    Debug.Assert(item != null, "Must in the cache");
    dc.ParkingLots.SetValueExt<ParkingLot.grade>(item, "B"); // Your other example! item's status does not change to Updated!!

    var instance1 = (ParkingLot) dc.ParkingLots.Search<ParkingLot.parkingLotID>(parkingLotId); // Database queried again. SELECT TOP(1) ... WHERE ID=1
    Debug.Assert(Object.ReferenceEquals(instance1, item), "Same");
    Debug.Assert(instance1.ParkingLotID == item.ParkingLotID, "Same");

    var instance2 = (ParkingLot) dc.ParkingLots.Search<ParkingLot.parkingLotID>(parkingLotId); // 2nd call, Database NOT queried here unless you change ID to 2.
    Debug.Assert(Object.ReferenceEquals(instance1, instance2), "Same");

    var instance3 = dc.ParkingLots.Insert(dc.CreateParkingLot().With(r => r.Grade = "C")); // Triggers query on pxdefault
    Debug.Assert(Decimal.Compare(instance3.PricePerDay.Value, 5) == 0);

    var instance4 = dc.ParkingLots.Insert(dc.CreateParkingLot().With(r => r.Grade = "B")); // Triggers query on pxdefault
    Debug.Assert(Decimal.Compare(instance4.PricePerDay.Value, 10) == 0);

    public class PriceList : IBqlTable {
    public abstract class grade : IBqlField { }
    [PXDBString(1, IsKey = true)]
    public string Grade { get; set; }

    public abstract class price : IBqlField { }
    public decimal? Price { get; set; }

    /// <summary>
    /// </summary>
    public class ParkingLot : IBqlTable {
    public abstract class parkingLotID : IBqlField {}
    [PXDBIdentity(IsKey = true)]
    [PXUIField(DisplayName = "ID", Enabled = false, Visible = false)]
    public virtual int? ParkingLotID { get; set; }

    public abstract class grade : IBqlField { }
    [PXDBString(1, IsFixed = true)]
    public virtual string Grade { get; set; }

    public abstract class pricePerDay : IBqlField { }
    [PXDefault(typeof(Search<PriceList.price, Where<PriceList.grade, Equal<Current<ParkingLot.grade>>>>))]
    public virtual decimal? PricePerDay { get; set; }

    create table [dbo].[PriceList](
    [Grade] [nchar](1) NOT NULL PRIMARY KEY,
    [Price] [decimal](18, 2) NOT NULL,

    create table [dbo].[ParkingLot](
    [ParkingLotID] [int] IDENTITY(1,1) NOT NULL primary key,
    [Grade] [nchar](1) NULL,
    [PricePerDay] [decimal](18, 2) NULL,

  • docotor said

    Hi Dmitrey,
    thanks for valuable test and comment. You are right.

  • docotor said

    Just want to add. The query that always execute against database are PXSelectReadOnly and it's modifications. Other kind of queries can execute against db, but also can omit db, and read everything from cache or part from cache and part from db.

  • Dmitrey Makarov-Paton said

    Thanks Yuri. Where do you work? What's your skype/email?

  • docotor said

    My skype is zaletskiy. For now I work as remote contractor and I mainly specialize on Acumaitca extending. I've send you an email message also.

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Update Database Error On Switching From Net Core 1 1 To 2 0


Hello everybody,

today I want to share some strange behaviour that I faced. 

Recently I needed to switch from .Net core 1.1 web app to .Net core 2.0 app. 

I found over internet that simplest way to achieve it will be just opening project in Visual Studio 2017 and VS will switch your project by itself. I decided to give to such attempt a try. 

Initially all went fine. Visual Studio 2017 gave me very nice looking report which convinced me that life is easy and wonderful. Actually it said that project was switched to .Net core 2.0 with success.

Then I've tried to execute in package manager console Update-Database command. Unfortunately I've seen following error message:

An error occurred while calling method 'ConfigureServices' on startup class 'Startup'. Consider using IDbContextFactory to override the initialization of the DbContext at design-time. Error: This method could not find a user secret ID because the application's entry assembly is not set. Try using the ".AddUserSecrets(string userSecretsId)" or ".AddUserSecrets<TStartup>()" method instead.
No parameterless constructor was found on 'ApplicationDbContext'. Either add a parameterless constructor to 'ApplicationDbContext' or add an implementation of 'IDbContextFactory<ApplicationDbContext>' in the same assembly as 'ApplicationDbContext'.

After some research I found following proposal to apply:

instead of line 


use line 


and for my suprise Update-Database reported to me that it was successful. 

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