Historical Message

Overview
The API for pulling historical messages is in the TencentImSDKPlugin.v2TIMManager.getMessageManager() class.
In addition to the support for pulling historical one-to-one and group messages, an advanced API is provided to pull messages by sequence, start point, or time range.
Both local and cloud historical messages can be pulled.
Note: 
 When historical messages are pulled from the cloud and a network exception is detected, the SDK will return the locally stored historical messages.
Locally stored historical messages are not subject to time limits, but those stored in the cloud are subject to the following time limits:
Free edition: The free storage period is 7 days and cannot be extended.
Pro edition: The free storage period is 7 days and can be extended.
Ultimate edition: The free storage period is 30 days and can be extended.
Note: 
It is a value-added service to extend the storage period of historical messages. You can log in to the Chat console to modify relevant configuration. For information about billing, see Value-added Service Pricing.
Rich media messages (such as images, files, and audios) have the same storage periods as historical messages.
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Pulling Historical One-to-One Messages
Call the getC2CHistoryMessageList API (details) to get historical one-to-one messages.
When the network is normal, the latest cloud data will be pulled; when it is abnormal, the SDK will return the locally stored historical messages.
If you want to pull only local historical messages, see Advanced API.
This API supports pulling by page. For more information, see Pulling by page.
Sample code:
// Pull historical one-to-one messages
// Set `lastMsgID` to `null` for the first pull
// `lastMsgID` can be the ID of the last message in the returned message list for the second pull.
TencentImSDKPlugin.v2TIMManager.getMessageManager().getC2CHistoryMessageList(
        userID: "userId",
        count: 10,
        lastMsgID: null,
);
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Pulling Historical Group Messages
Call the getGroupHistoryMessageList API (details) to get historical group messages.
When the network is normal, the latest cloud data will be pulled; when it is abnormal, the SDK will return the locally stored historical messages.
If you want to pull only local historical messages, see Advanced API.
This API supports pulling by page. For more information, see Pulling by page.
Caution: 
Only the historical messages of meeting groups (Meeting) can be pulled. For more information on group message limits, see Group System.
This API does not apply to audio-video groups (AVChatRoom), as their messages are not stored on the cloud or in the local database.
Sample code:
// Pull historical group messages
// Set `lastMsgID` to `null` for the first pull
// `lastMsgID` can be the ID of the last message in the returned message list for the second pull.
TencentImSDKPlugin.v2TIMManager
      .getMessageManager()
      .getGroupHistoryMessageList(
        groupID: "groupID",
        count: 10,
        lastMsgID: null,
      );
Advanced Features
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Advanced API
If the ordinary APIs above cannot meet your needs to pull historical messages, you can use the advanced API getHistoryMessageList (details).
In addition to pulling historical one-to-one and group messages, this API supports the following advanced features:
Set the source for message pull: pull from the local database or the cloud
Specify the sequence for message pull: pull in reverse chronological order or in chronological order
Specify the message type for local pull: text, image, audio, video, file, emoji, group tip, combined, or custom message
API prototype:
    // Pull historical one-to-one messages
    // Set `lastMsgID` to `null` for the first pull
    // `lastMsgID` can be the ID of the last message in the returned message list for the second pull.
    V2TimValueCallback<List<V2TimMessage>> getHistoryMessageListRes =
        await TencentImSDKPlugin.v2TIMManager
            .getMessageManager()
            .getHistoryMessageList(
      getType: HistoryMsgGetTypeEnum.V2TIM_GET_LOCAL_OLDER_MSG, // Source and sequence of the message pull
      userID: "userID", // To pull one-to-one messages with a certain user, you need to specify only the `userID`.
      groupID: "groupID", // To pull group messages from a certain group, you need to specify only the `groupID`.
      count: 10, // Number of messages pulled
      lastMsgID: null, // ID of the first message for pulling
      // This field can be used only for group chats.
      // If `lastMsgSeq` is set as the start point for message, the message will be included in the returned message list.
      // If both `lastMsg` and `lastMsgSeq` are specified, the SDK will use `lastMsg`.
      // If neither `lastMsg` nor `lastMsgSeq` is specified, the start point for pull will be determined based on whether the `getTimeBegin` is set. If yes, the set range will be used as the start point; if no, the latest message will be used as the start point.
      lastMsgSeq: -1,
      messageTypeList: [], // Used to filter historical message information attributes. If this field is left empty, all attributes will be pulled.
