1 files changed, 32 insertions, 2 deletions
diff --git a/src/contract.ts b/src/contract.ts
index 0c76571cc..3592e0e71 100644
--- a/src/contract.ts
+++ b/src/contract.ts
@@ -6,11 +6,13 @@ export class Contract implements Web3.ContractInstance {
     public address: string;
     public abi: Web3.ContractAbi;
     private contract: Web3.ContractInstance;
+    private defaults: Partial<Web3.TxData>;
     [name: string]: any;
-    constructor(web3ContractInstance: Web3.ContractInstance) {
+    constructor(web3ContractInstance: Web3.ContractInstance, defaults: Partial<Web3.TxData>) {
         this.contract = web3ContractInstance;
         this.address = web3ContractInstance.address;
         this.abi = web3ContractInstance.abi;
+        this.defaults = defaults;
         this.populateEvents();
         this.populateFunctions();
     }
@@ -18,11 +20,12 @@ export class Contract implements Web3.ContractInstance {
         const functionsAbi = _.filter(this.abi, abiPart => abiPart.type === 'function');
         _.forEach(functionsAbi, (functionAbi: Web3.MethodAbi) => {
             const cbStyleFunction = this.contract[functionAbi.name];
-            this[functionAbi.name] = promisify(cbStyleFunction, this.contract);
             if (functionAbi.constant) {
+                this[functionAbi.name] = promisify(cbStyleFunction, this.contract);
                 const cbStyleCallFunction = this.contract[functionAbi.name].call;
                 this[functionAbi.name].call = promisify(cbStyleCallFunction, this.contract);
             } else {
+                this[functionAbi.name] = this.promisifyWithDefaultParams(cbStyleFunction);
                 const cbStyleEstimateGasFunction = this.contract[functionAbi.name].estimateGas;
                 this[functionAbi.name].estimateGas =
                     promisify(cbStyleEstimateGasFunction, this.contract);
@@ -35,4 +38,31 @@ export class Contract implements Web3.ContractInstance {
             this[eventAbi.name] = this.contract[eventAbi.name];
         });
     }
+    private promisifyWithDefaultParams(fn: (...args: any[]) => void): (...args: any[]) => Promise<any> {
+        const promisifiedWithDefaultParams = (...args: any[]) => {
+            const promise = new Promise((resolve, reject) => {
+                const lastArg = args[args.length - 1];
+                let txData: Partial<Web3.TxData> = {};
+                if (_.isObject(lastArg) && !_.isArray(lastArg) && !lastArg.isBigNumber) {
+                    txData = args.pop();
+                }
+                txData = {
+                    ...txData,
+                    ...this.defaults,
+                };
+                const callback = (err: Error, data: any) => {
+                    if (_.isNull(err)) {
+                        resolve(data);
+                    } else {
+                        reject(err);
+                    }
+                };
+                args.push(txData);
+                args.push(callback);
+                fn.apply(this.contract, args);
+            });
+            return promise;
+        };
+        return promisifiedWithDefaultParams;
+    }
 }