Re: Preferred way for fetching with given SQL select statement?
Re: Preferred way for fetching with given SQL select statement?
- Subject: Re: Preferred way for fetching with given SQL select statement?
- From: Chuck Hill <email@hidden>
- Date: Thu, 24 Sep 2015 22:48:34 +0000
- Thread-topic: Preferred way for fetching with given SQL select statement?
The challenge is going to be "In addition these statements are
parameterized with ? so they can be precompiled and then used with
different query values²
You might be able to parse and rewrite those as EOQualifierVariables and
then use qualifier.qualiferWithBindings, but you are going to have to know
the bindings for each statement. That all might be as much work as making
proper EOQualifiers.
Chuck
On 2015-09-24, 11:48 AM,
"webobjects-dev-bounces+chill=email@hidden on behalf of
Johann Werner" <webobjects-dev-bounces+chill=email@hidden
on behalf of email@hidden> wrote:
>Hi Markus,
>
>I did not clearly understand what you are exactly trying to achieve. If
>you just need to run the vendor specific SQL to get a list of primary
>keys that you can then use to fetch the EOs you want you could do
>something like
>
>
>EOEditingContext ec = ERXEC.newEditingContext();
>EOEntity entity = ERXEOAccessUtilities.entityNamed(MyEntity.ENTITY_NAME);
>EODatabaseContext context =
>EODatabaseContext.registeredDatabaseContextForModel(entity.model(), ec);
>EOSQLExpressionFactory factory =
>context.database().adaptor().expressionFactory();
>EOSQLExpression expression = factory.expressionForString("SELECT Š");
>NSArray<NSDictionary> rawRows =
>ERXEOAccessUtilities.rawRowsForSQLExpression(ec, entity.model().name(),
>expression);
>NSArray<Integer> idList = rawRows.valueForKey("id³);
>NSArray<MyEntity> result = MyEntity.fetchMyEntities(ec, ERXQ.in("id",
>idList), null);
>
>
>Otherwise if you need more than that and need to fetch EOs but have to
>use your own SQL instead of the generated one by EOF you probably can do
>this by using the hints dictionary of a fetch specification. Something
>like
>
>
>EOEditingContext ec = ERXEC.newEditingContext();
>ERXFetchSpecification<MyEntity> fs = new
>ERXFetchSpecification<>(MyEntity.ENTITY_NAME);
>NSDictionary<String, String> hints = new NSDictionary<>("SELECT Š" ,
>EODatabaseContext.CustomQueryExpressionHintKey);
>fs.setHints(hints);
>NSArray<MyEntity> result = fs.fetchObjects(ec);
>
>
>Though I never used that sort of logic but you could experiment with
>that. All code above is written by peeking at the API documentation with
>extremely wild guesses included‹so no guarantees that it is correct or
>complete. Use at your own risk ;-)
>
>jw
>
>
>> Am 24.09.2015 um 16:22 schrieb Markus Ruggiero
>><email@hidden>:
>>
>> Folks,
>>
>> What is the preferred way to fetch EOs when you have a db vendor
>>specific "select id from ... where ....." statement?
>>
>> I need to interface with a legacy system where I have to incorporate
>>the functionality of an external java tool into a Wonder app. This
>>external tool executes raw SQL select statements which it reads from a
>>file. All the statements are in the form given above and return a list
>>of primary key values (single column fortunately). The tool then
>>iterates through that list and does whatever it has to do (issuing tons
>>of more raw sql). My problem is that these select statements are rather
>>complex and there are many of them. It is just not feasible to replace
>>those with proper EOQualifiers. In addition these statements are
>>parameterized with ? so they can be precompiled and then used with
>>different query values. However everything can be done with standard EOs
>>as soon as I have those corresponding to the returned list of ids.
>>
>> Thanks a lot
>> ---markus‹
>
>
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