[help] load a target from multiple store

[dsolito]

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Description

Hello, I try to load a target from multiple store (stores are located in the stores folder).
To do this I wrote a function that I map on a vector of paths (store paths).
Everythink is OK until I try to to set the file as argument to my function.

This works :

dirs <- list.dirs("../stores", full.names = TRUE, recursive = FALSE)

extract <- \(store) {

    with(tar_config_set(store = store), {
        safe_load <- safely(tar_read)
        data <- safe_load("my_obj")$result
        if(is.null(data)) {
            NULL
        } else {
            return(data)
        }
    })

}


data <- map(dirs, ~ extract(store = .x)) |> list_rbind()

and this doesn't

dirs <- list.dirs("../stores", full.names = TRUE, recursive = FALSE)

extract <- \(file, store) {

    with(tar_config_set(store = store), {
        safe_load <- safely(tar_read)
        data <- safe_load(file)$result
        if(is.null(data)) {
            NULL
        } else {
            return(data)
        }
    })

}


data <- map(dirs, ~ extract(file = "my_obj" ,store = .x)) |> list_rbind()

Is it a problem with the with_ function?
Any ideas how to do it?

Thank you!

[wlandau]

Hard to say what might be wrong, but you might want to use tar_read_raw() here instead of tar_read() because the former avoids non-standard evaluation. Also, I recommend passing the data store path to the store of tar_read_raw().

[dsolito]

Oh God! I didn't check the raw version! Thank you. The solution was to evaluate the call, but it's now unnecessary.

extract <- \(file, store) {
    safe_read <- safely(function(name, store) {
        eval(call("tar_read", as.name(name), store = store))
    })
    
    data <- safe_read(target_name, store = store)$result
    
    if(is.null(data)) {
        NULL
    } else {
      ...
    }
}