I'm operating on a MySQL database using GORM v 2.0. I'm inserting row into database using GORM transaction (tx := db.Begin()). In previous GORM versions, Begin() returned sql.Tx object that allowed to use LastInsertId() method on query return parameter.
To do that in GORM v 2.0, i can simply call db.Last() function after insert row into database, or i can use smarter method?
Thank you.
In V2.0 the GetLastInsertId method was removed. As #rustyx says, the ID is populated in the model you pass the Create function. I wouldn't bother calling db.Last(&...) as this is a bit of a waste when the model will already have it.
type User struct {
gorm.Model
Name string
}
user1 := User{Name: "User One"}
_ = db.Transaction(func(tx *gorm.DB) error {
tx.Create(&user1)
return nil
})
// This is unnecessary
// db.Last(&user1)
fmt.Printf("User one ID: %d\n", user1.ID)
Related
I have this model with a custom JoinTable:
type Person struct {
ID int
Name string
Addresses []Address `gorm:"many2many:person_addresses;"`
}
type Address struct {
ID uint
Name string
}
type PersonAddress struct {
PersonID int
AddressID int
Home bool
CreatedAt time.Time
DeletedAt gorm.DeletedAt
}
How is it possible to assign a value to the Home field when creating a new Person?
Method 1
From what I can see in the docs, here's a clean way you might currently do this:
DB.SetupJoinTable(&Person{}, "Addresses", &PersonAddress{})
addr1 := Address{Name: "addr1"}
DB.Create(&addr1)
addr2 := Address{Name: "addr2"}
DB.Create(&addr2)
person := Person{Name: "jinzhu"}
DB.Create(&person)
// Add an association with default values (i.e. Home = false)
DB.Model(&person).Association("Addresses").Append(&addr1)
// Add an association with custom values
DB.Create(&PersonAddress{
PersonID: person.ID,
AddressID: addr2.ID,
Home: true,
})
Here we're using the actual join table model to insert a row with the values we want.
We can also filter queries for the association:
addr := Address{}
// Query association with filters on join table
DB.Where("person_addresses.home = true").
Model(&person).
Association("Addresses").
Find(&addr)
Method 2
Here's a more magical way, by (ab)using the Context to pass values to a BeforeSave hook, in addition to the SetupJoinTable code from above:
func (pa *PersonAddress) BeforeSave(tx *gorm.DB) error {
home, ok := tx.Statement.Context.Value("home").(bool)
if ok {
pa.Home = home
}
return nil
}
// ...
DB.WithContext(context.WithValue(context.Background(), "home", true)).
Model(&person).
Association("Addresses").
Append(&addr2)
This method feels icky to me, but it works.
As you can find this point in the official documents of the GROM, you can implement some methods for each table(struct).
You can implement BeforeCreate() and/or AfterCreate() methods for your join table, gorm will check that method on time!
You can do anything inside those methods to achieve your goal.
here you will find the full documentation.
enjoy ;)
I want to catch and handle SAPSQL_DATA_LOSS in my ABAP code.
I tried this:
try.
SELECT *
FROM (rtab_name) AS rtab
WHERE (sub_condition)
into table #<sub_result>
.
catch SAPSQL_DATA_LOSS into error.
...
endtry.
But above code is not valid. I get this message:
Type "SAPSQL_DATA_LOSS" is not valid
And I tried this:
catch SYSTEM-EXCEPTIONS SAPSQL_DATA_LOSS = 123.
SELECT *
...
.
endcatch.
if sy-subrc = 123.
...
endif.
But above code gives me:
Instead of "SAPSQL_DATA_LOSS" expected "system-exception" (translated from german to english by me)
How to catch SAPSQL_DATA_LOSS?
This question is not about "why does this exception happen?". This is already solved. My code should handle the exception.
SAPSQL_DATA_LOSS is a runtime error.
As SAPSQL_DATA_LOSS is not a class-based exception, it is not possible to catch it using try catch.
As SAPSQL_DATA_LOSS is not a catchable runtime error, it is not possible to catch it using try catch SYSTEM-EXCEPTIONS.
see the below catchable runtime errors.
https://help.sap.com/doc/abapdocu_751_index_htm/7.51/en-US/abenueb-abfb-sysexc.htm
After some tries I can propose you a possible solution.
This is a workaround:
I don't know if it can be applied to your case, since it needs the select statement to be wrapped into an RFC function module !
The main point is that a short dump (message type X) CAN be handled in RFC calls.
So using an RFC (CALL FUNCTION 'xxxxx' destination 'NONE' for example) and using special exception SYSTEM_FAILURE, the system does not terminate the caller program, but instead it returns a SY-SUBRC > 0 with the Short dump informations in system message fields (SY-MSGxx).
