[TDR Generic Table][Go SDK] Get a Record

1. Interface Description

Get a record from a database table. Getting a record that does not exist will generate errors

2. Version Requirements

This interface is provided in all versions without special requirements.

3. Preparations

Refer to Preparation document to complete the preparation before using this interface and create the following TDR Generic table. service_info table service_info.xml

<?xml version="1.0" encoding="UTF-8" standalone="yes" ?>
<metalib name="service_info" tagsetversion="1" version="1">
    <struct name="service_info" version="1" primarykey="gameid,envdata,name,expansion" splittablekey="gameid" >
        <entry name="gameid"               type="string"     size="128" desc="gameapp id"/>
        <entry name="envdata"            type="string"     size="1024" desc="environment information"/>
        <entry name="name"            type="string"     size="1024" desc="name"/>
        <entry name="expansion"            type="string"   size="1024"           desc="expansion field"/>
        <entry name="filterdata"            type="string"     size="1024" desc="filter condition"/>
        <entry name="updatetime"           type="uint64"                  desc="latest update time, unit: ms"/>
        <entry name="inst_max_num"           type="uint64"                  desc="maximum number of instances"/>
        <entry name="inst_min_num"           type="uint64"                  desc="minimum number of instances"/>
        <entry name="routeinfo_len"      type="uint"     defaultvalue="0" desc="route information length" />
        <entry name="routeinfo"      type="char"     count="1024" refer="routeinfo_len" desc="route information length" />
        <index name="index_gameid_envdata_name" column="gameid,envdata,name" />
        <index name="index_gameid_envdata" column="gameid,envdata" />
        <index name="index_gameid_name" column="gameid,name" />
        <index name="index_gameid" column="gameid" />
    </struct>
</metalib>

Get the following information after the preparation. These details will be used by the SDK:

1. Directory server address list
2. App ID
3. App access password
4. Game zone ID
5. Table name

4. Example Code

Basic execution process of example code:

1. Define table configuration parameters
2. Set log configuration;
3. Create a client;
4. Send a request and process the response;
5. Destroy the client.

Example of client initialization:

package main

import (
    "fmt"
    "git.woa.com/gcloud_storage_group/tcaplus-go-api"
)

// Define table configuration parameters
const (
  AppId                = uint64(2)
  ZoneId               = uint32(3)
  DirUrl               = "tcp://x.x.x.x:xxxx"
  Signature            = "xxxxxxxxxxxxx"
  TableName            = "service_info"
)

var client *tcaplus.Client

func main() {
  // Create a client
  client = tcaplus.NewClient()
  // Set log configuration and the log level in the logconf.xml file
  if err := client.SetLogCfg("./logconf.xml"); err != nil {
      fmt.Println(err.Error())
      return
  }

  // Connect to the TcaplusDB backend
  err := client.Dial(AppId, []uint32{ZoneId}, DirUrl, Signature, 60)
  if err != nil {
      fmt.Printf("init failed %v\n", err.Error())
      return
  }
  fmt.Printf("Dial finish\n")
  getExample()

  // Call Close to destroy the client when the program exits
  client.Close()
}

4.1 Example Code for Synchronous Call (Recommended)

The synchronous call coding is the simplest, and it can be implemented through multiple concurrent processes. Example Directory

package main

import (
  "fmt"
  "git.woa.com/gcloud_storage_group/tcaplus-go-api/example/TDR/async/service_info"
)

func getExample() {
    //Apply for a tdr structure and assign the Key value. It is preferable to use the NewXXX function of the tdr pkg, which sets the members to the tdr default value defined by tdr.
    // Do not create new structures by yourself; otherwise, there is a risk of panic if some structures are not initialized
    data := service_info.NewService_Info()
    data.Gameid = "dev"
    data.Envdata = "oa"
    data.Name = "com"
    // Synchronously send the request and receive the response, and the response message will be overwritten in the data
    err := client.DoGet(TableName, data, nil)
    if err != nil {
        fmt.Println(err.Error())
        return
    }
    fmt.Println(data)
}

