Still on the task of reading class elements from SQL using JDBC... And I have a problem with class parameters.
Given those two SQL queries (both in namespace SAMPLES):
select name, sequenceNumber from %Dictionary.PropertyDefinition
where parent = 'Sample.Person';
select name, sequenceNumber
from %Dictionary.ParameterDefinition
where parent = 'Aviation.Cubes.Aircraft.StarAircraftModel';
the first query will correctly report the sequence number in the source file as it has been written.
However, this is not the case for the second query: sequenceNumber is always 0!
How do I obtain the "position" of a parameter?
Second query correct as well, but wrong target, because, such behavior possible for generated classes. You can see it by non-empty GeneratedBy property in definition for this class. If you try to do it for Sample.Person it will shown correctly.
But I still don't understand why you use JDBC, because it's so slow. I am not sure what are you doing, but maybe, my code can help you. Java class for reading Cache classes.
Related
I am trying to create a custom template fragment that builds a table of value properties. I started by creating a SQL query fragment that pulls all properties classified by a Value Type. Now I would like to pull in the default (initial) value assigned. I figured out that it's in the Description table of t_xref, with the property guid in the client field, but I don't know how to write a query that will reliably parse the default value out since the string length may be different depending on other values set. I tried using the template content selector first but I couldn't figure out how to filter to only value properties. I'm still using the default .qeax file but will be migrating to a windows based DBMS soon. Appreciate any help!
Tried using the content selector. Successfully built a query to get value properties but got stuck trying to join and query t_xref for default value.
Edited to add current query and image
Value Properties are block properties that are typed to Value Types. I'm using SysML.
This is my current query, I am no SQL expert! I don't pull anything from t_xref yet but am pulling out only the value properties with this query:
SELECT property.ea_guid AS CLASSGUID, property.Object_Type AS CLASSTYPE, property.Name, property.Note as [Notes], classifier.Name AS TYPE
FROM t_object property
LEFT JOIN t_object classifier ON property.PDATA1 = classifier.ea_guid
LEFT JOIN t_object block on property.ParentID = block.Object_ID
WHERE block.Object_ID = #OBJECTID# AND property.Object_Type = 'Part' AND classifier.Object_Type = 'DataType'
ORDER BY property.Name
I guess that Geert will come up with a more elaborate answer, but (assuming you are after the Run State) here are some details. The value for these Run States is stored in t_object.runstate as one of the crude Sparxian formats. You find something like
#VAR;Variable=v1;Value=4711;Op==;#ENDVAR;
where v1 is the name and 4711 the default in this example. How you can marry that with your template? Not the faintest idea :-/
I can't give a full answer to the original question as I can't reproduce your data, but I can provide an answer for the generic problem of "how to extract data through SQL from the name-value pair in t_xref".
Note, this is heavily dependent on the database used. The example below extracts fully qualified stereotype names from t_xref in SQL Server for custom profiles.
select
substring(
t_xref.Description, charindex('FQName=',t_xref.Description)+7,
charindex(';ENDSTEREO',t_xref.Description,charindex('FQName=',t_xref.Description))
-charindex('FQName=',t_xref.Description)-7
),
Description from t_xref where t_xref.Description like '%FQName%'
This works using:
substring(string, start, length)
The string is the xref description column, and the start and length are set using:
charindex(substring, string, [start position])
This finds the start and end tags within the xref description field, for the data you're trying to parse.
For your data, I imagine something like the below is the equivalent (I haven't tested this). It's then a case of combining it with the query you've already got.
select
substring(
t_xref.Description, #the string to search in
charindex('#VALU=',t_xref.Description,charindex('#NAME=default',t_xref.Description)+6, #the start position, find the position of the first #VALU= tag after name=default
charindex('#ENDVALU;',t_xref.Description,charindex('#VALU=',t_xref.Description))
-charindex('#VALU=',t_xref.Description,charindex('#NAME=default',t_xref.Description))-6 #the length, find the position of the first #ENDVALU tag after the start, and subtract it from the start position
),
Description from t_xref where t_xref.Description like '%#NAME=default%' #filter anything which doesn't contain this tag to avoid "out of range" index errors
Im currently using jOOQ to build my SQL (with code generation via the mvn plugin).
Executing the created query is not done by jOOQ though (Using vert.X SqlClient for that).
