I have been attempting to research the best way to do the following:
Save a user-defined text based expression to a database which outlines content to be displayed on a page.
example: "The employment status of this person is a [employment] employee, [hours] hrs a week."
Where [employment], [hours] correspond to a key/value in a database
example:
TABLE
ID KEY VALUE
1 employment casual
1 hours 10
2 employment parttime
2 hours 25
At runtime a page where this user-defined expression would be used for display has access to a persons id and would need to collect the relevant details from the database, parse and replace the [employment], [hours] placeholders with the retrieved data.
example: "The employment status of this person is a casual employee, 10 hrs a week.
The solution I am looking for needs to be dynamic enough to handle a user entering any static text in and around any number of placeholders.
EDIT to clarify my meaning:
There will be a settings area where the user can enter the expression they want
displayed on the screen, which could be any text containing any 'key' values from
the database. Different users will see their own defined expression displayed.
another example: "The employee works [hours] hrs, [employment]"
would display as: "The employee works 10 hrs, casual"
I'm either not doing very well with my searching or just not understanding the results very well. I have found a lot of information regarding CustomExpressionBuilder, Lambda expressions, Expression trees, etc. and I am getting confused whether any of these are the right track for what I need to do. Perhaps I'm just not there yet on my understanding being new to this!
If I can get this working I would also love to be able to add some simple ternary type functionality and/or mathematical functionality. It seems like there is library called NCalc that would make this quite simple, but I could not see an example of the text replacement requirement that I initially need, or immediately see a way to tweak it to work.
Thanks for any advice, and I am more than happy to research further but need a little push in the right direction.
From your question, it's a bit vague as to how far you've gotten with this problem, ie if you are already able to retrieve all of the values from the database or not.
If you are simply trying to build a string expression as you mentioned above, once you have the values above, I would probably use either String.Format or perhaps a string builder.
For example, if we presume that you have the values out of the database and they are contained within properties on a Person class (just as an example), you could write something to the effect of:
var message = String.Format("The employment status of this person is a {0} employee, {1} hrs a week.", person.Employment, person.Hours);
Like I said, it's a bit vague from your question exactly where your issue is, but if you're just looking to build that one particular expression once you have the values, the above would work. You can replace the person.Employment and person.Hours arguments with the appropriate values once you have those out of the database.
Related
I'm currently trying to implement a table within my SQL database. I'm looking to create a table that can be used to check if a user on my website has liked a post. The idea is to have a table with one axes iterating the posts on the website and one axis with the userID values iterated. Then in each box hold a binary value as to whether they have liked it. I'm just wondering how I would implement this. I have been doing this in C# by creating classes and converting these into server side code using Entity Framework 6.4.0.
Any help would be great.
What you are suggesting is a normalized structure for your use case; it would, for example, require adding more columns to the table everytime a post is added to the database (or a user, depending on whether you use rows or columns).
A typical database solution would be a bridge table, that represents the many to many relationship between posts and users.
Say table user_like_posts, with the following columns:
user_id -- foreign key to the "users" table
post_id -- foreign key to the "posts" table
You may want to add additional columns to the bridge table, like the timestamp when the user liked the post, or the-like.
Will every user have an opinion on every post? If not then you don't have the data you described. If users and posts are not related one to one then you have a simple relation. For each post that a user likes (or dislikes?) there is an entry for that user:
Likes/Dislikes Table:
User identifier
Post identifier
The binary value that indicates like or dislike
If the table only indicates 'likes' then you don't need the last column.
A design like this would work even if every user and every post is in this table. The table might get large in a hurry and keep growing every time you introduced a new post. But if this table only includes actual 'likes' (and/or 'dislikes') it should be manageable.
For a class you just have an enumerable that has the posts 'liked' (and possibly another that indicates the posts 'disliked.')
Think about what you are trying to represent. Ask yourself questions. Don't just latch on to an idea and try to 'do' it.
Will every user have an opinion of every post?
Do you need to store both 'likes' and 'dislikes?'
Can there be a 'neutral' opinion on a post?
Can users change their opinions?
You can only discover the correct data structure by asking and answering all the questions that matter to your situation (my list is not exhaustive - it is only an example.)
I am writing a report in C# that will generate an SQL statement to call data in SAP. In SAP ABAP, there is a command "SELECT-OPTIONS" which will automatically place on a screen a field which automatically has a number of different options to input data. For example, if you wanted to query a customer master database, you could enter a single customer number, multiple customer numbers, multiple ranges of customer numbers. Set criteria to include the customer numbers, exclude them, etc.