4.2 Example Code 2 for Synchronous Call (Recommended)

The synchronous call mode of this example is similar to that of the C++ interface, and the request needs to be created and the response needs to be parsed. Example Directory

package main

import (
  "fmt"
  "git.woa.com/gcloud_storage_group/tcaplus-go-api/example/TDR/async/service_info"
  "git.woa.com/gcloud_storage_group/tcaplus-go-api/protocol/cmd"
  "git.woa.com/gcloud_storage_group/tcaplus-go-api/terror"
  "time"
)

func getExample() {
  // Create a request
  req, err := client.NewRequest(ZoneId, TableName, cmd.TcaplusApiGetReq)
  if err != nil {
    fmt.Printf("getExample NewRequest TcaplusApiGetReq failed %v\n", err.Error())
    return
  }

  //Add a request record (the index is only supported in the list table and is not verified in the generic). 
  rec, err := req.AddRecord(0)
  if err != nil {
    fmt.Printf("getExample AddRecord failed %v\n", err.Error())
    return
  }

  //Apply for a tdr structure and assign the Key value. It is preferable to use the NewXXX function of the tdr pkg, which sets the members to the tdr default value defined by tdr.
  // Do not create new structures by yourself; otherwise, there is a risk of panic if some structures are not initialized
  data := service_info.NewService_Info()
  data.Gameid = "dev"
  data.Envdata = "oa"
  data.Name = "com"
  //Set the tdr data to the request record
  if err := rec.SetData(data); err != nil {
    fmt.Printf("SetData failed %v\n", err.Error())
    return
  }

  // Use the client to send the request and receive the response synchronously
  if resp, err := client.Do(req, time.Duration(2*time.Second)); err != nil {
    fmt.Printf("recv err %s\n", err.Error())
    return
  } else {
    // Get the error code of the response message
    tcapluserr := resp.GetResult()
    if tcapluserr != 0 {
      fmt.Printf("response ret errCode: %d, errMsg: %s", tcapluserr, terror.GetErrMsg(tcapluserr))
      return
    }

    // Get records from the response message
    fmt.Printf("getExample response success record count %d\n", resp.GetRecordCount())
    for i := 0; i < resp.GetRecordCount(); i++ {
      record, err := resp.FetchRecord()
      if err != nil {
        fmt.Printf("FetchRecord failed %s\n", err.Error())
        return
      }
      //Get records through GetData
      data := service_info.NewService_Info()
      if err := record.GetData(data); err != nil {
        fmt.Printf("record.GetData failed %s\n", err.Error())
        return
      }
      fmt.Printf("getExample response record data %+v, route: %s\n",
        data, string(data.Routeinfo[0:data.Routeinfo_Len]))
    }
  }
}

4.3 Example Code for Asynchronous Call (Recommended)

Asynchronous sending can use fewer processes to achieve greater concurrency. The coding is relatively complex. Example Directory

package main

import (
  "fmt"
  "git.woa.com/gcloud_storage_group/tcaplus-go-api/example/TDR/async/service_info"
  "git.woa.com/gcloud_storage_group/tcaplus-go-api/logger"
  "git.woa.com/gcloud_storage_group/tcaplus-go-api/protocol/cmd"
  "git.woa.com/gcloud_storage_group/tcaplus-go-api/terror"
  "strconv"
  "time"
)

func getExample() {
  wg := sync.WaitGroup{}
  wg.Add(1)
  // Process the response message in another coroutine
  go func() {
    defer wg.Done()
    for {
      // If resp and err are both nil, there is no response in the response pool
      resp, err := client.RecvResponse()
      if err != nil {
        logger.ERR("RecvResponse error:%s", err)
        continue
      } else if resp == nil {
        time.Sleep(time.Microsecond * 5)
        continue
      }

      //Bring back the asynchronous ID of the request
      fmt.Printf("resp success, AsyncId:%d\n", resp.GetAsyncId())
      tcapluserr := resp.GetResult()
      if tcapluserr != 0 {
        fmt.Printf("response ret %s\n",
          "errCode: "+strconv.Itoa(tcapluserr)+", errMsg: "+terror.ErrorCodes[tcapluserr])
        return
      }
      //The response contains the obtained record
      fmt.Printf("response success record count %d\n", resp.GetRecordCount())
      for i := 0; i < resp.GetRecordCount(); i++ {
        record, err := resp.FetchRecord()
        if err != nil {
          fmt.Printf("FetchRecord failed %s\n", err.Error())
          return
        }
        //Get records through GetData
        data := service_info.NewService_Info()
        if err := record.GetData(data); err != nil {
          fmt.Printf("record.GetData failed %s\n", err.Error())
          return
        }
        fmt.Printf("response record data %+v, route: %s\n",
          data, string(data.Routeinfo[0:data.Routeinfo_Len]))
      }
      return
    }
  }()

