Mini ORM PetaPoco
PetaPoco - Mapping One-to-Many and Many-to-One Relationships If there is a poco object, to make sure it is in the database or a new record. The most recent scenario involved loading hierarchical data without Multi-Poco Mapping Feature The PetaPoco – Mapping One-to-Many and using the Multi- Poco Mapping Feature for loading one-to-many relationships. Mapping Complex Types to/from the DB with PetaPoco .. In the prior PetaPoco post, I started to dig into many-to-one relationships a little.
The T4 template will automatically generate the Records. The return value is a PagedFetch object: When constructing paging controls needed. In PetaPoco this is a Fetch instead of a Query.
Less Than Dot - Blog - Mapping Complex Types to/from the DB with PetaPoco
Add a IEnumerable version is also very simple, but taking into account the size of the result set paging is determined, so there's no need to add. The story behind the: I always feel that build paging query is boring, this generally involves two different but very similar SQL statements: Then talked about how to deal with the similarities and differences between MySQL and SQL Server paging query, in order to support different database query, use different.
Database method refers to the column name, not the name of the attribute mapping. Sometimes run a query not only returns the columns in the table, will be calculated or connecting column. We need to query the result can fill these columns, but in the Update and Insert operations to ignore them.
For this purpose, added a new [ResultColumn] attribute. Suppose you have a categories table, you would like to be able to retrieve the number of posts in each category.
Save c ; But you can also use it to capture the results of join: Not PetaPoco generated from the select statements automatically generated column in including them as in the last example of SingleOrDefault command. This will define the attributes in an attempt to cause abnormal.
Now PetaPoco can automatically do this conversion. When the long is converted to int when the value is out of range, an exception is thrown. IDataReaders destruction The last version of a bug, Fetch or Query method after data readers not be destroyed.
We have fixed this mistake. SQL is an embedded resource script for initialization and cleanup.Laravel 5.4 Tutorial - Eloquent One to Many Relationship - Part 7- Bitfumes
The use of each test case itself is simple and direct. There are test cases on SQL builder function. The main test can be passed, no problem. Test cases are included in the GitHub library, but NuGet doesn't.
Many to One relationships with PetaPoco
Some Minor PetaPoco Improvements http: The return type is always forget FetchPage or PagedFetch when in use. Now the paging method and return type, now called Page. This is all the info we need to persist this relationship in the database. Creating these records is a one-liner if you have the article and tag ids: Execute "insert into articleTag values 0, 1 ", article.
Id, tagId ; There is a bit more complexity when it comes to reading article pocos and their tags. There are two ways of doing it: Loop through each article and retrieve its tags Assign the list of tags to each article in the loop. Imagine it if we were pulling back 50 articles.
Hierarchical Data with PetaPoco Multi-Poco Mapping
That would be 51 database round trips when all we really need is 1. You can tell this is a many-to-many relationship by the double joining first on the articleTag then on tag itself. The results that come back to PetaPoco look like this: As you can see there is a fair bit of duplication here and this is a trade off you will want to think carefully about.
The trade off is between the number of database round trips number of queries and result set efficiency network traffic from the sql server to the web server or service layer server. It is best to have as few database round trips as possible. But on the other hand it is better to have lean result sets too. If I was writing a real blogging app I would think long and hard about a single joined query like this because the body content, which could be thousands of bytes, would be returned as many times as there are tags against the blog post.
I would almost certainly use a stored procedure to return multiple result sets so there is only one database round trip. Document databases suit this type of arrangement.
The tags would be embedded in the article document and would still be indexable.