Get()

This operation issues a query with primary keys and returns a list of records.

Status Get(const GetRequest& request, GetResponse& response)

Request Syntax

auto request = GetRequest()
    .WithDatabaseName(db_name)
    .WithCollectionName(collection_name)
    .WithPartitionNames(partition_names)
    .WithOutputFields(output_field_names)
    .WithConsistencyLevel(consistency_level)
    .WithIDs(id_array);

REQUEST METHODS:

• WithDatabaseName(const std::string& db_name)

  Sets the target database name. The default database applies if it is empty.

• WithCollectionName(const std::string& collection_name)

  Sets the name of the collection.

• WithPartitionNames(std::set<std::string>&& partition_names)

  Sets the names of the partitions. If it is empty, the default partition applies.

• AddPartitionName(const std::string& partition_name)

  Adds a partition name.

• WithOutputFields(std::set<std::string>&& output_field_names)

  Sets the output field names.

• AddOutputField(const std::string& output_field)

  Adds an output field.

• WithConsistencyLevel(ConsistencyLevel consistency_level)

  Sets the consistency level.

• WithIDs(std::vector<int64_t>&& id_array)

  Sets an ID array.

RETURNS:

Status with GetResponse

Check status.IsOk() to confirm success.

FieldData

This is the template class that represents column-based data for a single field. Concrete aliases cover every supported data type. Instances of the concrete types are used when inserting data via InsertRequest::WithRowsData() or reading query/search results via QueryResults::OutputField() and SingleResult::OutputField().

// Base abstract interface (not instantiated directly)
class Field {
    const std::string& Name() const;
    DataType Type() const;
    DataType ElementType() const;   // for ARRAY fields only
    virtual size_t Count() const = 0;
    virtual void Reserve(size_t count) = 0;
};

using FieldDataPtr = std::shared_ptr<Field>;

// Template class
template <typename T, DataType Dt>
class FieldData : public Field {
    explicit FieldData(std::string name);
    FieldData(std::string name, const std::vector<T>& data);
    FieldData(std::string name, const std::vector<T>& data, const std::vector<bool>& valid_data);

    StatusCode Add(const T& element);
    StatusCode AddNull();
    StatusCode Append(const std::vector<T>& elements);
    size_t Count() const;
    void Reserve(size_t count);
    virtual const std::vector<T>& Data() const;
    virtual T Value(size_t i) const;
    virtual bool IsNull(size_t i) const;
    virtual const std::vector<bool>& ValidData() const;
};

QueryResults

This class holds the column-based result data returned by a Query() call. Access it via Results() on a QueryResponse object.

const QueryResults& results = response.Results();

METHODS:

• FieldDataPtr OutputField(const std::string& name) const

  Returns the named output field as a FieldDataPtr. Cast to the concrete type with std::dynamic_pointer_cast<Int64FieldData>(results.OutputField("id")).

• const std::vector<FieldDataPtr>& OutputFields() const

  Returns all output fields in the order they were returned by the server.

• const std::set<std::string>& OutputFieldNames() const

  Returns the set of output field names that were requested in the query.

• Status OutputRows(EntityRows& rows) const

  Converts all result rows to a vector of JSON-like row maps and stores them in rows.

• Status OutputRow(int i, EntityRow& row) const

  Converts the row at index i to a JSON-like row map.

• uint64_t GetRowCount() const

  Number of rows returned. When the query uses count(*), this returns the aggregate count.

EXCEPTIONS:

• StatusCode

  Check status.Code() and status.Message() for error details.

Field-data type aliases

Category	Concrete types	Representation and notes
Scalar	BoolFieldData, Int8FieldData, Int16FieldData, Int32FieldData, Int64FieldData, FloatFieldData, DoubleFieldData, VarCharFieldData, JSONFieldData, GeometryFieldData, TimestamptzFieldData	Aliases of FieldData<T, DataType::...>. Geometry uses WKT strings; timestamptz uses ISO-8601 strings.
Vector	FloatVecFieldData, Float16VecFieldData, BFloat16VecFieldData, Int8VecFieldData, SparseFloatVecFieldData, BinaryVecFieldData	Dense and sparse vector containers. BinaryVecFieldData is a derived class with string conversion helpers.
Array and struct	ArrayBoolFieldData, ArrayInt8FieldData, ArrayInt16FieldData, ArrayInt32FieldData, ArrayInt64FieldData, ArrayFloatFieldData, ArrayDoubleFieldData, ArrayVarCharFieldData, StructFieldData	Aliases of ArrayFieldData<T, Et>; each entity row is a vector. Struct values use JSON storage.
Shared pointers	XxxFieldDataPtr	Each concrete field-data type has a corresponding std::shared_ptr<XxxFieldData> alias.

Example

#include "milvus/MilvusClientV2.h"
auto client = milvus::MilvusClientV2::Create();

milvus::ConnectParam connect_param{"http://localhost:19530", "root:Milvus"};
auto status = client->Connect(connect_param);
if (!status.IsOk()) {
    std::cout << status.Message() << std::endl;
}

std::vector<int64_t> ids = {5, 1, 10, 8};
auto request = milvus::GetRequest()
                   .WithCollectionName(collection_name)
                   .WithIDs(std::move(ids))
                   .AddOutputField(field_vector);

milvus::GetResponse response;
status = client->Get(request, response);
if (!status.IsOk()) {
    std::cout << status.Message() << std::endl;
}

auto query_results = response.Results();
milvus::EntityRows output_rows;
status = query_results.OutputRows(output_rows);
if (!status.IsOk()) {
    std::cout << status.Message() << std::endl;
}
std::cout << "Get results:" << std::endl;
for (const auto& row : output_rows) {
    std::cout << "\t" << row << std::endl;
}