You can override the DbContext.OnModelCreating method and use a parameter modelBuilder of type ModelBuilder to configure domain classes. The issue is that you are removing all conventions on load, then using Fluent API. Precedence is given to configuration through the fluent API followed by data annotations and then conventions. When I add: Looks like, if you start Fluent API, you must put everything there. Fluent offers features not exposed through DA. With the Database First approach an EDMX file is created by the EF Designer and (usually) embedded in the application assembly. Is this documented anywhere? This article is designed to demonstrate how to use the fluent API to configure properties. Then I thought, what if I'm doing something wrong and EF is saving my butt? Unfortunately, once you’ve created a sizeable code footprint, going back and adding missing documentation after the fact is a Herculean task. In Entity Framework Core, the ModelBuilder class acts as a Fluent API. For additional information regarding the use of Data Annotations and the Code First Fluent API refer to the MSDN Entity Framework documentation. 7 comments Labels. Comments. Fluent API configuration also facilitates cleaner code, in that the configuration can be kept separate from the domain classes. Code First approach provides two methods to configure the domain classes of application: using Data Annotations and using the Fluent API. The thing to keep in mind is that no matter if you fluent configure or if you use data annotations it is still running those against the data in the object. We could use a standard data annotation: However, we’re not going to do this. MinLength is the only configuration that can be achieved using Data Annotation but has no counterpart in the Fluent API configurations. In our experience, it seems that the two configuration styles can be mixed freely, with fluent configuration overriding DataAnnotations. Data annotations and the fluent API can be used together, but precedence of Fluent API > data annotations > default conventions. Attaching the config fluently increases slightly the overhead of creating the context but very slightly as … JavaFX dynamic TableView is not showing data from the database, Error inflating class com.google.android.material.textfield.TextInputLayout, Never ending periodic recovery of heuristic participants. Fluent API configures the following aspect of a model in Entity Framework 6: Model-wide Configuration: Configures the default Schema, entities to be excluded in mapping, etc. I personally haven't ran into any issues with mixing the code first fluent api and data … Out of the box, this will ca… MinLength will be used for EF validation without impacting the database. Separate Configuration Classes. Mixing data annotations with fluent API throws EntityType has no key defined for every class in context. Data Annotations work across multiple ORMs. But the issue is that Fluent … A detailed list of Code First conventions is available in the API Documentation. These two approaches differ fundamentally in the way DbContext behaves when the application is run. Which over time led me to use pretty much straight fluent configuration (also freeing my my objects of any ties with the Db 'state of mind')... IMO it is 'safer' but only in a way that you can do more and control Define the key for this EntityType. closed-by-design. We will discuss the preferred alternative to Data Annotations and implement it in an ASP.Net core API. How to send email to multiple recipients using python smtplib? Active 2 … http://msdn.microsoft.com/en-us/data/jj591583.aspx, (Part 1) You can freely mix use of annotations and Fluent API. Here's a few references to case studies on the subject to ease your mind. How to crop the biggest object in image with python opencv? Fluent works when you can't modify the classes. For example, if one of the entity classes is called “User” but the corresponding table in the database is called “t_userdata”, then this mapping is included in the EDMX file. Another way to configure domain classes is by using Entity Framework Fluent API. Fluent API. DbModelBuilder You can override the DbContext.OnModelCreating method and use a parameter modelBuilder of type DbModelBuilder to configure domain classes. I’ll demonstrate Code First DataAnnotations with a simple pair of classes: Blog and Post.As they are, the Blog and Post classes conveniently follow code first convention and require no tweaks to enable EF compatability. I use both, wherever each is appropriate, in a project currently. (Direct from the EF team) Data Annotation Attributes ; Fluent API; Data Annotations Attributes. I don't think it's a risk - as both things have equivalent counterparts for the most of it. But, personally, when I run into some sort of issues around structuring my entities - first thing I do is to remove annotations if any - and move all to fluent. Data annotations and the fluent API can be used together, but precedence of Fluent API > data annotations > default conventions. Let’s say we have started to build a web api to add new customers: Our NewCustomermodel is: We also have an action filter which will handle validation on the models and return a 400 if they are invalid: Startup.ConfigureServiceslooks like this to wire everything up: So, let’s say we want to make CustomerName a required field in the POST method on the newCustomermodel. And here’s why: It is easy to see which validation rule is related to which property because it is placed right above the property and it is quite self-explanatory Is there any risk to doing this mixed configuration? For more information see Data Annotations, Fluent API - Relationships, Fluent API - Types & Properties and Fluent API with VB.NET. We have already discussed a lot about Data Annotations. things exactly as you'd want them. Through the use of Data Annotations or the Entity Framework Fluent API you may control the table name, as well as the table owner. The fluent API is considered a more advanced feature and we would recommend using Data Annotations unless your requirements require you to use the fluent API. So for example, you can have a data annotation with a string length of 50 and then override that with the fluent API such that the database created as a column which allows a string length of 200. Data Annotations permit you to explicitly mark a class property with one or more attributes, whereas the Code First Fluent API permits you to use code rather than attributes to achieve the same goal. And I don't even know that. I also wondered if there would be any crossover pain and I can honestly say I have yet to find any. They each have strengths and weaknesses. Dependent entity: This is the entity that contains the foreign key property(s). Entity Framework gives precedence to Fluent API over Data Annotations attributes. But in my opinion you reach the limitations of DataAnnotations very quickly (except perhaps for extremely simple object models). A Configuration Convention is a way to configure entities without overriding the default behavior provided in the Fluent API. These attributes are not only for EF but also used in ASP.NET web form or MVC and so, included in a separate namespace System.ComponentModel.DataAnnotations. Fluent API is an advanced way of specifying model configuration that covers everything that data annotations can do in addition to some more advanced configuration not possible with data annotations. consistent and in one place. 来源:https://stackoverflow.com/questions/15705435/mixing-fluent-api-and-dataannotations-in-ef-code-first, COPYRIGHT 2019 天府资讯. Sometimes referred to as the 'child' of the relationship Data Annotations let you actually see how your ORM is configured without digging through a multi- thousand line function. Item does have [Key] attribute! Such mappin… I personally haven't ran into any issues with mixing the code first fluent api and data annotations. 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