Skip to main content

Insert data

Overview​

This guide provides instructions to insert data into a multi-index table.

Procedure​

Complete the following steps to insert an user object in the datatable multi-index table:

1. Verify If The User Already Exists​

Use of the multi-index table iterator to find out if the user object already exists. The targeted user is searched based on its account name.

[[inery::action]] void multi_index_example::set( name user ) {
  // check if the user already exists
  auto itr = datatable.find(user.value);
}

2. Insert The User If Not Found In Table​

Use the emplace method to make the insertion if the user object is not already in the multi-index table. Otherwise print an informational message.

[[inery::action]] void multi_index_example::set( name user ) {
  // check if the user already exists
  auto itr = datatable.find(user.value);

+  if ( itr == datatable.end() ) {
+    datatable.emplace( _self, [&]( auto& u ) {
+      u.test_primary = user;
+      u.secondary = "second"_n;
+      u.datum = 0;
+    });
+  }
+  else {
+    printf("User already exists.");
+  }
}

Summary​

In conclusion, the above instructions show how to insert data in a multi-index table.

Last updated on