Aggregation Expression - $switch

Function Build

Build $switch with the Switch function from the aggregation package.

// bson.D{bson.E{Key:"grade", Value:bson.D{bson.E{Key:"$switch", Value:bson.D{bson.E{Key:"branches", Value:bson.A{...}}, bson.E{Key:"default", Value:"B"}}}}}}
result := aggregation.Switch("grade", []aggregation.CaseThen{{Case: aggregation.GteWithoutKey("$score", 90), Then: "A"}}, "B")

Method Build (Builder)

Build $switch with the Switch method from aggregation.NewBuilder().

// bson.D{bson.E{Key:"grade", Value:bson.D{bson.E{Key:"$switch", Value:bson.D{bson.E{Key:"branches", Value:bson.A{...}}, bson.E{Key:"default", Value:"B"}}}}}}
result := aggregation.NewBuilder().
    Switch("grade", []aggregation.CaseThen{{Case: aggregation.GteWithoutKey("$score", 90), Then: "A"}}, "B").
    Build()

Build Without Key

When an expression needs to be passed as an argument to another expression, use a WithoutKey variant to build an expression fragment without an output field name.

SwitchWithoutKey

Function build:

// bson.D{bson.E{Key:"$switch", Value:bson.D{bson.E{Key:"branches", Value:bson.A{...}}, bson.E{Key:"default", Value:"B"}}}}
expr := aggregation.SwitchWithoutKey([]aggregation.CaseThen{{Case: aggregation.GteWithoutKey("$score", 90), Then: "A"}}, "B")

Method build (Builder):

// bson.D{bson.E{Key:"$switch", Value:bson.D{bson.E{Key:"branches", Value:bson.A{...}}, bson.E{Key:"default", Value:"B"}}}}
expr := aggregation.NewBuilder().
    SwitchWithoutKey([]aggregation.CaseThen{{Case: aggregation.GteWithoutKey("$score", 90), Then: "A"}}, "B").
    Build()