  //Create a Get request
  req, err := client.NewRequest(ZoneId, TableName, cmd.TcaplusApiGetReq)
  if err != nil {
    fmt.Printf("NewRequest TcaplusApiGetReq failed %v\n", err.Error())
    return
  }

  //Set the asynchronous request ID, through which the response and request are mapped
  req.SetAsyncId(667)
  //Add a request record (the index is only supported in the list table and is not verified in the generic).
  rec, err := req.AddRecord(0)
  if err != nil {
    fmt.Printf("AddRecord failed %v\n", err.Error())
    return
  }

  //Apply for a tdr structure and assign the Key value. It is preferable to use the NewXXX function of the tdr pkg, which sets the members to the tdr default value defined by tdr.
  // Do not create new structures by yourself; otherwise, there is a risk of panic if some structures are not initialized
  data := service_info.NewService_Info()
  data.Gameid = "dev"
  data.Envdata = "oa"
  data.Name = "com"
  //Set the tdr data to the request record
  if err := rec.SetData(data); err != nil {
    fmt.Printf("SetData failed %v\n", err.Error())
    return
  }

  // Send a request asynchronously
  if err := client.SendRequest(req); err != nil {
    fmt.Printf("SendRequest failed %v\n", err.Error())
    return
  }
  wg.Wait()
}

5. Method Description in Request Object

Note: Other methods of the request object are not listed here, which means that this method is not required in the scenario of querying data. Misuse may result in errors.

/**
  @brief: add a record to the request.
  @param [IN] index: used for List operations, and it is usually >=0, indicating the Index of the Record in the List.
                            For Generic operations, the index is meaningless, just set 0
  @retval record.Record: return the record pointer
  @retval error: error code
**/
AddRecord(index int32) (*record.Record, error)

/**
@brief: set the asynchronous transaction ID of the request, and the API will bring its value back through the response message unchanged
@param  [IN] asyncId: asynchronous transaction ID of the request
**/
SetAsyncId(id uint64)

/**
@brief: set the general flag bit of the request. Multiple values can be set at the same time through the "bit or" operation
@param  [IN]  flag: value of the request flag bit
@retval 0: setting successful
@retval < 0 failed and returned the corresponding error code. Usually because it is not initialized.
@note: valid flag bits include:
*  TCAPLUS_FLAG_FETCH_ONLY_IF_MODIFIED:
*      "Fetch only if modified" flag bit: Before starting a read operation, the user code carries the version number of the locally buffered data through TcaplusServiceRecord::SetVersion()
*      and sets this flag. When the storage end detects that the current data is consistent with the API buffered data version,
*      it indicates that the record has not been modified and that the API buffered data is the latest. As a result, it will not return the actual data,
*      but only the error code of TcapErrCode::COMMON_INFO_DATA_NOT_MODIFIED
*
*      After this flag bit is set in the request, the response should first be received through TcaplusServiceResponse::GetFlags() to find out
*      whether the TCAPLUS_FLAG_FETCH_ONLY_IF_MODIFIED flag was set when sending the request.
*
*      Only the following requests support setting this flag:
*           TCAPLUS_API_GET_REQ,
*           TCAPLUS_API_LIST_GET_REQ,
*           TCAPLUS_API_LIST_GETALL_REQ
*
*  TCAPLUS_FLAG_FETCH_ONLY_IF_EXPIRED:
*      "Fetch only if expired" flag bit: Before starting a read operation, the user code sets the data expiration time through SetExpireTime(),
*      and set this flag. When the storage end detects that the record has been updated within the specified time, it will return the data.
*      Otherwise, it will not return the actual data, but only the error code of TcapErrCode::COMMON_INFO_DATA_NOT_MODIFIED.
*
*      After this flag bit is set in the request, the response should first be received through TcaplusServiceResponse::GetFlags() to find out
*      whether the TCAPLUS_FLAG_FETCH_ONLY_IF_EXPIRED flag was set when sending the request.
*
*      Only the following requests support setting this flag:
*           TCAPLUS_API_BATCH_GET_REQ
*
*  TCAPLUS_FLAG_ONLY_READ_FROM_SLAVE
*      After setting this flag, the read request will be directly sent to the Tcapsvr Slave node.
*      Tcapsvr Slave is usually relatively idle. Setting this flag helps to fully utilize Tcapsvr Slave resources.
*
*      Applicable scenarios:
*                              read requests that do not require high data timeliness,
*                              including all read requests for the generic table and list table, as well as batch get and traversal requests
*
*  TCAPLUS_FLAG_LIST_RESERVE_INDEX_HAVING_NO_ELEMENTS
*       After setting this flag, the index and version need to be retained when deleting the last element in the List table.
*       The ListDelete, ListDeleteBatch and ListDeleteAll operations set this flag when deleting the last element of the list table.
*       When writing a new List record, the version number will increase and not be reset to 1.
*
*      Applicable scenarios:
*                              app that needs to determine whether a table needs to retain index and version when deleting the last element.
*                              Mainly involves the use experience of the List table
*
*/
SetFlags(flag int32) int