STEPS
Create a Function module (RFC enabled) with your select statement input + the row type of the result table. (All parameters passed by value)
You need this last parameter since generic tables can't be passed in RFC (no "TYPE ANY TABLE" allowed)
FUNCTION Z_DYN_SEL .
*"----------------------------------------------------------------------
*"*"Local interface:
*" IMPORTING
*" VALUE(RTAB_NAME) TYPE TABNAME16
*" VALUE(SUB_CONDITION) TYPE STRING
*" VALUE(RESULT_TYPE) TYPE STRING
*"----------------------------------------------------------------------
* RTAB_NAME: DB Table
* SUB_CONDITION: WHERE Condition
* RESULT_TYPE: The ROW type of the internal table
field-symbols <sub_result> type any table.
* DEFINE LOCAL DYNAMIC TABLE TO STORE THE RESULT
data: lr_res type ref to data.
create data lr_res type standard table of (result_type).
assign lr_res->* to <sub_result>.
* DYNAMIC SELECT
select *
from (rtab_name) as rtab
where (sub_condition)
into table #<sub_result>.
* EXPORT RESULT TO A MEMORY ID, SO IT CAN BE RETRIEVED BY CALLER
export res = <sub_result> to memory id 'RES'.
Main program:
In this caller example some parameters are passed to the RFC.
KTOKD field (should be 4 chars long) is passed with a char10 value (producing your short dump).
If ANY Dump is triggered inside the function, we can now handle it.
If everything went fine, IMPORT result from the EXPORT statement inside the RFC
field-symbols <sub_result> type any table.
data: lr_res type ref to data.
create data lr_res type standard table of KNA1.
assign lr_res->* to <sub_result>.
data lv_msg type char255.
call function 'Z_DYN_SEL' destination 'NONE'
exporting
rtab_name = 'KNA1'
sub_condition = `KTOKD = 'D001xxxxxx'`
result_type = 'KNA1'
exceptions
system_failure = 1 message lv_msg.
if sy-subrc = 0.
import res = <sub_result> from memory id 'RES'.
else.
write: / lv_msg.
write : / sy-msgid, sy-msgno, sy-msgty, sy-msgv1, sy-msgv2, sy-msgv3, sy-msgv4.
endif.
RESULTS
After the RFC call in case of a short dump in the select statement, the program is not terminated and the following pieces of information are available
SY-SUBRC = 1
lv_msg is the error text (Data was lost while copying a value.)
Sy-msgid = 00
Sy-msgno = '341'
Sy-msgty = 'X'
Sy-msgv1 = 'SAPSQL_DATA_LOSS'
I tried to implement the akka-http rest example provided at
https://github.com/ArchDev/akka-http-rest
but I'm stuck with the
slick.SlickException: This DBMS allows only a single column to be returned from an INSERT, and that column must be an AutoInc column.
at slick.jdbc.JdbcStatementBuilderComponent$JdbcCompiledInsert.buildReturnColumns(JdbcStatementBuilderComponent.scala:67)
Here is the Scala Code:
Signup API:
path("signUp") {
pathEndOrSingleSlash {
post {
entity(as[UsernamePasswordEmail]) { userEntity =>
complete(Created -> signUp(userEntity.username, userEntity.email, userEntity.password))
}
}
}
}
AuthService.scala
def signUp(login: String, email: String, password: String): Future[AuthToken] =
authDataStorage
.saveAuthData(AuthData(UUID.randomUUID().toString, login, email, password.sha256.hex))
.map(authData => encodeToken(authData.id))
AuthDataStorage.scala
...
override def saveAuthData(authData: AuthData): Future[AuthData] =
db.run((auth returning auth).insertOrUpdate(authData)).map(_ => authData)
...
Since I'm new to Scala and Slick, can anyway provide the information why this exception is occurring even though I've defined O.AutoInc in Model. I'm using MySQL RDBMS
The problem is with returning auth. Instead of returning auth i.e complete object, Just return the auto-increment Id id. Slick does not support returning the complete object, though it compiles correctly. It does not generate a valid sql query.
Once you can get access to the auto-increment id then you can build the AuthData using the argument of the function.
Code:
(auth returning auth.map(_.id)).insertOrUpdate(authData)).map(id => authData.copy(id = id))
The exception is the result of a MySQL behavior. As the Slick documentation states:
Many database systems only allow a single column to be returned which must be the table’s auto-incrementing primary key. If you ask for other columns a SlickException is thrown at runtime (unless the database actually supports it).
Change the saveAuthData method to return the id column on an upsert:
override def saveAuthData(authData: AuthData): Future[AuthData] =
db.run((auth returning auth.map(_.id)).insertOrUpdate(authData))
.map(idFromDb => authData.copy(id = idFromDb.getOrElse(authData.id)))
In the above code, idFromDb is a Some[Int] for an insert and a None for an update.
