Add type for second getblockfilter param

btcjson/chainsvrcmds.go

@@ -163,18 +163,27 @@ func NewGetBlockCountCmd() *GetBlockCountCmd {
 	return &GetBlockCountCmd{}
 }
 
+// FilterTypeName defines the type used in the getblockfilter JSON-RPC command for the
+// filter type field.
+type FilterTypeName string
+
+const (
+	// Basic is the basic filter type defined in BIP0158.
+	FilterTypeBasic FilterTypeName = "basic"
+)
+
 // GetBlockFilterCmd defines the getblockfilter JSON-RPC command.
 type GetBlockFilterCmd struct {
-	BlockHash  string  // The hash of the block
-	FilterType *string // The type name of the filter, default=basic
+	BlockHash  string          // The hash of the block
+	FilterType *FilterTypeName // The type name of the filter, default=basic
 }
 
 // NewGetBlockFilterCmd returns a new instance which can be used to issue a
 // getblockfilter JSON-RPC command.
 //
 // The parameters which are pointers indicate they are optional.  Passing nil
 // for optional parameters will use the default value.
-func NewGetBlockFilterCmd(blockHash string, filterType *string) *GetBlockFilterCmd {
+func NewGetBlockFilterCmd(blockHash string, filterType *FilterTypeName) *GetBlockFilterCmd {
 	return &GetBlockFilterCmd{
 		BlockHash:  blockHash,
 		FilterType: filterType,

rpcclient/chain.go

@@ -388,15 +388,15 @@ func (r FutureGetBlockFilterResult) Receive() (*btcjson.GetBlockFilterResult, er
 // returned instance.
 //
 // See GetBlockFilter for the blocking version and more details.
-func (c *Client) GetBlockFilterAsync(blockHash chainhash.Hash, filterType *string) FutureGetBlockFilterResult {
+func (c *Client) GetBlockFilterAsync(blockHash chainhash.Hash, filterType *btcjson.FilterTypeName) FutureGetBlockFilterResult {
 	hash := blockHash.String()
 
 	cmd := btcjson.NewGetBlockFilterCmd(hash, filterType)
 	return c.sendCmd(cmd)
 }
 
-// GetBlockFilter retrieves a BIP 157 content filter for a particular block.
-func (c *Client) GetBlockFilter(blockHash chainhash.Hash, filterType *string) (*btcjson.GetBlockFilterResult, error) {
+// GetBlockFilter retrieves a BIP0157 content filter for a particular block.
+func (c *Client) GetBlockFilter(blockHash chainhash.Hash, filterType *btcjson.FilterTypeName) (*btcjson.GetBlockFilterResult, error) {
 	return c.GetBlockFilterAsync(blockHash, filterType).Receive()
 }