Lets say I want to select all columns of two tables which share some identical column names. E.g. UserAccount(id,name,...) and Product(id,name,...). When executing the following code
val userTable = USER_ACCOUNT.`as`("u")
val productTable = PRODUCT.`as`("p")
create().select().from(userTable).join(productTable).on(userTable.ID.eq(productTable.AUTHOR_ID))
the build method query.getSQL(ParamType.NAMED) returns me a query like
SELECT "u"."id", "u"."name", ..., "p"."id", "p"."name", ... FROM ...
The problem here is, the resultset will contain the column id and name twice without the prefix "u." or "p.", so I can't map/parse it correctly.
Is there a way how I can say to jOOQ to alias these columns like the following without any further manual efforts ?
SELECT "u"."id" AS "u.id", "u"."name" AS "u.name", ..., "p"."id" AS "p.id", "p"."name" AS "p.name" ...
Im using the holy Postgres Database :)
EDIT: Current approach would be sth like
val productFields = productTable.fields().map { it.`as`(name("p.${it.name}")) }
val userFields = userTable.fields().map { it.`as`(name("p.${it.name}")) }
create().select(productFields,userFields,...)...
This feels really hacky though
How to correctly dereference tables from records
You should always use the column references that you passed to the query to dereference values from records in your result. If you didn't pass column references explicitly, then the ones from your generated table via Table.fields() are used.
In your code, that would correspond to:
userTable.NAME
productTable.NAME
So, in a resulting record, do this:
val rec = ...
rec[userTable.NAME]
rec[productTable.NAME]
Using Record.into(Table)
Since you seem to be projecting all the columns (do you really need all of them?) to the generated POJO classes, you can still do this intermediary step if you want:
val rec = ...
val userAccount: UserAccount = rec.into(userTable).into(UserAccount::class.java)
val product: Product = rec.into(productTable).into(Product::class.java)
Because the generated table has all the necessary meta data, it can decide which columns belong to it, and which ones don't. The POJO doesn't have this meta information, which is why it can't disambiguate the duplicate column names.
Using nested records
You can always use nested records directly in SQL as well in order to produce one of these 2 types:
Record2<Record[N], Record[N]> (e.g. using DSL.row(table.fields()))
Record2<UserAccountRecord, ProductRecord> (e.g using DSL.row(table.fields()).mapping(...), or starting from jOOQ 3.17 directly using a Table<R> as a SelectField<R>)
The second jOOQ 3.17 solution would look like this:
// Using an implicit join here, for convenience
create().select(productTable.userAccount(), productTable)
.from(productTable)
.fetch();
The above is using implicit joins, for additional convenience
Auto aliasing all columns
There are a ton of flavours that users could like to have when "auto-aliasing" columns in SQL. Any solution offered by jOOQ would be no better than the one you've already found, so if you still want to auto-alias all columns, then just do what you did.
But usually, the desire to auto-alias is a derived feature request from a misunderstanding of what's the best approch to do something in jOOQ (see above options), so ideally, you don't follow down the auto-aliasing road.
Is there some scala relational database framework (anorm, squeryl, etc...) using postgres-like aggregators to produce lists after a group-by, or at least simulating its use?
I would expect two levels of implementation:
a "standard" one, where at least any SQL grouping with array_agg is translated to a List of the type which is being aggregated,
and a "scala ORM powered" one where some type of join is allowed so that if the aggregation is a foreign key to other table, a List of elements of the other table is produced. Of course this last thing is beyond the reach of SQL, but if I am using a more powerful language, I do not mind some steroids.
I find specially intriguing that the documentation of slick, which is based precisely in allowing scala group-by notation, seems to negate explicitly the output of lists as a result of the group-by.
EDIT: use case
You have the typical many-to-many table of, say, products and suppliers, pairs (p_id, s_id). You want to produce a list of suppliers for each product. So the postgresql query should be
SELECT p_id, array_agg(s_id) from t1 group by p_id
One could expect some idiomatic way to to this in slick, but I do not see how. Furthermore, if we go to some ORM, then we could also consider the join with the tables products and suppliers, on p_id and s_id respectively, and get as answer a zip (product, (supplier1, supplier2, supplierN)) containing the objects and not only the ids
I am also not sure if I understand you question correct, could you elaborate?
In slick you currently can not use postgres "array_agg" or "string_agg" as a method on type Query. If you want to use this specific function then you need to use custom sql. But: I added an issue some time ago (https://github.com/slick/slick/issues/923, you should follow this discussion) and we have a prototype from cvogt ready for this.
I needed to use "string_agg" in the past and added a patch for it (see https://github.com/mobiworx/slick/commit/486c39a7ed90c9ccac356dfdb0e5dc5c24e32d63), so maybe this is helpful to you. Look at "AggregateTest" to learn more about it.
