SymbolSelect HOW

Example from file: examples/demos/lowlevel/01_general_operations.go

The SymbolSelect() method is used to add or remove a symbol from Market Watch — the list of active instruments for which the gateway receives quotes. This is one of the key tools when working with symbols: it controls which instruments are active in the system.

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🧩 Code example

fmt.Println("\n4.4. SymbolSelect() - Add/remove symbol from Market Watch")

selectReq := &pb.SymbolSelectRequest{
    Symbol: cfg.TestSymbol,
    Select: true, // true = add to Market Watch, false = remove
}
selectData, err := account.SymbolSelect(ctx, selectReq)
if !helpers.PrintShortError(err, fmt.Sprintf("SymbolSelect(%s) failed", cfg.TestSymbol)) {
    fmt.Printf("  Symbol '%s' added to Market Watch: %v\n", cfg.TestSymbol, selectData.Success)
}

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🟢 Detailed Code Explanation

🔹 Creating the request

selectReq := &pb.SymbolSelectRequest{
    Symbol: cfg.TestSymbol,
    Select: true, // true = add to Market Watch, false = remove
}

Forms the SymbolSelectRequest request structure.

Field	Type	Description
Symbol	string	Symbol name, e.g. "EURUSD"
Select	bool	true — add, false — remove from Market Watch

The symbol value is taken from the configuration file appsettings.json (field test_symbol).

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🔹 Method call

selectData, err := account.SymbolSelect(ctx, selectReq)

Executes a gRPC request to the MetaTrader server.

• ctx — request context (with possible timeout);
• selectReq — structure with parameters;
• selectData — server response (protobuf structure);
• err — error if the request failed.

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🔹 Processing the result

if !helpers.PrintShortError(err, fmt.Sprintf("SymbolSelect(%s) failed", cfg.TestSymbol)) {
    fmt.Printf("  Symbol '%s' added to Market Watch: %v\n", cfg.TestSymbol, selectData.Success)
}

If there is no error, the result from selectData.Success is printed.

📘 Success = true means the operation was completed successfully.

Example output:

4.4. SymbolSelect() - Add/remove symbol from Market Watch
  Symbol 'EURUSD' added to Market Watch: true

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What the server returns

message SymbolSelectData {
  bool Success = 1; // true = operation completed successfully
}

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💡 Method purpose

SymbolSelect() controls the activity of symbols in the Market Watch list.

Action	Example call	Description
Add symbol	Select: true	Activates the symbol (enables quote stream)
Remove symbol	Select: false	Removes the symbol from Market Watch

If a symbol is not included in Market Watch, MetaTrader does not send quotes for it, and methods like SymbolInfoDouble() or streams (OnSymbolTick) will not return current data.

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⚙️ Usage example at gateway startup

symbol := cfg.TestSymbol

// 1. Check if symbol exists
existResp, _ := account.SymbolExist(ctx, &pb.SymbolExistRequest{Name: symbol})
if !existResp.Exists {
    log.Fatalf("Symbol %s not found on server", symbol)
}

// 2. Activate symbol in Market Watch
selectResp, _ := account.SymbolSelect(ctx, &pb.SymbolSelectRequest{
    Symbol: symbol,
    Select: true,
})
fmt.Printf("Symbol %s added to Market Watch: %v\n", symbol, selectResp.Success)

// 3. Check if we can receive quotes via stream
fmt.Println("Waiting for OnSymbolTick stream...")

---

🧠 In practice

SymbolSelect() is one of the first calls after connecting to the server, because it is what enables the quote stream for the required instruments.

Typical sequence during gateway initialization:

1. AccountSummary() — check account access.
2. SymbolExist() — make sure the symbol is available from the broker.
3. SymbolSelect() — add symbol to Market Watch.
4. OnSymbolTick() — start receiving quote stream.

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💬 In simple terms

SymbolSelect() is a switch for symbols. When you set Select = true, the gateway tells MetaTrader: "Add this instrument to Market Watch and start streaming quotes for it". If Select = false, the opposite — "remove the symbol from active ones and stop sending data".