I need to store a vector of vector<std::string> as a field in a persistent class, how can I do this?

[juandent]

 class X  {
		using Row = std::vector<std::string>;
		using StringMatrix = std::vector<Row>;

		StringMatrix		m_matrix;
   }

[fnc12]

how would you store this in raw SQLite?

[juandent]

a table of strings with a foreign key number representing the external vector element

like this:

STRINGS_TABLE
string id

"Hello" 1
"Goodbye" 1
"Martin" 1
"Julie" 2
"Christian" 2

VECTOR TABLE
id vector_id

1 A
2 A
3 B

VECTOR OF VECTORS
vector id

A
B

is this correct?

[fnc12]

I don't think so. How would you solve this issue if you don't have sqlite_orm but only sqlite3 C library?

[juandent]

what is wrong with this proposal?

[fnc12]

Nothing wrong. But to answer this in terms of sqlite_orm one has to answer this in terms of SQLite first. sqlite_orm doesn't think instead of developer it just makes using SQLite easier. If the developer doesn't know how (s)he wants to store complex structure (vector of vectors in your case) in SQLite column no ORM can help

[juandent]

can you suggest what tables/relationships could work?

[juandent]

I am stuck here

[fnc12]

there are plenty of options and it depends on different conditions including developer's personal preferences. E.g. https://stackoverflow.com/questions/3005231/how-to-store-array-in-one-column-in-sqlite3 . Globally we have two ways:

1. move arrays and subarrays into dedicated table(s) like it is done in subentities example in our repo
2. encode/decode the whole array structure into single dynamic value (like blob or string) e.g. json, xml, invent your own an after that adopt this (en/de)coding into custom types binding just like it is done in enum binding examples in our repo