    );
    if (getHistoryMessageListRes.code == 0) {
      // Obtained successfully
    }
Parameters:
Parameter
Description
Valid for One-to-One Chat
Valid for Group Chat
Required
Remarks
getType
Source and sequence of the message pull, which can be set to local/cloud and reverse chronological order/chronological order respectively.
YES
YES
YES
When the pull source is set to the cloud, the local message list and cloud message list will be combined and returned. If there is no network connection, the local message list will be returned.
userID
The specified user ID with which to pull historical one-to-one messages
YES
NO
NO
To pull one-to-one messages, you need to specify only the userID.
groupID
The specified group ID with which to pull historical group messages
NO
YES
NO
To pull group messages, you need to specify only the groupID.
count
Number of messages per pull
YES
YES
YES
We recommend you set it to 20 for iOS/Android clients; otherwise, the pull speed may be affected. For web clients, the maximum value allowed is 15.
lastMsgID
ID of the last message, indicating the message starting from which to pull historical messages
YES
YES
NO
1. It can be used for both one-to-one and group chats.
2. If it is set as the start point for the message pull, the message will not be included in the returned message list.
3. If it is left empty, the latest message in the conversation will be used as the start point for pull.
lastMsgSeq
seq of the last message, indicating the message starting from which to pull historical messages
NO
YES
NO
1. It can be used only for group chats.
2. If it is set as the start point for the message pull, the message will be included in the returned message list.
3. If both lastMsg and lastMsgSeq are specified, the SDK will use lastMsg.
4. If neither lastMsg nor lastMsgSeq is specified, the start point for pull will be determined based on whether the getTimeBegin is set. If yes, the set range will be used as the start point; if no, the latest message will be used as the start point.
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Pulling by page
Historical one-to-one message pull, historical group message pull, and pull via the advanced API can all be paged by using lastMsg and count.
Pulling by page can be implemented by using lastMsg and count. For the first pull, lastMsg can be left empty, which indicates that the last message in the returned message list will be used as the lastMsg to pull data of the next page.
When lastMsg is left empty, the SDK will return historical messages starting from the latest message by default.
When lastMsg is set, it is not included in the returned message list.
The returned message list displays messages in reverse chronological order.
Note: 
1. To avoid affecting the speed of pulling historical messages, we recommend you set count to 20 for pagination.
2. We recommend you not use lastMsgSeq for the subsequent pull, as the corresponding message will be included in the returned message list.
Pulling only local messages
Set getType to pull only local messages:
When getType is set to V2TIM_GET_LOCAL_OLDER_MSG, locally stored messages will be pulled in reverse chronological order.
When getType is set to V2TIM_GET_LOCAL_NEWER_MSG, locally stored messages will be pulled in chronological order.
The following sample code demonstrates the process of pulling 20 one-to-one messages from the local database in reverse chronological order, starting from the latest message:
TencentImSDKPlugin.v2TIMManager.getMessageManager().getHistoryMessageList(
        count: 10,
        getType: HistoryMsgGetTypeEnum.V2TIM_GET_LOCAL_OLDER_MSG,
        userID: "userID",
);
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Pulling messages after redirecting to the group @ message
After a user receives a group @ message in a group conversation, the user generally needs to click the @ bar to go to the message and pull the neighboring messages for display.
As the group @ message also needs to be displayed, you can set its sequence as the lastMsgSeq and use the advanced API to pull messages.
The following sample code demonstrates the process of clicking the @ bar, redirecting to the group @ message, and pulling the first 20 messages earlier and later than that message for display:
// Get the `sequence` of the group @ message
int atSequence = 1081;
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// Pull the group @ message and earlier messages
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  TencentImSDKPlugin.v2TIMManager.getMessageManager().getHistoryMessageList(
        count: 20, // Pull 20 messages
        getType: HistoryMsgGetTypeEnum.V2TIM_GET_CLOUD_OLDER_MSG, // Pull messages earlier than the group @ message
        lastMsgSeq: atSequence,// Start the pull from the group @ message, which is included in the pull list
        groupID: "groupID" // Pull group messages
      );
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// Pull messages later than the group @ message
TencentImSDKPlugin.v2TIMManager.getMessageManager().getHistoryMessageList(
        count: 20, // Pull 20 messages
        getType: HistoryMsgGetTypeEnum.V2TIM_GET_CLOUD_NEWER_MSG, // Pull messages later than the group @ message
        lastMsgSeq: atSequence,// Start the pull from the group @ message, which is included in the pull list
        groupID: "groupID" // Pull group messages
      );
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FAQs
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1. What should I do if "total count of request cloud message exceed max limit" is displayed in the log when I am pulling historical messages?
