I have a Tags table whose schema consists of only ID and Name (unique). Now, from the GUI user can enter tags for a BlogPost. When the data is saved, with tags stored in an array of string (names), I want to add tags whose names don't yet exist to the Tag table and ignore tags whose names already exist AND get back the list of all tag entities (including the existing and newly added ones). How can I do this in Entity Framework in just 1 SQL roundtrip?
For the returned tags, I want to associate them to the to-be-added BlogPost object (which is just instantiated and not stored in DB via EF yet). Is it still possible that this step can be combined with #1 in 1 single roundtrip or must I have to issue another query?
I don't believe the Entity Framework does batch inserts at all (at present). So if you must keep the number of DB roundtrips so low, you're probably going to have to use a stored procedure or a database trigger. Fortunately, the Entity Framework supports stored procedures which return entity types. There is documentation on MSDN about this. You could create a proc which accepts a string list of tags and returns tag entity instances. Alternately, you could add a VARCHAR column to your post table for a delimited list of tags, and parse it in the trigger.
Related
I'm using the Dynamics connector in Azure Data Factory.
TLDR
Does this connector support loading child records which need a parent record key passed in? For example if I want to create a contact and attach it to a parent account, I upsert a record with a null contactid, a valid parentcustomerid GUID and set parentcustomeridtype to 1 (or 2) but I get an error.
Long Story
I'm successfully connecting to Dynamics 365 and extracting data (for example, the lead table) into a SQL Server table
To test that I can transfer data the other way, I am simply loading the data back from the lead table into the lead entity in Dynamics.
I'm getting this error:
Failure happened on 'Sink' side. ErrorCode=DynamicsMissingTargetForMultiTargetLookupField,'Type=Microsoft.DataTransfer.Common.Shared.HybridDeliveryException,Message=,Source=,''Type=Microsoft.DataTransfer.Common.Shared.HybridDeliveryException,Message=Cannot find the target column for multi-target lookup field: 'ownerid'.
As a test I removed ownerid from the list of source columns it loads OK.
This is obviously a foreign key value.
It raises two questions for me:
Specifically with regards to the error message: If I knew which lookup it needed to use, how can I specify which lookup table it should validate against? There's no settings in the ADF connector to allow me to do this.
This is obviously a foreign key value. If I only had the name (or business key) for this row, how can I easily lookup the foreign key value?
How is this normally done through other API's, i.e. the web API?
Is there an XRMToolbox addin that would help clarify?
I've also read some posts that imply that you can send pre-connected data in an XML document so perhaps that would help also.
EDIT 1
I realised that the lead.ownertypeid field in my source dataset is NULL (that's what was exported). It's also NULL if I browse it in various Xrmtoolbox tools. I tried hard coding it to systemuser (which is what it actually is in the owner table against the actual owner record) but I still get the same error.
I also notice there's a record with the same PK value in systemuser table
So the same record is in two tables, but how do I tell the dynamics connector which one to use? and why does it even care?
EDIT 2
I was getting a similar message for msauto_testdrive for customerid.
I excluded all records with customerid=null, and got the same error.
EDIT 2
This link appears to indicate that I need to set customeridtype to 1 (Account) or 2 (Contact). I did so, but still got the same error.
Also I believe I have the same issue as this guy.
Maybe the ADF connector suffers from the same problem.
At the time of writing, #Arun Vinoth was 100% correct. However shortly afterwards there was a documentation update (in response to a GitHub I raised) that explained how to do it.
I'll document how I did it here.
To populate a contact with against a parent account, you need the parent accounts GUID. Then you prepare a dataset like this:
SELECT
-- a NULL contactid means this is a new record
CAST(NULL as uniqueidentifier) as contactid,
-- the GUID of the parent account
CAST('A7070AE2-D7A6-EA11-A812-000D3A79983B' as uniqueidentifier) parentcustomerid,
-- customer id is an account
'account' [parentcustomerid#EntityReference],
'Joe' as firstname,
'Bloggs' lastname,
Now you can apply the normal automapping approach in ADF.
Now you can select from this dataset and load into contact. You can apply the usual automapping approach, this is: create datasets without schemas. Perform a copy activity without mapping columns
This is the ADF limitation with respect to CDS polymorphic lookups like Customer and Owner. Upvote this ADF idea
Workaround is to use two temporary source lookup fields (owner team and user in case of owner, account and contact in case of customer) and with parallel branch in a MS Flow to solve this issue. Read more, also you can download the Flow sample to use.
First, create two temporary lookup fields on the entity that you wish to import Customer lookup data into it, to both the Account and Contact entities respectively
Within your ADF pipeline flow, you will then need to map the GUID values for your Account and Contact fields to the respective lookup fields created above. The simplest way of doing this is to have two separate columns within your source dataset – one containing Account GUID’s to map and the other, Contact.
Then, finally, you can put together a Microsoft Flow that then performs the appropriate mapping from the temporary fields to the Customer lookup field. First, define the trigger point for when your affected Entity record is created (in this case, Contact) and add on some parallel branches to check for values in either of these two temporary lookup fields
Then, if either of these conditions is hit, set up an Update record task to perform a single field update, as indicated below if the ADF Account Lookup field has data within it
I have three database views that are mapped in Hibernate as entities.
