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.
Related
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 reference material for CouchDB and Couchbase it's common guidance to store the type of a document as a parameter within the actual document.
I've got a database, where I have different documents that record certain behaviour by URL. So naturally, I use the URL as the id of the document.
The problem I find is that by using just the key as the document id, I now get clashes between documents of different types. So I have started using the type as the first part of the key like this:
{ doc._id: "rss_entry|http://www.spiegel.de/1234", [...] }
{ doc._id: "page_text|http://www.spiegel.de/1234", [...] }
Now I start to wonder why I've never seen this approach to model type in any of the documentation.
Prefixes are commonly used. In addition to support for scenarios such as yours, prefixing allows one to perform logical range queries against views. There is use of this technique in the modeling examples, but perhaps the concept is not described in as much detail as you are expecting. In the section http://docs.couchbase.com/couchbase-devguide-2.5/#modeling-documents, the documents are keyed as beer_NNNN and brewery_NNNN. Also, the section http://docs.couchbase.com/couchbase-devguide-2.5/#using-reference-documents-for-lookups goes a bit deeper into this technique. There is a counter document named user::count and then each user is keyed as user::NNNN. Additionally, there are documents in the example that are keyed as fb::NNNN for a Facebook ID, email::XXX#YYYY.com for a user's email address, etc.
According to the help pop up:
ID
This field's value represents the script ID, used to identify this
record for scripting purposes. It is a text field.
Internal ID
This field's value is a read-only system-generated unique identifier.
It is an integer field.
Both fields seem to uniquely identity a record type.
One is a string, one a integer.
The string ID is used for searches and
loading of records, but I've also seen Internal ID used when
referring to a record type from a lists point of view.
Can anyone provide the reasoning behind having two identifiers and when to use one versus the other when scripting?
The major difference is that you (as the creator of a custom record or script) are in complete control of the text ID. You can establish patterns and best practices for defining these IDs, and it will make it very easy for developers to identify record types just by looking at the string ID. You have no control over the numeric ID. When looking at code, it is much easier for me to determine what records I am referring to if it looks like:
nlapiSearchRecord('customrecord_product', null, filters, columns);
nlapiResolveURL('SUITELET', 'customscript_sl_orderservice', 'customdeploy_sl_orderservice')
as opposed to looking at:
nlapiSearchRecord(118, null, filters, columns);
nlapiResolveURL('SUITELET', 13, 1)
I'm not even sure the second nlapiSearchRecord actually works, but I know that nlapiResolveURL can be written that way.
That said, if you simply let NetSuite generate the text ID, you'll end up with generic IDs like customrecord1, which I find no more useful than the numeric ID. It is a good practice to explicitly specify your own IDs.
Furthermore, the numeric ID can vary between environments (e.g. Sandbox could be different than Production, until a subsequent refresh occurs). If you are following good migration practices, then the text ID should never vary between environments, so your code would not have to make any kind of decision on which ID to use based on environment.
Rarely have I found myself referencing any record, whether native or custom, by its numeric ID; scripts are always using the text ID to reference a record type.
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 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.