/**
  @brief: clear the general flag bit of the request. Multiple values can be set at the same time through the "bit or" operation
  @param  [IN]  flag: value of the request flag bit
  @retval 0: setting successful
  @retval < 0 failed and returned the corresponding error code. Usually because it is not initialized.
  @note: for a list of valid flag bits and a detailed explanation, please refer to SetFlags()
*/
ClearFlags(flag int32) int

/**
  @brief: get the general flag bit of the request
  @return: return the general flag bit of the request
  @note: for a list of valid flag bits and a detailed explanation, please refer to SetFlags()
*/
GetFlags() int32

/**
  @brief: set the name list of the Value fields for getting or updating, that is, getting and updating part Value fields, which can be used for get, replace, and update operations.
  @param [IN] valueNameList: list of field names that need to be queried or updated
  @retval error: error code
  @note: when using this function to set a field name, the field name can only contain the value field name the key field name, not
              The refer field and array field should be set at the same time or not at the same time, otherwise there may be data confusion
**/
SetFieldNames(valueNameList []string) error

/**
@brief: set the user buffer, which is carried back by the response
@param [IN] userBuffer: user buffer
@retval error: error code
**/
SetUserBuff(userBuffer []byte) error

6. Method Description in Response Object

Note: Other methods of response object are not listed here, which means that this method is not required in the scenario of querying data. Misuse may result in errors.

/*
    @brief: get the result
    @retval int tcaplus api: user-defined error code 0 means the request was successful; non-0 means error codes, which can be got from terror.GetErrMsg(int)
*/
GetResult() int

/*
    @brief: get the result table Name
    @retval string: table name of the result message
*/
GetTableName() string

/*
    @brief: get the result appId
    @retval uint64: appId of the result message
*/
GetAppId() uint64

/*
    @brief: get the result zoneId
    @retval uint32: zoneId of the result message
*/
GetZoneId() uint32

/*
    @brief: get the result command word
    @retval int: result message command word, the response command word in the cmd package
*/
GetCmd() int

/*
    @brief: get the result asynchronous ID corresponding to the request
    @retval uint64: asynchronous ID of the result message, corresponding to the request
*/
GetAsyncId() uint64

/*
    @brief: get the number of result records in this response
    @retval int: the number of result records in this response
*/
GetRecordCount() int

/*
    @brief: get a record from the result
    @retval * record.Record: record pointer
    @retval error: error code
*/
FetchRecord() (*record.Record, error)

/*
    @brief: get the user buffer information in the response
    @retval []byte: user buffer binary, consistent with the buffer value in the request message
*/
GetUserBuffer() []byte

7. Method Description in Record Object

Note: Other methods of response object are not listed here, which means that this method is not required in the scenario of querying data. Misuse may result in errors.

