When I query the metadata using RetrieveMetadataChangesRequest, the RetrieveMetadataChangesResponse returns EntityMetadata and DeletedMetadata. The DeletedMetadata only returns the MetadataId.
Is there a way to get the metadata for the attribute without knowing the entity? Even just the attribute name would be fine.
RetrieveAttributeRequest I think only works if the attribute exists and if you have the entitylogicalname.
No, the only infomration available is the MetadataId.
Quoting from the SDK:
This collection is a dictionary of GUID values using a
DeletedMetadataFilters as a key. The GUID values represent MetadataId
values of the metadata items.
Looking at another part of the SDK specifically addresses this question:
You will also use DeletedMetadataFilters enumeration as a key to the
RetrieveMetadataChangesResponse.DeletedMetadata to filter the GUID
values found in the RetrieveMetadataChangesResponse.DeletedMetadata
property. When you design a metadata cache you will want to use the
MetadataId for each item so that you can identify deleted metadata
items and remove them.
So as a developer you are expected to populate a cache of metadata of interest to your application. You can query the CRM Metadata to find changes and deletes - but in the case of a delete you are responsible for having collected the metadata in your cache.
Related
I'm looking for a little "magic"
We have multiple applications written using entity framework. We need to update the scheme of a couple of columns - basically increasing the size of some account numbers columns. In our situation, we host the application for other customers and do not wish to increase the size of their account numbers but would like to have a single entity framework implementation for both.
The logic is the same with both tables - only the field length changes. This is a very large code base and refactoring, rewriting etc. the ideal solution.
Is there a way to specify in a config file what the field length is so it can be built at runtime?
Application
Table
Customer Name (256)
Account NUmber (10)
Same Application
Table
Customer Name (256)
Account Number (18)
You can write your own custom validation attribute with EF like in these examples: Custom validation attribute that compares the value of my property with another property's value in my model class
Pass variable data to ValidationAttribute
You can read your CustomerName property value, and based on the data you can validate your AccountNumber property. And in this custom validator you can read your config file.
I have an entity group in objectify, typical SomeParentClass and SomeChildClass. I want to do something like this to load an instance of SomeChildClass from the datastore.
ofy().load.type(SomeChildClass.class).id(idOfSomeChildClassInstace);
This is returning nothing found. Seems that you need to know the parent of SomeChildClass to get it from the datestore. This I know works.
Key<SomeChildClass> k = Key.create(someParentClass.generateKey(), SomeChildClass.class, idOfSomeChildClassInstace);
ofy().load().key(k).now;
What if I want to load an instance of SomeChildClass without knowing the parent, by just having the id of SomeChildClass.
You cannot do that - the actual full identifier of an entity is the kind and id of each of its ancestors as well as it's own kind and id. That is why building the full key works, but using just the child entity id does not. Another way of looking at it that ids are only unique between siblings of the same parent.
The easiest way to solve your issue is to produce a key for your child entity, then get the 'web safe string' for it. This string contains all the information of the entity and all it's parents and can be used to fully reconstitute the full id.
Using objectify:
String websafeKey = Key.create(parentKey, Entity.class, id).getString();
Key<Entity> key = Key.create(websafeKey);
You can also do this with the low level api if you need to.
You need to know the whole Key to be able to get() an entity. A child key consists of: kind, ID and parent key. So you need to provide all three.
Is it possible to define not-Long primary key?
Motivation: I have a set of XML files to convert to rdb. String attributes are used as unique keys.
Not possible.
From docs:
What should you do when you need to specify the id yourself?
Nothing. You shouldn’t do that. The id property is supposed to be generated and managed by db only. If you need to specify some external unique identifier, like, for instance, Amazon’s ASIN, just add an appropriate field to your entity and specify it as unique on SORM instantiation.
I've made a guestbook application using Google App Engine(GAE):python and the client is running on iPhone.
It has ability to write messages on the board with nickname.
The entity has 3 fileds:
nickname
date
message
And I'm about to make another feature that user can post reply(or comment) on a message.
But to do this, I think there should a 'primary key' to the guestbook entity, so I can put some information about the reply on a message.
With that three fields, I can't get just one message out of database.
I'm a newbie to database. Does database save some kind of index automatically? or is it has to be done by user?
And if it's done automatically by database itself(or not), how can I get just one entity with the key??
And I want to get some advise about how to make reply feature generally also. Thanks to read.
Every entity has a key. If you don't assign a key_name when you create the entity, part of the key is an automatically-assigned numeric ID. Properties other than long text fields are automatically indexed unless you specify otherwise.
To get an entity if you know the key, you simply do db.get(key). For the replies, you probably want to use a db.ReferenceProperty in the reply entity to point to the parent message; this will automatically create a backreference query in the message to get replies.
Each entity has a key, it contains information such as the kind of entity it is, it's namespace, parent entities, and the most importantly a unique identifier (optionally user specifiable).
You can get the key of an entity using the key method that all entities have.
message.key()
A key can be converted to and from a URL-safe string.
message_key = str(message.key())
message = Message.get(message_key)
If the key has a user-specified unique identifier (key name), you can access it like this
message.key().name()
Alternatively, if a key name was not specified, an id will be automatically assigned.
message.key().id()
To assign a key name to an entity, you must specify it when creating the entity, you are not able to add/remove or change the key name afterwards.
message = Message(key_name='someusefulstring', content='etc')
message.put()
You will then be able to fetch the message from the datastore using the key name
message = Message.get_by_key_name('someusefulstring')
Use the db.ReferenceProperty to store a reference to another entity (can be of any kind)
It's a good idea to use key name whenever possible, as fetching from the datastore is much faster using them, as it doesn't involve querying.
Example: I read data from an XML file. This data has unique id elements. I want to store those objects with their original unique id. How would I do that?
I figured out I could ask the managed object for it's ID, like this:
NSManagedObjectID *moID = [managedObject objectID];
but here the problem is: The XML tells me with the id element which object this is, and I need to look up in the database of core data if this object already exists in there, or not. So is it the only option to make an id attribute in my managed object model for that entity and then query for that? Then I will have two id systems right?
Don't worry about the ObjectID of Core Data. This is an internal unique ID which is not guarantied to be constant during the object's life cycle (e.g. it will change when you save the object to sql store). Just create a new mandatory attribute in your model and flag it as indexed so retrieval will be fast.
In the entity associated to this kind of objects, simply add another attribute of type string, call it objectID or similar and declare it to be mandatory.