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Runtime Error: "Assignment to Entry in Nil Map" Resolved
When attempting to create a slice of Maps, you may encounter the runtime error "assignment to entry in nil map." This error indicates that you are trying to access a nil Map value, which is not permitted.
Problem Statement
You are experiencing this error while building an array of Maps, each containing two keys: "Id" and "Investor." The attempted code is as follows:
<code class="go">for _, row := range rows { invs := make([]map[string]string, length) for i := 0; i < length; i++ { invs[i] = make(map[string]string) invs[i]["Id"] = inv_ids[i] invs[i]["Investor"] = inv_names[i] } }</code>
Resolution
To resolve this error, you should create a slice of Maps directly within the loop instead of creating nil Maps and assigning values to them. This can be achieved using composite literals:
<code class="go">for _, row := range rows { invs := make([]map[string]string, length) for i := 0; i < length; i++ { invs[i] = map[string]string{"Id": inv_ids[i], "Investor": inv_names[i]} } }</code>
Alternative Approach
Alternatively, you can use a struct to represent an investor:
<code class="go">type Investor struct { Id int Investor string } for _, row := range rows { invs := make([]Investor, length) for i := 0; i < length; i++ { invs[i] = Investor{ Id: inv_ids[i], Investor: inv_names[i], } } }</code>
Using a struct provides a cleaner and more structured representation of your data.
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