I have a stored procedure that is run and returns a result set into a model (using EF 5).
As I'm looping through the result set, I simply want to get the name of the column in the model that is used to hold the data.
How can I achieve this?
Would it be something like below:
var myCustomers = DbContext.Database.SqlQuery<Customer>
("exec SelectCustomers").ToList();
foreach (Customer cust in myCustomers)
{
}
Displaying the value "myCustomers[0].Address1" during runtime will display the actual value inside that field, but how can I simply extract the column name?
If I try something like below, the index value is always -1 and I don't know what I'm missing. I've used it dozens of times.
int Idx = myCustomers[0].Address1.IndexOf(".").ToString();
"-1"
I don't think you can reliably do that. EF consists of 3 layers - object layer (also called O-Space - your types), conceptual layer (also called C-Space - a model in EDM terms) and store layer (also called S-Space which described the database). The mapping between O-Space and S-Space is more or less 1:1 - so a property on a class maps to an entity property in the OSpace model. However there are a few strategies of mapping C-Space to S-Space like Table Per Hierarchy (TPH), Table per Type (TPT), Table per Concrete type (TPC) and Entity Splitting (you can find more details here: http://blogs.msdn.com/b/adonet/archive/2010/10/25/inheritance-mapping-a-walkthrough-guide-for-beginners.aspx). It is also possible to use your own name for a property that will be different from the name of a corresponding column in the database. In the simplest cases property names will match column names but oftentimes it won't be the case. At runtime the information about mapping is stored types that are mostly internal and you cannot access them. The information about mapping is populated from the Msl artifact the describes mapping between C- and S- space. You could try parsing this artifact (it's an Xml file) but it's not an easy task if you need to support all different mapping strategies.
Related
I have stored my column as a JSON object in my DynamoDB table.
receiver:[{id: 'r1', name: 'a'},{id: 'r2', name: 'b'},{id: 'r3', name: 'c'},]
I want to get the item if r1 is a receiver.
I tried using the FilterExpression receiver[0].id = 'r1' and it did return the item. However, what if the index of r1 was not at 0? How would i be able to map through the object?
DynamoDB is not great for search, especially within complex attribute types like lists or maps. While useful, these complex attribute types are not well suited for search.
One place where they can be useful is if you have known keys. For example, imaging an attribute named phone_numbers that stores home, work and cell phone numbers:
phone_numbers:{
home: "(555) 123-4567"},
work: "(555) 246-8910"},
cell: "(123) 345-1231"}
}
Storing your data in this way allows you to fetch a users home/work/cell phone number. However, it does not support searching for phone numbers by area code.
If you need to search the data stored in your complex attribute, you'll need to get the data in a more useful format (e.g. in it's own attribute). Better yet, incorporate it into your primary key!
I have two classes (say Database and Record). In Database class, I have a method named getRecords() that returns a list of Record objects.
In Java, the above method can be written as:
List<Record> getRecords(){..}
In StarUML, while designing Class diagram, I tried giving
+getRecords() : Record[0..*]
But StarUML refused to create method like above. When I tried with the one below, it works
+getRecords() : ArrayList<Record>
But this is more specific to Java. I want to implement something like Record[0..*] in StarUML. Is it possible to write methods in such format or the Java style of return type is the only solution ?
I don't know why StarUML refuses to parse the text, but you can still create it via model.
Add the operation and call it getRecords()
Right-click on the operation (in diagram or model), and select Add > Parameter
Select parameter in Model Explorer (probably the parameter is already selected when you created it) and set the direction parameter to return. This is how UML represents return types.
(Configure the type, multiplicity, and anything else you need.)
Note that the default collection in UML is Set, so you should check isOrdered, as List is an ordered collection.
I am facing an issue with extended attributes on a document (trying to extend a document table). I created the original table’s PK (FDOC_NBR) in the extended table and linked the two via a foreignKey of the customized original table’s ojb entry (as an “extension” reference-descriptor). I created the bo and dd for the extension and customized the original document’s dd to add the new attributes. On the extended BO itself I also added members (with setters and getters) for the 2 new columns + for the PK column of documentNumber. I also added the new attributes to the documet’s jsp. The pertinent module definition was already extended to include custom dd, ojb, etc. files.
Indeed, when opening the document the new fields are shown- however, when trying to submit the document (regardless of doing anything with the new fields) I get an error-
Error Details: OJB operation; SQL []; ORA-01400: cannot insert NULL
into ("KFSTEM"."TEM_TRVL_ARRANGER_DOC_EXT_T"."FDOC_NBR") ; nested
exception is java.sql.SQLIntegrityConstraintViolationException:
ORA-01400: cannot insert NULL into
("KFSTEM"."TEM_TRVL_ARRANGER_DOC_EXT_T"."FDOC_NBR")
Seems like somehow the system tries to insert a value of NULL into the extension’s PK field, instead of the actual document number. Trying to debug this, in the action’s route method and all the way down to DocumentDaoOjb.save (which is as far down as I can go) I see the document with the real doc number is passed on, so the problem seems to be purely with ojb trying to set this number to the extension table.
