Does anybody know what the symbols mean that are next to the properties in the Entity Framework:
The first one next to TypeID is an indication of a key column. The second one is a symbol for regular property.
Related
I'm new to both Visual Paradigm and ERD. I created an entity, but am a bit lost what some of the notation is. I'm not sure what the large 'N' is, or the number 10 associated with the ID integer (both were autogenerated when creating a column). Any help would be great, I can't seem to find this in the documentation.
The "N" indicate the column is nullable or not.
The column type (integer or number) is subject to the target database specified for your project (under Tools > DB > Database Configuration). For example, by specify project target DB as Oracle then the columns with integer(10) will automatically change to number(10).
You can mark a column as primary key by simply adding "+" sign in front of the column name while in-line editing the column in ERD.
You can find the general ERD modeling tips for Visual Paradigm at https://www.visual-paradigm.com/support/documents/vpuserguide/3563/3564/85375_drawingentit.html
Wit.ai provides an entity of type "trait". Wit.ai defines trait entities as
When the entity value is not inferred from a keyword or specific
phrase in the sentence. There is no obvious association between
certain words in the sentence and the value of the entity, but rather
you need the sentence as a whole to determine the value.
(https://wit.ai/docs/recipes#which-entity-should-i-use)
I'm curious to know how does this work? For example,
I want to know the status
Check the status
How is it going?
I want to extract the entity entities["cmd":"status"] from all of these statements. How do I go on about starting to implement this?
When writing a where condition on an Entity Framework context object, is there a shorthand way of testing all the columns, sort of like this:
context.tableName.where(t => t.AnyColumn.Contains(...))
Or am I forced to test each column individually?
There is no out-of-the-box way to do that but you can write your own method which will use reflection to get the list of your model's properties and check each of them
I don't know that this is possible you may have to search each field individually, but why not search for a value in a specific column instead of searching the whole table, it reduces the room for error and makes for a quicker query
I have a Parent Entity Person. It has two Child Entities, Man and Woman.
I want to do a NSFetchedResultsController with them sectioned by the Entity (secion 0 would be Men, section 1 would be Women).
Can I sort them by section based on which Class it is (Man Class vs Women Class? Or do I need to add an attribute stating if its Man or Woman and section by that?
self.entity.name will return the entity name as an NSString. So you could use that. I don't think it's such a great idea to have internal details (the name of an Entity) drive the UI. It's easy enough to declare an attribute for the section name, and then you have full control of the name (including localization).
I'm using Entity Framework 4 and with a Database First binding, and EF is not generating the entities for a few of my tables. I'm not getting any errors, and no matter how many times I select the tables to generate from the "Update Model from Database" popup menu on the design surface, the same tables are still missing from the model.
I get no errors in the wizard. They just don't get generated. Any clues?
EF requires a primary key on the table. EF will not map tables for which it can't find or derive a primary key. If all columns are nullable, it can't assume a primary key. If one or more columns are not nullable, EF will evidently derive a primary key for the table.
EF will ignore table without primary keys.
Options I can think of:
Did you check the box next to those tables?
Did you previously add them, then delete their entities but keep the cache of the tables?
If so you can remove them from entity browser window and re-add them
or manually add entities and define the table they map to in mappings window.
Perhaps tables were classified as relations instead of entities?
You can manually add the entities and choose the table they map to in mappings window.
Actually, in my case, it doesn't work because I was using a hierarchyid field as a primary key and EF doesn't work with this field type, so, it didn't import the table, because a valid PK is required.
A possibility is when you're using tables with some different field types, as hierarchy in SQL Server.
Without Primary Key Tables where Skip Automatically on EF, OtherWise You Fix a Value as Not Null.