FilterBy Builder Methods

Seltzr includes several FilterBy methods to simplify the process of comparing request parameters to properties on the model. Every method is tagged with either Query, meaning that a query parameter value will be used for the comparison, or Route, meaning that a route value will be used for the comparison.

Note

There is also a more generic FilterByParameter method which takes in any ParameterRetriever so that this functionality can be extended to other parameters, like headers.

Usage

The following examples show typical usage of the FilterBy methods.

This example demonstrates how to create a GET request that returns only the blog posts belonging to a particular blog.

C#

Copy

app.UseSeltzr<BlogPost>("/blogs/{blogId}/posts", posts => {
	posts
		.FilterByRouteEqual(p => p.BlogId)
		.CanGet();
});

The FilterBy methods, as shown above, can infer the name of the route value to compare to the models' property by camelCasing the property name. Here, blogId is the inferred name of the route value for the BlogId property. However, the name can also be specified explicitly:

C#

Copy

app.UseSeltzr<BlogPost>("/blogs/{blogId}/posts", posts => {
	posts
		.FilterByQueryEqual(p => p.AuthorName, "author")
		.CanGet();
});

For more complex logic, use the FilterByQuery and FilterByRoute methods without Equal. These methods take in an additional lambda parameter that takes in the property value and the parsed parameter value and returns a boolean. This example will only return blog posts that were created after the specified after date.

C#

Copy

app.UseSeltzr<BlogPost>("/blog/posts", posts => {
	posts
		.FilterByQuery(p => p.DateCreated, "after", (prop, param) => prop >= param)
		.CanGet();
});

The above examples will throw an error if the parameter is not present. Most FilterBy methods can have Opt appended to the end of the method name. These methods will not apply the filter if the request parameter is null or not present.

C#

Copy

app.UseSeltzr<BlogPost>("/blog/posts", posts => {
	posts
		.FilterByQueryEqualOpt(p => p.Id)
		.CanGet();
});

Note

To set additional restrictions on the values of request parameters, see Conditions

Warning

FilterBy methods can only compare properties of the following types: int, long, float, double, Guid, decimal, DateTime, bool, and string. If a property with another type is used, a runtime exception will be thrown when attempting to filter.