I am trying the devart ibdac components but I am having a little issue with the IBCTable component. On tables with autoinc (trigger based) when I try to post the data it says that the field with the autoincrement must have a value, whereas if I use a SQL query to insert it everything works fine.
Is there any workaround for this?
You need to set the following properties for the TIBCTable component to automatically fill out the fields with values from the same generator / sequence that you use in your trigger:
GeneratorMode
GeneratorStep
KeyFields
KeyGenerator
For more information see the documentation of the TIBCTable component, you will find all the properties with links to the base class they are introduced in.
Related
My interface is very basic. It just includes edits for the user to input data into a database, when they click the button i want it to add the data into my database.
You can easily do this.
Go to the Data Controls tab of the Component palette.
Select a TDBEdit and place it on the same form as your DBNavigator. The IDE will name this DBEdit1
Set the Datasource property of your DBEdit1 to the same datasource as your DBNavigator.
Set the DataField property of DBEdit1 to the name of a field in your dataset.
Compile and run.
That's it. Leave your DBNavigator on your form because you will find that when you make a change to the contents of DBEdit1, its Save and Cancel buttons automatically enable to let you save or cancel the change.
Also, you'll find that if you click your DBNavigator's '+' button, which begins the insertion of a new record into your table, you can then type the field values for the new record into your DBEdits.
Don't use normal non-DB-aware TEdit components and a dynamically-created Sql statement which concatenates the TEdits's contents with other Sql as suggested in the other answer which briefly appeared here and now seems to have been deleted - it is a waste of time, but much more importantly renders your app vulnerable to Sql-Injection - see https://en.wikipedia.org/wiki/SQL_injection. By sending the server an unverified Sql statement which includes what the user has typed into a TEdit, you're effectively providing the user with an opportunity to type additional Sql statements into the TEdit and that is exactly how Sql injection can occur. On the other hand, when you use TDBEdits, the Sql for updating the database record is automatically generated by Delphi's TDataSet framework in a way which does not provide a similar opportunity for Sql Injection.
If some reason you absolutely have to generate your own Sql Update statements, to minimise the risk of Sql Injection, make sure that you use a parameterised Update statement, that is, one where the changed field values are specified as values of parameters in your TDataSet-descendant's Parameters object, rather than in the Update Sql itself. An example of a parameterised Update statement might be:
Update MyTable set FieldA =:FieldA, FieldB=:FieldB where RowID =:RowID
where :FieldA, :FieldB and :RowID are the parameters.
I can't find any info about this in the documentation, so I will ask here. How does breeze handle database column defaults? I have required columns in my database, but there are also default static values supplied for these in the database column definitions. Normally, I can insert null into these columns, and the new records will get the default. However, breeze doesn't seem to be aware of database column defaults, and the entities that have null in these columns fail validation on saving.
Thanks,
Mathias
Try editing the edmx xml by adding StoreGeneratedPattern = "Computed" attribute to the column with default value in the DB.
Edit:
Actually, before doing editing the xml, try setting the StoreGeneratedPattern property to Computed in the model editor itself.
Update:
This was fixed in Breeze 1.4.6 ( or later), available now.
Original Post:
There is currently in a bug in Breeze that should be fixed in the next release, out in about week. When this fix gets in then breeze will honor any defaultValues it finds in the EntityFramework data model.
One problem though is while it is easy to get 'defaultValues' into a Model First Entity Framework model via the properties editor, it's actually difficult to get it into a Code First EF model, unless you use fluent configuration. Unfortunately, EF ignores the [DefaultValue] attribute when constructing Code First model metadata.
One workaround that you can use now is to poke the 'defaultValue' directly onto any dataProperty. Something like:
var customerType = myEntityManager.metadataStore.getEntityType("Customer");
var fooProperty = customerType.getProperty("foo");
fooProperty.defaultValue = 123;
Did you ever try to create a ASP.NET MVC Project with Firebird database...I try it, and is difficult..
My problem:
I have working Firebird provider for Visual Studio 2010.
I have correct database with all needed for increasing the id of the tables.
I have created ASP.NET MVC 3 project, with included database, like EDMX file, with entities.
When i try to insert a record into a table, there occurs a problem that says:
FirebirdSql.Data.Common.IscException: violation of PRIMARY or UNIQUE KEY constraint "PK_USERS" on table "USERS"
That means the id of the record that is created is not increased.
I have stored procedures that must generate new id.
My question is:
How to insert record in Firebird data table from ASP.NET?
In Firebird you need to use triggers in combination with sequences (generators) if you want to have auto-increment like behavior. Otherwise you need to make sure that you assign a unique id yourself.
To create the sequence:
CREATE SEQUENCE mytable_id_sq;
To create a trigger for assigning a unique i (on a table called mytable)
set term !! ;
CREATE TRIGGER T1_BI FOR mytable
ACTIVE BEFORE INSERT POSITION 0
AS
BEGIN
if (NEW.ID is NULL) then NEW.ID = NEXT VALUE FOR mytable_id_sq;
END!!
set term ; !!
This trigger will only assign a generated value if no ID is assigned in the INSERT statement.
See also:
section SEQUENCE (GENERATOR) in the Firebird 2.5 Language Reference and How to create an autoincrement column? (this link talks about generators, the old name of sequences in Firebird).
Your EDMX isn't probably generated properly. Either you have to set the StoreGeneratedPattern manually or use http://blog.cincura.net/230841-generated-primary-key-in-entity-framework-model-from-firebird/ .