Currently, the SDK policy is as described below:
1. When getType is set to pull cloud historical messages and the number of messages to be pulled is set to x, the SDK will pull x messages from the cloud.
2. The SDK will filter out invalid messages, such as deleted messages and those irrelevant to the current user.
3. If there are too many invalid historical messages in the cloud, the SDK will perform multiple paged pulls.
To ensure the system stability and robustness, the SDK will perform up to three automatic paged pulls. After this limit is exceeded, the "total count of request cloud message exceed max limit" message will be displayed in the log.
To minimize the impact of such a limit mechanism on the business layer, you can take the following measures to reduce invalid messages:
You can use online messages, that is, set onlineUserOnly to YES/true when sending messages.
For group messages, you can use targeted group messages to specify the receiver.
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2. What should I do if messages are "lost" during cloud historical message pull?
When getType is set to pull cloud historical messages and the number of messages is count, the SDK will perform the following operations:
1. Pull count messages from the local database.
2. Pull count messages from the cloud and filter out invalid messages such as deleted messages. If the number is smaller than count, the paged pull will be triggered.
3. Combine local and cloud messages and update information such as the message status.
4. Return count messages from the combined message list.
Generally speaking, message loss indicates that too many invalid messages are pulled in step 2, which triggers the limit mechanism in question 1 and leads to an insufficient number of messages actually pulled from the cloud.
We recommend you fix this issue as instructed in question 1.
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3. What should I do if group member information such as the group name card is not updated in real time when historical messages are pulled?
When messages are generated, the SDK will update the current group member information such as the group name card and role and store it in the local database.
When historical group messages are pulled, the SDK will directly return the group member information when the messages were generated and will not update it in real time.
If you want to get the latest group member information, you can use the getGroupMembersInfo API (details).
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4. What should I do if I get a lag while pulling historical messages?
The SDK has been optimized for message pull. If a lag occurs, you can reduce the number of pulled messages (count). 

Overview
Pulling Historical One-to-One Messages
Pulling Historical Group Messages
Advanced Features
FAQs

Parameter	Description	Valid for One-to-One Chat	Valid for Group Chat	Required	Remarks
getType	Source and sequence of the message pull, which can be set to local/cloud and reverse chronological order/chronological order respectively.	YES	YES	YES	When the pull source is set to the cloud, the local message list and cloud message list will be combined and returned. If there is no network connection, the local message list will be returned.
userID	The specified user ID with which to pull historical one-to-one messages	YES	NO	NO	To pull one-to-one messages, you need to specify only the `userID`.
groupID	The specified group ID with which to pull historical group messages	NO	YES	NO	To pull group messages, you need to specify only the `groupID`.
count	Number of messages per pull	YES	YES	YES	We recommend you set it to `20` for iOS/Android clients; otherwise, the pull speed may be affected. For web clients, the maximum value allowed is `15`.
lastMsgID	ID of the last message, indicating the message starting from which to pull historical messages	YES	YES	NO	1. It can be used for both one-to-one and group chats. 2. If it is set as the start point for the message pull, the message will not be included in the returned message list. 3. If it is left empty, the latest message in the conversation will be used as the start point for pull.
lastMsgSeq	`seq` of the last message, indicating the message starting from which to pull historical messages	NO	YES	NO	1. It can be used only for group chats. 2. If it is set as the start point for the message pull, the message will be included in the returned message list. 3. If both lastMsg and lastMsgSeq are specified, the SDK will use lastMsg. 4. If neither lastMsg nor lastMsgSeq is specified, the start point for pull will be determined based on whether the getTimeBegin is set. If yes, the set range will be used as the start point; if no, the latest message will be used as the start point.