Does anyone have any experience with extended attributes on documents that could help shed some light on this?
KFS is using the KNS, and in the Kuali Nervous System, the primary key on the extended attributes object must be set through manual intervention.
In this case, it looks as if you're adding an extended attribute to a transactional document, the Travel Arranger document (TAA), which simplifies things. Basically, you'll need to extend org.kuali.kfs.module.tem.document.TravelArrangerDocument and override prepareForSave to set the document number there (it may be set already since prepareForSave should be called several times during the routing process, but there's no real harm from overwriting that information as the base document's number will remain the same).
Hope this helps!
In a JSF page I have to display the data from an entity.
This entity has some int fields which cannot be displayed directly but need to be translated into a descriptive string.
Between them some can have a limited number of values, others have lots of possible values (such as a wordlwide Country_ID) and deserve a table on the Db with the association (ID, description).
This latter case can easily be solved navigating via relationship from the original entity to the entity corresponding to the dictionary table (ID, description) but I don't want to introduce new entities just to solve translations form ID to description.
Besides another integer field has special needs: the hundred thousand number should be changed with a letter according to a rule such as 100015 -> A00015, 301023 -> C01023.
Initially I put the translation code inside the entity itself but I know the great limits and drawbacks of this solution.
Then I created a singletone (EntityTranslator) with all the methods to translate the different fields. For cases where the field values are a lot I put them inside a table which is loaded from the singletone and transformed in a TreeMap, otherwise the descriptions are in arrays inside the class.
In the ManagedBean I wrote a getter for EntityTranslator and inside the jsf I use quite long el statements like the following:
#{myManagedBean.entityTranslator.translateCountryID(myManagedBean.selectedEntity.countryID)}
I think the problem is quite general and I'm looking for a standard way to solve it but, as already stated, I don't want to create new 'stupid' entities only to associate an ID to a description, I think it is overkill.
Another possibility is the use of converters Object(Integer) <-> String but I'm more comfortable in having all the translation needs for an Entity inside the same class.
Your question boils down to the following simple line:
How can I display a field different from id of my entity in my view and how can I morph an integer field into something more meaningful.
The answer is that it depends on a situation.
If you solely want to input/output data, you don't need id at all apart from the possible view parameter like ?id=12345. In this case you can input/output anything you want in your view: the id is always there.
If you want to create a new entity most possibly you have a way of generating ids via JPA, or database, or elsehow besides the direct input from the user. In this situation you don't need to mess with ids as well.
If you want to use information on other entities like show user a dropdown box with e.g. a list of countries, you always have the option to separate label (let it be name) and value (let it be id), or even have a unique not null column containing the country name in your database table that will serve as a natural identifier. If you'd like to get data from the user using an input text field you always can create a converter that will do the job of transforming user input strings to actual entity objects.
Regarding the transformation of your integers, you've actually got several choices: the first one is to attach a converter for these fields that will roughly do 301023 -> C01023 and C01023 -> 301023 transformations, the second one is to write a custom EL function and the third one is to prepare the right model beforehand / do the transformations on-the-fly.
I need to work with an existing (MySql) db, where the names of tables and columns are already defined.
If I understand the documentation properly (and I didn't find good documentation on this subject, so links will be highly appreciated), table names are related to PersistIdentity, and must therefore begin with a capital letter (which is not the case I'm facing).
Column names, however, are automatically un-capitalized (at least that's what is implied in the Yesod book, Persistent chapter, in the code snippet describing the code automatically generated from declarations), so columns in the DB must begin with a lowercase letter.
Is the description above indeed true?
Can I control specifically the mapping of tables to identities and columns to fields?
If not then what are the rules automatically applied for the naming? What names are therefore forbidden?
Also, one of the fields is a VARCHAR(30). How can I communicate that to Persistent? It currently complains (through yesod devel) that:
errMessage = "BLOB/TEXT column 'my_field' used in key specification without a key length"}
Which is the result of auto-migration (which I probably should disable anyway). However, if I do want to declare a bounded VARCHAR field - can I do that through Persistent and its auto-migration tool?
Thanks,
I'm not an authority on the MySQL backend, but IIRC (and based on the code), you can control the maximum length by using the maxlen=... attribute. Similarly, you can have direct control of the name the field will have in the database by using the sql=... attribute. So, for example, the following might work:
Person sql=people
name Text sql=full_name maxlen=40
age Int
I also agree that you should disable the automigration code if you're dealing with a pre-existing schema.