I have the following DBX structure in my software:
TSQLDataSet -> TDataSetProvider -> TClientDataSet
One of the fields from my TClientDataSet has the property Required set to false, because this field auto increments based on triggers and generators on the database (Firebird).
However, after configuring both TSQLDataSet and TClientDataSet with this field not being required, I'm getting really weird results when I try to read this field from my TClientDataSet. I suspect that I might need to do something extra to force my TClientDataSet to acquire the value of this field in this condition.
What am I missing here?
Thanks in advance.
EDIT
The help file for the Required property says something about this, but I couldn't quite understand what it want me to do.
Description
Specifies whether a nonblank value for a field is
required.
Use Required to find out if a field requires a value or if the field
can be blank.
If a field is created with the Fields editor, this property is set
based on the underlying table. Applications that set Required to true
for fields that must have values (for example, a password or part
number), but for which the underlying table does not require the
field, must write an OnValidate event handler to enforce the property.
When the Required property reflects a property of the underlying
database table, trying to post apply a null value causes an exception
to be raised. Applications that set the Required property to true when
the underlying table does not require the field, should raise an
EDatabaseError exception on null values in the OnValidate event
handler in order to achieve the same result.
EDIT 2
Forgot to mention: between the TDataSetProvider and the TClientDataSet, there is a DataSnap layer (the TClientDataSet connection is made with a DataSnap driver).
EDIT 3
I created a small test case with this DataSnap setup and it worked perfectly. The project is legacy, messy and I guess that either I have an obscure option configured somewhere that is biting me or I have stumbled in a DataSnap bug.
Haole, have you tried TClientDataset.RefreshRecord after inserting? Or even TClientDataset.Refresh?
Having generators, you can even get the generator in advance (before calling ApplyUpdates) in a query like select gen_id(generator,1) from RDB$Database (it's from memory, don't have Firebird here to test) and fill the PK field in advance.
EDIT: seems this is a heisenbug. I would try to remove the components and reconfigure them again from scratch (which means: after you remove, save and close Delphi).
Or even better, create an empty project with just that needed query configuration and try to view that data in a TDBGrid. If this problem still happens, maybe your FB installation have some component corrupted (or even Delphi installation)
Seems that the problem was an outdated field being read as an INTEGER and it was a SMALLINT in the database.
This problem was hard to debug and this question was misleading. Thanks for everyone that helped me debug this.
I have the challenge of needing to audit data changes made by users of an MVC application.
Auditing creation and deletion of records is easy.
Updates is proving to be the problem.
I'm looking for a way to automate this, but the problem I have is that the application is using stored procedures to bring back EF "complex types".
These are then used to build a view model, and after postback, the controller receives a new view model built from the form values passed back from the view. Therefore the original values are no longer available.
Does anyone have any suggestions for a secure way to keep the original values so they can be compared with the updated values, so that changes can be stored?
(I appreciate I could go back to the database for these, but is not efficient, and I would have to retain all the parameters to remake the same call, and find a way to automate that part of the process).
Have you tried an Audit Trigger using the INSERTED and DELETED tables.
http://weblogs.asp.net/jgalloway/archive/2008/01/27/adding-simple-trigger-based-auditing-to-your-sql-server-database.aspx
OR
In your stored procedures for insert,delete,update you can make use FOR XML AUTO. To get the XML for the record and add it to an audit table.
http://www.a2zdotnet.com/View.aspx?Id=71
UPDATE A T-SQL example
BEGIN
-- these tables would be in your database
DECLARE #table TABLE(ID INT IDENTITY(1,1) PRIMARY KEY, STR VARCHAR(10), DT DATETIME)
DECLARE #audit_table TABLE(AuditXML XML, Type VARCHAR(10), Time DATETIME)
-- this is defined at the top of your stored procedure
DECLARE #temp_table TABLE(PK INT)
-- your stored procedure will add an OUTPUT to the temp table
INSERT INTO #table
OUTPUT inserted.ID INTO #temp_table
VALUES ('test1', GetDate()),
('test2', GetDate() + 2)
-- at the end of your stored procedure update your audit table
INSERT INTO #audit_table
VALUES(
(
SELECT *
FROM #table
WHERE ID IN (SELECT PK FROM #temp_table)
FOR XML AUTO
),
'INSERTION',
GETDATE()
)
-- your audit table will have the record data
SELECT * FROM #audit_table
END
In the example above you could make temp_table a clone of table (have all of the columns from table) and in your OUTPUT clause use INSERTED.* INTO #temp_table, this would avoid have to reselect the records before getting the FOR XML AUTO. Another note, for stored procedures that do DELETE you would use DELETED.* instead of INSERTED.* in your OUTPUT.
If using SQL Server I recommend that you look into Change Data Capture (CDC).
It's an out of the box solution for auditing changes to the underlying tables of your application and it's relatively straightforward to set up, so there is no need for a custom solution that you then have to maintain.
If you have any supporting applications for your site, they'll also be covered and it also has the benefit of auditing any changes made directly against the database, such as from a DBA running a script.
Since your asp.net application may be running under one particular account, you'll probably need to add additional tracking information to capture the user who made the change. Fortunately this is also relatively straightforward. The following Stack Overflow question covers an approach to this using the ObjectStateManager
I was lookging for this myself, found this, check out Tracker for EF