The entities are in a parent-child relationship (1 parent (A), 2 children(B & C)).
One of the children views (B) uses Oracle's dbms_utility.get_hash_value() to calculate its ID.
This is because it does a UNION over several tables that use different ID sequences and thus the IDs from there may not be unique.
I now have the very puzzling effect that a simple entityManager.find(B.class, id) cannot find the appropriate row.
When I look at the children through a loaded parent (A) entity, I can see that the ID shown in B is completely different from the one in the database. If I use this ID with entityManager.find(B.class, hibernateId), Hibernate finds the appropriate entity.
The database, on the other hand, only returns a value when using the ID shown in the ID column there (and not with the ID Hibernate shows).
Child entity C does not use the hash function and does not show this peculiar behaviour - which means the hash must be responsible.
Does anyone have an idea why?
We found the reason:
Child view B used all of its (content containing) columns as a string concatenation for the hash function.
This included date fields, which were not explicitly formatted when creating the string.
So, when Hibernate selected from the view, it obviously used another format than SQL Developer and thus produced completely different (but consistent) IDs.
Explicitly formatting the used date fields removed the problem.
As indicated in the Entity Framework image below, I have 3 tables, tblModel, tblModelFetish and tblFetish. A record in tblModel can have multiple records in the tblModelFetish table linked by the modelid column. The tblModelFetish table links to the tblFetish table via the fetishID column to get the fetish description stored in the fetish column. This Entity Model was generated with VS 2010 from an existing database including foreign keys.
a Entity Data Model http://spreadthenudes.com/efmodel.jpg
Using the odata syntax, I'm able to access all models (http://localhost:51157/WcfDataService.svc/tblModels) or a specific model (http://localhost:51157/WcfDataService.svc/tblModels(11)) successfully. I'm having trouble accessing the related tables data via odata, I've tried many permutations including expand etc.
What I want is a result set of all the columns in the tblModel and the related tblFetish records including the fetish column from the tblFetish table. In other words, Mary (a modelname in tableModel) has 3 fetishes (3 records in tblModelFetish) named beach, travel and coffee (stored in tblFetish, fetish column).
What is the odata syntax to acquire this?
thanks for reading! Bob
Try either:
http://localhost:51157/WcfDataService.svc/tblModels(11)?$expand=tblModelFetishes/tblFetish
or
http://localhost:51157/WcfDataService.svc/tblModels?$filter=id eq 11&$expand=tblModelFetishes/tblFetish
Just to make it clear you will not get one huge result set with all columns but the entity graph consisted of your entities.
I have created a web site using mvc 3 and Ef code first , now after publishing the site and it's DB I have found out that I need to add a new columns to one of my DB table,
(the DB already has a lot of data in it )
should I add the columns direct to the DB or should I add to the class?
(just a simple string with get and set)
And how can I do it without losing my data in the DB ?
thanks
Adding the columns to the class should be enough. Evidence you can find here.
Here is the full list of changes that migrations can take care of automatically:
Adding a property or class
Nullable columns will be assigned a value of null for any existing rows of data
Non-Nullable columns will be assigned the CLR default for the given data type for any existing rows of data
Renaming a property or class
See ‘Renaming Properties & Classes’ for the additional steps required here
Renaming an underlying column/table without renaming the property/class
(Using data annotations or the fluent API)
Migrations can automatically detect these renames without additional input
Removing a property
See ‘Automatic Migrations with Data Loss’ section for more information
I suggest you to add the columns direct to the DB and to the class, and test it on the local machine.
Entity framework returning only one value but the list size is correct
I have a table that does not have primary id and I need to get or select all the values in it.
What I see is when I do the selection with linq the number of objects is correct but it is the first row over and over.
I am simply doing something like this
List<MyValueType> valuesInDB = myDb.MyValueTypes.ToList();
Problem is I may get thousands of rows (which is correct) but the rows all have the same exact data.
I am using VS 2010 and used the wizard to create my EF object.
The problem is that entity framework is not able to work with entity without a key. So if your table doesn't specify a key, entity framework will infer its own. The key created by EF is composed of all non-nullable non-binary columns.
So if you for example have single non-nullable column in your entity which have only very small set of values (like enum) you will be able to load only single entity "per value". The reason is an inner implementation of the context and the state manager which uses Identity map pattern. When data record is retrieved from database, EF will first check an entity key and tries to find an object with the same key in its internal storage. If an object is found it will use that object instead of data record retrieved (despite of different data). If an object with the key is not found a new object is materialized and added to internal storage.
That is the purpose of Identity map - object with given key should be created only once by each context. Identity map is core pattern in ORM.
I wrote about Identity map also in this question.
I would suggest searching for the word "Warning" in your EDM's designer.cs file. It might tell you if Entity Framework is having any issues with your table.
I really can't comment much in the absence of the table design. I tried replicating your problem but wasn't able to do so. Here is what I did:
Created a table with no primary key but it had a unique key on an ID column. Entity Framework was able to infer a primary key and when I fetched the data, I not only got the correct number of rows but also the corrects data in those rows.
Created a table with no primary key and no unique key. Also there was no column called ID. Entity Framework excluded this table in the EDM that was generated. Consequently I wasn't able to query this table at all.This was displayed as a warning in the EDM designer file.
It would be better if you can share the create script for your table.