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grpc.federation.enum APIs

Index

Functions

select

select selects the first enum value if the specified condition is true, and the second enum value if the condition is false. It is used when performing field binding for enums that map multiple enums with an alias.

If you try to return an enum value without using this function, an error will occur due to type mismatch.

e.g.) true ? pkg.EnumType.Enum_VALUE_A : pkgv2.EnumType.ENUM_VALUE_B

grpc-federation: ERROR: <input>:1:6: found no matching overload for '_?_:_' applied to '(bool, pkg.EnumType(int), pkgv2.EnumType(int))'
 | true ? pkg.EnumType.value('ENUM_VALUE_A') : pkgv2.EnumType.value('ENUM_VALUE_B')
 | .....^

Parameters

select(cond bool, <first-enum-value>, <second-enum-value>) grpc.federation.private.EnumSelector

  • cond: condition to select enum value
  • first-enum-value: first enum value. this is selected if the condition is true.
  • second-enum-value: second enum value. this is selected if the condition is false.

Examples

grpc.federation.enum.select(true, pkg.EnumType.ENUM_VALUE_A, pkgv2.EnumType.ENUM_VALUE_B)

<enum-fqdn>.name

For all enum types, you can use the name method to obtain the name of the enum value as a string.

Parameters

pkg.EnumType.name(<enum-value>) string

  • <enum-value>: int or enum typed value

Examples

In the following case, "ENUM_VALUE_1" ( string typed value) is returned.

foo.EnumType.name(foo.EnumType.ENUM_VALUE_1)

package foo;

enum EnumType {
  ENUM_VALUE_UNKNOWN = 0;
  ENUM_VALUE_1 = 1;
}

<enum-fqdn>.value

For all enum types, you can use the value method to obtain the enum typed value from name.

Parameters

pkg.EnumType.value(enumValueName string) EnumValue

  • enumValueName: name of the enum value
  • EnumValue: enum typed value. This value can be used as an argument for the select function

Examples

In the following case, foo.EnumType.ENUM_VALUE_1 ( enum typed value) is returned.

foo.EnumType.value('ENUM_VALUE_1')

package foo;

enum EnumType {
  ENUM_VALUE_UNKNOWN = 0;
  ENUM_VALUE_1 = 1;
}

<enum-fqdn>.from

For all enum types, you can use the from method to obtain the enum typed value from int value.

Parameters

pkg.EnumType.from(enumValue int) EnumValue

  • enumValue: int typed value of the enum value
  • EnumValue: enum typed value. This value can be used as an argument for the select function

Examples

In the following case, foo.EnumType.ENUM_VALUE_1 ( enum typed value) is returned.

Note

Here, you might be confused by the difference between foo.EnumType.ENUM_VALUE_1 appearing in the expression and the returned foo.EnumType.ENUM_VALUE_1 value. As a basic principle, CEL treats enum values as int types when specified directly. The from method is used to convert this to a typed enum value. Although the result looks the same, it is actually typed and can be used as an argument for the select function.

foo.EnumType.from(foo.EnumType.ENUM_VALUE_1)

package foo;

enum EnumType {
  ENUM_VALUE_UNKNOWN = 0;
  ENUM_VALUE_1 = 1;
}

<enum-fqdn>.attr

If you use attr to hold multiple name-value pairs corresponding to an enum value, you can get value from name.

Parameters

pkg.EnumType.attr(enumValue EnumValue, name string) string

  • enumValue: the enum value
  • name: string value to search attribute.

Examples

In the following case, Foo.text value is foo.

package mypkg;

message Foo {
  option (grpc.federation.message) = {
    def { name: "v" by: "Type.value('VALUE_1')" }
  };
  string text = 1 [(grpc.federation.field).by = "Type.attr(v, 'attr_x')"];
}

enum Type {
  VALUE_1 = 1 [(grpc.federation.enum_value).attr = {
    name: "attr_x"
    value: "foo"
  }];
  VALUE_2 = 2 [(grpc.federation.enum_value).attr = {
    name: "attr_x"
    value: "bar"
  }];
}