Yes, it does help, what I was missing is that if I need to have code that
works with TWO dialect at the same time, I need `Require` to force my code
to be compatible with both. `Allow` wouldn't help with this.
Following this, I'm wondering what would be the use case for `Allow` then:
is there some case when it makes sense to allow two different dialects?
You wouldn't want to mix in a same query two dialects, and if it's in
different queries, then you juste need to apply two different `Require`
annotation on different scope.
Does this make sense?
Le vendredi 30 août 2019 16:51:30 UTC+2, Lukas Eder a écrit :
>
> Hi Victor,
>
> Put shortly, Allow is a disjunction (OR) whereas Require is a conjunction
> (AND)
>
> - @Allow({ ORACLE, POSTGRES }) means that you allow for both of these
> dialects to be used in general. No other dialect may be used (e.g. MYSQL).
> If an API supports only one of the two dialects, e.g. CONNECT BY
> (supported
> by Oracle), then it is still allowed.
> - @Require({ ORACLE, POSTGRES }) will now require *both* Oracle and
> PostgreSQL support on any API. In this case, CONNECT BY will no longer
> work, because it is not supported by PostgreSQL
>
> In your case, you could just use @Allow(POSTGRES) only. You don't have to
> Allow(DEFAULT), I don't think this adds much value. If you're only working
> with a single RDBMS, you don't need @Require. But you could add it, and
> then add a second dialect in the future, should you choose to support
> another RDBMS.
>
> Perhaps, code explains this better? Here's the implementation from
> Tools.checkSQLDialect():
>
>
> boolean allowedFail = true;
> allowedLoop:
> for (SQLDialect a : allowed) {
> for (SQLDialect s : supported) {
> if (a.supports(s)) {
> allowedFail = false;
> break allowedLoop;
> }
> }
> }
>
> if (allowedFail)
> return error.apply("The allowed dialects in scope " + allowed + " do
> not include any of the supported dialects: " + supported);
>
> boolean requiredFail = false;
> requiredLoop:
> for (SQLDialect r : required) {
> for (SQLDialect s : supported)
> if (r.supports(s))
> continue requiredLoop;
>
> requiredFail = true;
> break requiredLoop;
> }
>
> if (requiredFail)
> return error.apply("Not all of the required dialects " + required + "
> from the current scope are supported " + supported);
>
>
>
> I hope this helps.
> Lukas
>
> On Fri, Aug 30, 2019 at 3:35 PM Victor Noël <victo...@gmail.com
> <javascript:>> wrote:
>
>> Hi,
>>
>> I think I'm a bit thick with this, but I just can't wrap my head around
>> the difference (and more importantly the need) for both Allow and Require
>> annotations with jooq-checker.
>>
>> Maybe it's because my use case does not need both, so let me explain what
>> it is:
>> - I have some code (maybe used by different applications, so it's kind of
>> library code) that do db related stuffs, and if it is possible, I want this
>> code as generic as possible w.r.t. the database dialect
>> - because I mostly use postgresql, sometimes I use postgresql-specific
>> features (still in library code)
>> - in some specific cases, I DO know which database I am using
>> (disclaimer: it's postgresql :P) for my application (so it's not library
>> code)
>>
>> What I did is annotate most of this code with `Allow(SQLDialect.DEFAULT)`
>> and when it wasn't enough, I used `Allow(SQLDIALECT.POSTGRES)`.
>>
>> Some questions:
>> - I'm not sure it is correct to use the DEFAULT dialect for this, but I
>> suppose it is?
>> - I don't see the need for Require here, is it only needed when I am
>> working with multiple dialects (not DEFAULT) at the same?
>> - Is Allow some kind of architecture-level rule while Require some kind
>> of class-level assertion?
>>
>> Thanks for any help to understand this :)
>>
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