It is really nice functionality that users are asking me to duplicate but with a C# front end.
I am trying to replicate this a portion of this functionality by using lookup buttons, datagridviews, internal lists, etc.
I was wondering if anyone has done anything similar or if there is a customer class that already exists that does the equivalent.
You probably need to understand SAP ABAP and C# to fully understand the question as it is hard to explain without having to show a lot pictures and using a lot of words.
Thanks
Stephen
Most likely there is no generic finished product that will do it. In ABAP, this relies on the fact that select-options is bound to a variable, data element and domain, which, in turn, has either a valid-values-list (fix or via table) and/or various search helps. So if you need to enter an employee number, you will be able to select the number by name or by email or by department or other criteria. So basically, for each “type of object” that you want to enter there is some sort of input help that has intrinsic knowledge of entered data.
If you are only interested in an “input field” that is able to select an arbitrary number of following inputs at the same time (without value help dialogs)
include/exclude single values
include/exclude range (for sortable values) (42-50 or Bob-Mike)
include/exclude open ranges (>= 42)
include/exclude values by pattern (ash*)
Then: I never saw anything like that in any UI other than SAPs DynPro or WebDynpro.
In the end, you end up with a so-called range table, which has four values per line:
include/exclude
operation (equals, not equals, less than, between, etc)
value1
value2 (only relevant for operations like “between”)
So if you build a UI for that, the user will need to enter something which will end up in this construct.
Try ERPConnect from Theobald Software:
https://theobald-software.com/en/erpconnect/
I didn't find a mention of SELECT-OPTION control in the brochures but they claim they have .Net API for core SAP/ABAP tools and interfaces, so you can give a try.
I'm creating a database where users can enter some Error Reports and we can view them. I'm making these database with C# in the ASP MVC 3 .NET framework (as the tags imply). Each Error Report has a unique ID, dubbed ReportId, thus none of them are stored under the same Id. However, whenever a User creates a new Error, I pass their User Name and store it in with the rest of the report (I use User.Identity.Name.ToString() to get their name and store it as a string). I know how to get a single item from the data using a lambda expression, like so:
db.DBSetName.Single(g => g.Name == genre)
The above code is based on an MVC 3 tutorial (The Movie Store one) provided by ASP. This was how they taught me how to do it.
My major question is: is there a member function like the .Single one that will parse through the whole database and only output database entries whose stored User Name matches that of the currently logged in user's? Then, I can use this to restrict User's to being only able to edit their own entries, since only their entries would be passed to the User's View.
What would be the best way to implement this? Since the ReportId will not be changed, a new data structure can be created to store the user's Errors and passed through to the Index (or Home) View of that particular controller. From there they should be able to click any edit link, which will pass the stored ReportId back to the Edit Action of this particular controller, which can then search the entire database for it. Am I right in assuming this would work? And would this be ideal, given that the other items in the database are NOT passed through to the Index in this method, meaning the User does not have access to the other items' ReportId's, which the user needs to pass into the Edit Action for it to work? If this is ideal, this is the method that requires me to know how to parse through a database and grab every element that fits a particular description (stored User Name matches User's current User Name).
Or would a better approach be to pass the whole database to the Index View and only output the database entries that have User Name values that match the current logged in user's? I guess this could be done in a foreach loop with a nested if loop, like so:
#foreach(var item in db.Reports)
{
if(item.UserName == User.Identity.Name.ToString())
{
...code to output table...
}
}
But this passes the whole database which gives the user a lot more info than they need. It also gives them potential access to info I don't want them to have. However, I don't have to make a new data structure or database, which should lower server memory usage and fetch time, right? Or are databases passed by copy? If so, this method seems kinda dumb. However, I don't know if the first method would fracture the database potentially, this one certainly would not. Also don't remember if I NEED an else statement in C#, I'm more familiar with C++, where you don't need one and you also don't need {}'s for single line if's, if I need one: please don't judge me too harshly on it!
Small note: I am using CRUD Controllers made with the Entity First Framework in order to edit my database. As such, all creation, reading, updating, and deletion code has been provided for me. I have chosen not to add such basic, common code. If it is needed, I can add it. I will add what the Edit Action looks like:
public ActionResult Edit(string id)
{
Report report = db.Reports.Find(id);
return View(report);
}
It accepts a string as an id, ReportId is the id used and it IS a string. It is a randomly generated GUID string made with the GUID.NewGuid().ToString() function. I will also be doing the comparison of names with:
Model.UserName == User.Identity.Name.ToString()
Which was shown earlier. Sorry if this is too much text, I wanted to provide as much info as possible and not make anyone mad. If more info is needed, it can certainly be provided. So at the end of the post, the major question actually comes down to: which of the above two methods is best? And, if it's the first one, how do I implement something like that?
