ElementType
Added in v34.0.0
public Type ElementType { get; }The type of the elements, T.
Class in CsvHelper.Linq
CsvQuery<T>
Added in v34.0.0
A LINQ query over CSV records: its source (CsvQueryable), and the operators applied to it. It runs each time it is enumerated: the CSV reader runs what it can itself (it reads only the members of the records that the query uses, skips rows without parsing them, and filters records before it reads the members that only the rest of the query uses), other LINQ providers run the parts of the query that are theirs, and LINQ to Objects runs the rest.
net10.0, netstandard2.1, netstandard2.0
public class CsvQuery<T> : IOrderedQueryable<T>, IEnumerable<T>, IEnumerable, IOrderedQueryable, IQueryable, IQueryable<T>, ICsvRoot, IAsyncSource<T>net47
public class CsvQuery<T> : IOrderedQueryable<T>, IQueryable<T>, IEnumerable<T>, IEnumerable, IQueryable, IOrderedQueryable, ICsvRoot, IAsyncSource<T>- Namespace
CsvHelper.Linq- Assembly
CsvHelper.Linq.dll- Implements
- IOrderedQueryable<T>, IEnumerable<T>, IEnumerable, IOrderedQueryable, IQueryable, IQueryable<T>, ICsvRoot, IAsyncSource<T>
- Builds
- net10.0 netstandard2.1 netstandard2.0 net47
- Source
- CsvQuery.cs
Remarks
Any LINQ operator can be used. CsvQueryable.Explain tells what a query pushes into the reader.
await foreach over a CsvQuery<T> reads the CSV asynchronously (GetAsyncEnumerator); CsvQueryable.AsCsvAsync does the same for the IQueryable<T> that LINQ operators return, and has asynchronous versions of ToList, Count, First and the others. The queries that operators return also implement IAsyncEnumerable<T>, for code that looks for it, such as the ToListAsync of Entity Framework Core. This class does not, so that the LINQ operators of Queryable and of .NET 10's AsyncEnumerable are not both candidates for a query typed as it.
Properties
Expression
Added in v34.0.0
public Expression Expression { get; }The query: a constant holding the source for the query of all its records, else the operators applied to it.
Property value
Provider
Added in v34.0.0
public IQueryProvider Provider { get; }The provider that creates and runs CSV queries.
Property value
Methods
Explain()
Added in v34.0.0
public CsvQueryPlan Explain()Tells how the query runs without running it: which members of the records it reads, which operators the CSV reader runs, and what it asks other providers for.
Returns
CsvQueryPlan
The plan of the query.
GetAsyncEnumerator(CancellationToken)
Added in v34.0.0
public IAsyncEnumerator<T> GetAsyncEnumerator(CancellationToken cancellationToken = default)Runs the query and reads its results as they are enumerated, reading the CSV asynchronously. When the query has operators that the CSV reader does not run itself, the records it reads are buffered first and the rest of the query runs on them; otherwise the results stream.
Parameters
cancellationTokenCancellationToken- Cancels the reading.
Returns
IAsyncEnumerator<T>
An enumerator of the results; disposing it closes the sources it opened.
GetEnumerator()
Added in v34.0.0
public IEnumerator<T> GetEnumerator()Runs the query and reads its results as they are enumerated.
Returns
IEnumerator<T>
An enumerator of the results; disposing it closes the sources it opened.
Exceptions
- CsvFormatException
- A record cannot be read.
- KeyNotFoundException
- The header lacks a column that the query reads.
ToString()
Added in v34.0.0
public override string ToString()The query, as text.
Returns
string
The source and the operators, such as
file 'orders.csv'.Where(o => (o.Total > 100)).