Question
I'll keep it simple. I have an API endpoint that receives 0 to 3 parameters. The get method look like this:
[HttpGet("filtrar")]
public ActionResult<List<TipoDocumento>> GetAllPorFiltro(string sigla, int? status, string descricao)
{
return _tipoDocumentoRepositorio.GetAllByFilter(????);
}
The _tipoDocumentoRepositorio is an interface that has DI, and the method GetAllByFilter() in the class that implements it looks like this:
public List<T> GetAllByFilter(Expression<Func<T, bool>> filter)
{
return _someContexto.Set<T>()
.Where(filter)
.ToList();
}
The fact is: even though I put a function on ???? (like
f => f.Sigla.Equals(sigla)
), it keeps me returning an empty List. What am I doing wrong? Or what else should I do to make it work?
Obs: I can't put all of the code here cause it's not mine, but I can argue. To be sure: I'm using EF (and Migration and sort, I'm new in C#). And any links to other SO question that may answer my question is welcomed as well. Thanks in advance.
Accepted Answer
Change your GetAllByFilter to just GetAll() and return just IQueriable<T>
Create an extension method:
public static IQueryable<T> WhereIf<T>(
this IQueryable<T> source, bool condition,
Expression<Func<T, bool>> predicate)
{
if (condition)
return source.Where(predicate);
else
return source;
}
Use it like that:
[HttpGet("filtrar")]
public ActionResult<List<TipoDocumento>> GetAllPorFiltro(string sigla, int? status, string descricao)
{
var res = _tipoDocumentoRepositorio
.GetAll()
.WhereIf(!String.IsNullOrEmpty(sigla), q => q.sigla == sigla)
.WhereIf(status.HasValue, q => q.sigla == sigla.Value)
.WhereIf(!String.IsNullOrEmpty(descricao), q => q.descricao == descricao)
.ToList();
...
}
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