# .NET SDK Query Predicate builders

Create readable and maintainable Query Predicates using the .NET SDK.

The .NET SDK Query Predicate builder offers a fluent, type-safe interface for building [Query Predicates](/api/predicates/query.md).

For each resource with a query endpoint, the request builders provide a `WithQuery` method. You pass a lambda function that receives the predicate builder. The predicate builder provides a method for each property of the resource as well as all predicate operators.

## Example usage

```csharp title="Query Customers by first name"
// Finds all Customers with the first name "Peter"
projectApiRoot.Customers().Get()
    .WithQuery(q => q.FirstName().Is("Peter"));
```

For more examples, see the [query test class](https://github.com/commercetools/commercetools-dotnet-core-sdk-v2/blob/master/commercetools.Sdk/Tests/commercetools.Sdk.Api.Tests/QueryTests.cs) in the SDK repository.

### Equality comparisons

```csharp title="Apply equality comparisons"
// firstName = "Peter"
projectApiRoot.Customers().Get()
    .WithQuery(q => q.FirstName().Is("Peter"));

// firstName != "Peter"
projectApiRoot.Customers().Get()
    .WithQuery(q => q.FirstName().IsNot("Peter"));

// isEmailVerified = false
projectApiRoot.Customers().Get()
    .WithQuery(q => q.IsEmailVerified().Is(false));

// version != 42
projectApiRoot.Customers().Get()
    .WithQuery(q => q.Version().IsNot(42));
```

### Range comparisons

```csharp title="Apply range comparisons"
// version < 42
projectApiRoot.Customers().Get()
    .WithQuery(q => q.Version().IsLessThan(42));

// version > 42
projectApiRoot.Customers().Get()
    .WithQuery(q => q.Version().IsGreaterThan(42));

// version <= 42
projectApiRoot.Customers().Get()
    .WithQuery(q => q.Version().IsLessThanOrEqual(42));

// version >= 42
projectApiRoot.Customers().Get()
    .WithQuery(q => q.Version().IsGreaterThanOrEqual(42));
```

### Logical operators

Use `And`, `Or`, and `Not` to combine or negate predicate expressions.

```csharp title="Combine predicates with logical operators"
// firstName = "Peter" and version < 42
projectApiRoot.Customers().Get()
    .WithQuery(q => q.FirstName().Is("Peter").And(q.Version().IsLessThan(42)));

// firstName = "Peter" or version < 42
projectApiRoot.Customers().Get()
    .WithQuery(q => q.FirstName().Is("Peter").Or(q.Version().IsLessThan(42)));

// not (firstName = "Peter" and version < 42)
projectApiRoot.Customers().Get()
    .WithQuery(q => q.FirstName().Is("Peter").And(q.Version().IsLessThan(42)).Not());
```

### Collection queries

Use `IsIn` to check whether a field's value is contained in a set of values. Chain `Not` to exclude those values.

```csharp title="Query with IsIn"
// version in (42, 43, 44)
projectApiRoot.Customers().Get()
    .WithQuery(q => q.Version().IsIn(new[] { 42, 43, 44 }));

// version not in (42, 43, 44)
projectApiRoot.Customers().Get()
    .WithQuery(q => q.Version().IsIn(new[] { 42, 43, 44 }).Not());
```

## Related pages

- [Area overview page with navigation](/dev-tooling.md)
- [Previous page: Get started](/dev-tooling/dotnet-sdk-getting-started.md)
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