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Map rules ​

MapRules describe the rules applied to map values.

min_pairs ​

Specifies the minimum number of key-value pairs allowed. If the field has fewer key-value pairs than specified, an error message is generated.

map.min_pairs example

proto
message MyMap {
  // The field `value` must have at least 2 key-value pairs.
  map<string, string> value = 1 [(buf.validate.field).map.min_pairs = 2];
}

max_pairs ​

Specifies the maximum number of key-value pairs allowed. If the field has more key-value pairs than specified, an error message is generated.

map.max_pairs example

proto
message MyMap {
  // The field `value` must have at most 3 key-value pairs.
  map<string, string> value = 1 [(buf.validate.field).map.max_pairs = 3];
}

keys ​

Specifies the rules to be applied to each key in the field.

Note that map keys are always considered populated. The required rule does not apply.

map.keys example

proto
message MyMap {
  // The keys in the field `value` must follow the specified rules.
  map<string, string> value = 1 [(buf.validate.field).map.keys = {
    string: {
      min_len: 3
      max_len: 10
    }
  }];
}

values ​

Specifies the rules to be applied to the value of each key in the field. Message values will still have their validations evaluated unless skip is specified here.

Note that map values are always considered populated. The required rule does not apply.

map.values example

proto
message MyMap {
  // The values in the field `value` must follow the specified rules.
  map<string, string> value = 1 [(buf.validate.field).map.values = {
    string: {
      min_len: 5
      max_len: 20
    }
  }];
}