HDK: retrieving source chains

### query() (I) - Retrieve the source chain for the cell that's calling "query()" - Only way to retrieve private entries 

use hdk::prelude::*;

#[hdk_extern]
fn query_my_full_chain(_: ()) -> ExternResult<Vec<Record>> { 
  let filter = ChainQueryFilter::new(); // We'll see more options

  let my_full_chain: Vec<Record> = query(filter)?; // - Does not do any network call
                                                   // - Records are returned in ascendent
                                                   // order (from oldest to newest)

  Ok(my_full_chain)
}

query() (II)


use hdk::prelude::*;

#[hdk_entry_helper]
struct Comment {
  comment: String
}
#[hdk_entry_defs]
#[unit_enum(UnitEntryTypes)]
enum EntryTypes { 
  Comment(Comment),
}

#[hdk_extern]
fn query_my_comments(_: ()) -> ExternResult<Vec<Record>> { 
  let comment_entry_type: EntryType = UnitEntryTypes::Comment.try_into()?; // Generated with 
                                                                           // "#[unit_enum()]"
  let filter = ChainQueryFilter::new().entry_type(comment_entry_type); // Filter by the 
                                                                       // given entrytype
  let all_my_comments = query(filter)?; // Only the records which create or update comments
  Ok(all_my_comments)
}

#[hdk_extern]
fn query_all_links_i_created(_: ()) -> ExternResult<Vec<Record>> { 
  let filter = ChainQueryFilter::new().action_type(ActionType::CreateLink); // May be any kind
                                                                            // of action
  let all_links_i_created = query(filter)?; // Only the records whose action 
                                            // is of the "CreateLink" variant
  Ok(all_links_i_created)
}
### get_agent_activity() - Retrieve the source chain actions for a given agent - All actions are public in the DHT - Doesn't return entries 

use hdk::prelude::*;

#[hdk_extern]
fn get_comments_created_by(author: AgentPubKey) -> ExternResult<Vec<ActionHash>> { 
  let filter = ChainQueryFilter::new(); // Same options as "query"

  let agent_activity = get_agent_activity(
    author,
    filter,
    ActivityRequest::Full // - "ActivityRequest" can be: 
                          //   - "Full": request the list of action hashes for the full chain
                          //   - "Status": request only the status of the chain
  )?;
}

That's it!