I'm trying to improve performance by replacing a dynamic field (a transient getter with no underlying database representation) with a derived field so that I can use, e.g., Criteria to query my model. The original dynamic field was pretty simple:
Client resolveClient() {
if (prevCall && prevCall.client) {
return prevCall.client
} else {
return client
}
}
I don't know how to reproduce that with a single MySQL statement, so I figured I would go ahead and stick it into a stored function, defined as follows:
CREATE FUNCTION `request_client`(requestId long) RETURNS varchar(255) CHARSET utf8
begin
declare pci long;
declare clientId long;
declare clientName varchar(255);
select request.prev_call_id
from request
where request.id = requestId
into pci;
if pci is not null then
select call_history.client_id
from call_history
where call_history.call_id = pci
into clientId;
else
select request.client_id
from request
where request.id = requestId
into clientId;
end if;
select clients.client_name
from clients
where clients.client_id = clientId
into clientName;
return clientName;
end;
And then I call that function in a derived field:
String derivedFieldName
static mapping = {
derivedFieldName formula: '(select stored_function(id))'
}
The problem is that now when I run any query on the domain, even as simple as Request.list(), I get the following exception:
Class: java.io.StreamCorruptedException
Message: invalid stream header: 32303135
For extra fun, this is an abstract domain class. I don't know if that really makes any difference; it's still persisted to the database like any other domain, and I'm calling the query on the abstract class itself, not an implementation.
The most frustrating thing is that the derived field itself does work! I can successfully retrieve a client name using it; I just can't query the overall domain.
Finally, I am pretty confident that the derived property is the issue, as I have commented it out and can then successfully query the domain.
If anybody comes across this later, the problem actually was the abstract class. And not just that it's an abstract class -- it's an abstract domain class. Apparently, Grails doesn't support derived properties on those.
To move querying to the database I just had to start saving the resolved client into my Request domain :/
I'm using EF5.0 in an ASP.NET MVC app. My Entity Model is named 'DataModel'. Included in the model is a table-valued function that exists in my MSSQL database, named MatchingEntries. It returns a table of integer ids.
I've looked at the DataModel.Context.cs file, that gets generated via the .tt (T4) template file. It has the following code in it:
[EdmFunction("DataEntities", "MatchingEntries")]
public virtual IQueryable<Nullable<int>> MatchingEntries(string term)
{
var termParameter = term != null ?
new ObjectParameter("Term", term) :
new ObjectParameter("Term", typeof(string));
return ((IObjectContextAdapter)this).ObjectContext.CreateQuery<Nullable<int>>("[DataEntities].[MatchingEntries](#Term)", termParameter);
}
The error I am getting results from using this method twice within the one query, such as:
IQueryable<int> one = db.MatchingEntries("\"one*\"");
IQueryable<int> two = db.MatchingEntries("\"two*\"");
List<int> both = one.Intersect(two).ToList();
The error is:
A parameter named 'Term' already exists in the parameter collection. Parameter names must be unique in the parameter collection.
Parameter name: parameter
Is this a known limitation of the classes generated from an EDMX for table-valued functions? With LINQ2SQL I am able to execute this a a single query to the database (that does a JOIN between the 2 outputs from MatchingEntries) and it replaces the parameter name #Term with #p0 and #p1 for the two different instances of the call. I'd like to make Entity Framework do the same.
So, my question is, how can I get EF to work in the same manner and avoid the 'Duplicate parameter' error?
My fallback is to evaluate each call to db.MatchingEntries separately, by putting ToList() after them. My other idea has been to replace the ObjectParameter name in the T4 generated Context.cs class with something randomly generated each time. These feel like hacks that I should be able to avoid.
This answer is Linq to Entities specific. This doesn't have to be done in Linq to SQL (Linqpad).
Thanks to this question I got a pointer to a viable solution:
extend the autogenerated DBContext class (partial class)
add a method with two parameters in the partial class
at calling, pass an index as second parameter
Detailed Answer:
DataEntitys.my.cs:
[EdmFunction("DataEntities", "MatchingEntries")]
public virtual IQueryable<Nullable<int>> MatchingEntries(string term, int index)
{
string param_name = String.Format("k_{0}", index);
var termParameter = term != null ?
new ObjectParameter(param_name, term) :
new ObjectParameter(param_name, typeof(string));
return ((IObjectContextAdapter)this).
ObjectContext.CreateQuery<Nullable<int>>(
String.Format("[DataEntities].[MatchingEntries](#{0})", param_name),
termParameter);
}
Call the function:
foreach (string teil in such)
{
index++;
if (teil.Trim() != "")
res = res.Join(db.MatchingEntries("\"" + teil + "*\"", index), l => l.ID, s => s.KEY, (l, s) => l);
}