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Query Builder API¶

The CollectionBuilder provides a fluent interface for building OData query options.

Filter expressions¶

String expressions¶

client.Collection("Products").
    Filter("Price gt 10 and Category eq 'Electronics'").
    List(ctx, &products)

Lambda DSL¶

Use the type-safe lambda helpers to avoid string concatenation:

import "github.com/jhonsferg/traverse/query"

client.Collection("Products").
    FilterExpr(
        query.And(
            query.Field("Price").Gt(10),
            query.Field("Category").Eq("Electronics"),
        ),
    ).
    List(ctx, &products)

Lambda filter functions¶

Function	OData equivalent
`query.Field(name).Eq(v)`	`field eq v`
`query.Field(name).Ne(v)`	`field ne v`
`query.Field(name).Gt(v)`	`field gt v`
`query.Field(name).Ge(v)`	`field ge v`
`query.Field(name).Lt(v)`	`field lt v`
`query.Field(name).Le(v)`	`field le v`
`query.Field(name).Contains(s)`	`contains(field,'s')`
`query.Field(name).StartsWith(s)`	`startswith(field,'s')`
`query.Field(name).EndsWith(s)`	`endswith(field,'s')`
`query.And(a, b)`	`a and b`
`query.Or(a, b)`	`a or b`
`query.Not(a)`	`not a`
`query.Any(nav, lambda)`	`nav/any(x: lambda)`
`query.All(nav, lambda)`	`nav/all(x: lambda)`

Select¶

client.Collection("Products").
    Select("ProductID", "ProductName", "UnitPrice").
    List(ctx, &products)
// $select=ProductID,ProductName,UnitPrice

Expand¶

client.Collection("Orders").
    Expand("Customer", "OrderDetails/Product").
    List(ctx, &orders)
// $expand=Customer,OrderDetails/Product

Expand with nested options (OData v4)¶

client.Collection("Orders").
    ExpandWith("OrderDetails", query.ExpandOptions{
        Select: []string{"Quantity", "UnitPrice"},
        Filter: query.Field("Quantity").Gt(5),
        OrderBy: "UnitPrice desc",
    }).
    List(ctx, &orders)
// $expand=OrderDetails($select=Quantity,UnitPrice;$filter=Quantity gt 5;$orderby=UnitPrice desc)

OrderBy¶

// Ascending
client.Collection("Products").OrderBy("ProductName").List(ctx, &p)

// Descending
client.Collection("Products").OrderBy("Price desc").List(ctx, &p)

// Multiple fields
client.Collection("Products").OrderBy("Category", "Price desc").List(ctx, &p)

Pagination¶

// Manual offset/limit
client.Collection("Products").Top(20).Skip(40).List(ctx, &p)

// Typed paginator
paginator, _ := client.Collection("Products").
    OrderBy("ProductID").
    Paginate[Product](ctx, traverse.PageOptions{Size: 20})

Apply ($apply - aggregation)¶

client.Collection("Sales").
    Apply("groupby((Region),aggregate(Amount with sum as Total))").
    List(ctx, &summary)

Count¶

result, err := client.Collection("Products").Count().List(ctx, &products)
fmt.Println(result.Count) // total matching records

See also¶