Thanks for your help!
Unless I'm completely misunderstanding you, you just want .Where()
Like this:
var reports = db.Reports.Where(r => r.genre == inputGenre);
This would get you an IEnumerable of Report, which you could then use however you wish.
I am working on program that calculate the GPAs for university students in C#.
I have made a gridview that contains columns for each subject. Its mark as letter and
number. After the user "student" insert his/her subject I want to let the user click a
button that will get the mark and the number of the credit hours of each subject. Calculate the GPA for the student and put the result in a textbox.
I am having trouble getting started. Any advice for a good place to start?
To answer just the question in your title:
To get value from the current row, first capture the row:
DataGridViewRow r = MyDataGridView.CurrentRow;
To get the value from cell 0:
string v = (string)r.Cells[0].Value;
What I see from your question you are having difficulty how to put the requirement in one place.
I'm assuming you already have the user requirements (it looks very simple) and I give basic steps you go through, it is not accurate and it doesn't fit for all type of projects, but your case is very simple and I think it is enough to do the work.
first you will need to create a flow, the steps the user will go through to accomplish the process.
then you will need the basic interface to let you have at least to know what controls you will need.
after that you will make the data structure (mostly the database schema) to know how the data will be stored and related to each other.
then you will create the business logic to implement your requirements.(the coding part)
and Last you will glue all the things and attach the code that wrote to the events in the interface based on the flow you made it at the first step.
I hope this helps.
I'm not sure about what you are trying to do, but you can take a look here:
http://www.c-sharpcorner.com/Articles/ArticleListing.aspx?SectionID=1&SubSectionID=191
I've solved lots of my WPF dumb design problems with these articles :P
I am writing a program that generates a single large table of information. The table is made up of two types of columns, columns that contain quantities, and columns that contain properties. Quantities are numeric values that can be summed, properties are qualitative values that attribute the quantity values.
If the data is in a table in a database I can write a query that selects specific properties and quantities and sums the quantities that have the same value for the selected properties.
Example:
Table:
Quanity1 Quanity2 Quanity3 Property1 Property2 Property3
12 43 12 RED Long Rough
43 23 23 Blue Short Smooth
43 90 34 RED Fat Bumpy
Query:
SELECT sum(Quanity1), sum(Quanity2), Property1 FROM Table Group By Property1
Result:
Quanity1 Quanity2 Property1
43 23 Blue
55 133 Red
What I want to do is give the user a graphical interface to do this with out knowing how to write SQL queries, or any code for that matter. Such as a set of list boxes where they select the properties and quantities they want to view and a table is displayed that shows the selected fields with the quantities summed. I may also later want to add the ability for the user to perform other SQL query like actions such as filtering based on certain conditions. Also I know later I'll need to be able to generate nice looking reports based on these user Queries.
I'm very new to ADO and .NET in general. But I'm thinking the best way to do this is to export my data into a System.Data.DataTable and then create an interface for the user to create a System.Data.DataView by generating a string for it's RowFilter property. Although, it's not obvious to me how I can not only filter and sort a DataTable but generate another Table or view that only contains specific columns from the big master table.
Overall does this sound like the best option, or is there another method I should consider? Does anyone have any specific tips or suggestions on how I should implement this? I was also questioning if any of this would be made easier with LINQ.
Update
I appreciate the suggestion of using Access or other available tool, but it's really not an option. Access is way too complicated for users here to try to figure out, and much more then I actually need. I'd always leave Access as an option for advanced users. But I would still like to setup a basic querying feature where the user selects the columns they want and the software automatically creates the view/query that selects and sums the appropriate columns.
Aside from being to complex the other issue with Access is there are to many clicks between changing something in my data structure and seeing a change in a report. I don't want the user to have to change something, re-export to access, open another program, and then open the report to see the effect of their change.
Consider buying an off-the-shelf query tool rather than re-inventing the wheel. The cheapest one that could do this sort of thing is MS Access or MSQuery in Excel. More elaborately you could use Report Builder (if your database is based on SQL Server - it comes for free with this) or a third-party tool such as Business Objects or Brio.
If you can live without tight integration this is far easier than trying to build your own ad-hoc query tool.
I also strongly recommend off-the-shelf - especially early on. If it becomes apparent later on that the users really need you to write a custom solution, then by all means go for it. But this early on I don't think it will be worth the time and effort you will spend.