Another possibility is to encapsulate the usage of "array_agg" in a database view and just use this view with slick. This way you do not need "array_agg" directly in slick.
You can use slick-pg.
It supports array_agg and other aggregate functions.
Your question is intriguing, care to elaborate a little on how it might ideally look? When you group by you often have an additional column, such as count(*) over and above the standard columns from your case class, so what would the type of your List be?
Most of my (anorm) methods either return a singleton (perhaps Option) or a List of that class's type. For each case class, I have an sqlFields variable (e.g. m.id, m.name, m.forManufacturer) and a single parser variable that I reference as either .as(modelParser.singleOpt) or .as(modelParser *). For foreign keys, a lazy val at the case class level (or def if it needs to be) is pretty useful. E.g. if I had Model and Manufacturer entities, with a foreign key forManufacturer on Model, then I might define a lazy val manufacturer : Manufacturer = ... in the case class of the model, so that at any time I can refer to model.manufacturer. I can define joins as their own methods, either in this way, or as methods in the companion object.
Not 100% sure I am answering your question, but thought this was a bit long for a comment.
Edit: If your driver supported parsing of postgresql arrays, you could map them directly to a class like ProductSuppliers(id:Int, suppliers:List[Int]) (or even List[Supplier]?) In anorm that's about as idiomatic as one could get, I think? For databases that don't support it, it seems to me similar to an order by version, i.e. select p1, s1 from t1 order by p1, which you could groupBy p1 and similarly map to ProductSuppliers.
I want to do something like this in OrmLite
SELECT *, COUNT(title) as titleCount from table1 group by title;
Is there any way to do this via QueryBuilder without the need for queryRaw?
The documentation states that the use of COUNT() and the like necessitates the use of selectRaw(). I hoped for a way around this - not having to write my SQL as strings is the main reason I chose to use ORMLite.
http://ormlite.com/docs/query-builder
selectRaw(String... columns):
Add raw columns or aggregate functions
(COUNT, MAX, ...) to the query. This will turn the query into
something only suitable for using as a raw query. This can be called
multiple times to add more columns to select. See section Issuing Raw
Queries.
Further information on the use of selectRaw() as I was attempting much the same thing:
Documentation states that if you use selectRaw() it will "turn the query into" one that is supposed to be called by queryRaw().
What it does not explain is that normally while multiple calls to selectColumns() or selectRaw() are valid (if you exclusively use one or the other),
use of selectRaw() after selectColumns() has a 'hidden' side-effect of wiping out any selectColumns() you called previously.
I believe that the ORMLite documentation for selectRaw() would be improved by a note that its use is not intended to be mixed with selectColumns().
QueryBuilder<EmailMessage, String> qb = emailDao.queryBuilder();
qb.selectColumns("emailAddress"); // This column is not selected due to later use of selectRaw()!
qb.selectRaw("COUNT (emailAddress)");
ORMLite examples are not as plentiful as I'd like, so here is a complete example of something that works:
QueryBuilder<EmailMessage, String> qb = emailDao.queryBuilder();
qb.selectRaw("emailAddress"); // This can also be done with a single call to selectRaw()
qb.selectRaw("COUNT (emailAddress)");
qb.groupBy("emailAddress");
GenericRawResults<String[]> rawResults = qb.queryRaw(); // Returns results with two columns
Is there any way to do this via QueryBuilder without the need for queryRaw(...)?
The short answer is no because ORMLite wouldn't know what to do with the extra count value. If you had a Table1 entity with a DAO definition, what field would the COUNT(title) go into? Raw queries give you the power to select various fields but then you need to process the results.
With the code right now (v5.1), you can define a custom RawRowMapper and then use the dao.getRawRowMapper() method to process the results for Table1 and tack on the titleCount field by hand.
I've got an idea how to accomplish this in a better way in ORMLite. I'll look into it.
In an XmlData column in SQL Server 2008 that has no schema assigned to it, how can I pull the first item at a particular node level? For example, I have:
SELECT
XmlData.value('//*/*[1]','NVARCHAR(6)')
FROM table
where XmlData.Exist('//*/*[1]') = 1
I assume this does not work because if there are multiple nodes with different names at the 2nd level, the first of each of those could be returned (and the value() requires that a singleton be selected.
Since I don't know what the names of any nodes will be, is there a way to always select whatever the first node is at the 2nd level?
I found the answer by chaining Xquery .query() and .value()
XMLDATA.query('//*/*[1]').value('.[1]','NVARCHAR(6)')
This returns the value of the first node and works perfectly for my needs.