• Common method of record:

/**
    @brief: get the record version number
    @retval: record version number
    @note: For the Generic operation, it means getting the version of the Record; whereas for the List operation, it means getting the version of the List in which the Record is located.
**/
func (r *Record) GetVersion() int32

• Record can be set and extracted based on TDR structure

 /**
@brief: set the record data based on the TDR description
@param [IN] data: record interface data based on the TDR description. The xml of tdr is a go structure generated by the tool, including a series of methods of the TdrTableSt interface
@retval error: error code
*/
func (r *Record) SetData(data TdrTableSt) error

/**
    @brief: get the record data based on the TDR description
    @param [IN] data: record interface data based on the TDR description. The xml of tdr is a go structure generated by the tool, including a series of methods of the TdrTableSt interface
    @retval error: error code
**/
func (r *Record) GetData(data TdrTableSt) error

• Record also supports the SetKey and SetValue interfaces for setting record fields and the GetKey and GetValue interfaces for fetching record fields. However, SetKey, SetValue, GetKey, and GetValue cannot be used with the SetData and GetData interfaces
  1. The data set by the SetKey SetValue interface can only be read through the GetKey and GetValue interfaces，When using the batch command for the SetKey SetValue interface, you should pay attention to that after the record setting is completed, you can call Pack () to package the records; SetData is one-time, and function calls will be automatically packaged. SetKey SetValue is not sure when the user has set the last field, so the user needs to call Pack () to package the records after setting kv
  2. The data set by the SetData interface can only be read through GetData

/**
  @brief: key field value setting
  @param  [in] name: field name, the maximum length of each field name is 32
  @param  [in] data: field value
  @retval error: error code
*/
func (r *Record) SetKeyInt8(name string, data int8) error
func (r *Record) SetKeyInt16(name string, data int16) error
func (r *Record) SetKeyInt32(name string, data int32) error
func (r *Record) SetKeyInt64(name string, data int64) error
func (r *Record) SetKeyFloat32(name string, data float32) error
func (r *Record) SetKeyFloat64(name string, data float64) error
func (r *Record) SetKeyStr(name string, data string) error
func (r *Record) SetKeyBlob(name string, data []byte) error

/**
  @brief: value field value setting
  @param  [in] name: field name, the maximum length of each field name is 32
  @param  [in] data: field value
  @retval error: error code
*/
func (r *Record) SetValueInt8(name string, data int8) error
func (r *Record) SetValueInt16(name string, data int16) error
func (r *Record) SetValueInt32(name string, data int32) error
func (r *Record) SetValueInt64(name string, data int64) error
func (r *Record) SetValueFloat32(name string, data float32) error
func (r *Record) SetValueFloat64(name string, data float64) error
func (r *Record) SetValueStr(name string, data string) error
func (r *Record) SetValueBlob(name string, data []byte) error

/**
  @brief: key field value getting
  @param  [in] name: field name, the maximum length of each field name is 32
  @retval data: field value
  @retval error: error code
*/
func (r *Record) GetKeyInt8(name string) (int8, error)
func (r *Record) GetKeyInt16(name string) (int16, error)
func (r *Record) GetKeyInt32(name string) (int32, error)
func (r *Record) GetKeyInt64(name string) (int64, error)
func (r *Record) GetKeyFloat32(name string) (float32, error)
func (r *Record) GetKeyFloat64(name string) (float64, error)
func (r *Record) GetKeyStr(name string) (string, error)
func (r *Record) GetKeyBlob(name string) ([]byte, error)

/**
  @brief: value field value getting
  @param  [in] name: field name, the maximum length of each field name is 32
  @retval data: field value
  @retval error: error code
*/
func (r *Record) GetValueInt8(name string) (int8, error)
func (r *Record) GetValueInt16(name string) (int16, error)
func (r *Record) GetValueInt32(name string) (int32, error)
func (r *Record) GetValueInt64(name string) (int64, error)
func (r *Record) GetValueFloat32(name string) (float32, error)
func (r *Record) GetValueFloat64(name string) (float64, error)
func (r *Record) GetValueStr(name string) (string, error)
func (r *Record) GetValueBlob(name string) ([]byte, error)

8. FAQ

For details, see Meaning and Handling of Error Codes.

8. Other Reference Documents

[[TDR Generic Table] [C++ SDK] Interface Description for Getting a Record](../../01C++_SDK/02Interface_Documents/01[Generic_Table]Get_a_Record.md

[[TDR Generic Table] [Java SDK] Interface Description for Getting a Record](../../02Java_SDK/02Interface_Documents/01[Generic_Table]Get_a_Record.md

[TDR Generic Table] [MySQL Protocol Compatibility Interface] Interface Description for Querying Local Index.