How do I make this Go code more DRY?

Question

I'm implementing a Go wrapper for a REST API. It basically parses JSON and should return the appropriate struct type. I find myself doing a lot of this:

// GetBlueprintDetails returns details about a blueprint
func (c *Client) GetBlueprintDetails(projectID string, blueprintID string) (*BlueprintDetails, *APIError) {
    path := fmt.Sprintf("projects/%s/blueprints/%s", projectID, blueprintID)
    res, err := c.Request("GET", path, nil, nil)
    if err != nil {
        return nil, err
    }
    var ret BlueprintDetails
    e := json.Unmarshal(res.Body, &ret)
    if e != nil {
        return nil, &APIError{Error: &e}
    }
    return &ret, nil
}

// GetProjects returns a list of projects for the user
func (c *Client) GetProjects() (*[]Project, *APIError) {
    res, err := c.Request("GET", "projects", nil, nil)
    if err != nil {
        return nil, err
    }
    var ret []Project
    e := json.Unmarshal(res.Body, &ret)
    if e != nil {
        return nil, &APIError{Error: &e}
    }
    return &ret, nil
}

The only difference between the two functions is the type of the unmarshaled struct basically. I know there are no generic in Go, but there has to be a pattern to make this more DRY.

Any ideas?

Answer 1

You may create a MakeRequest function that does the http request part and unmarshal the json to struct

Here is how you may do it, have a look at the MakeRequest function

// GetBlueprintDetails returns details about a blueprint
func (c *Client) GetBlueprintDetails(projectID string, blueprintID string) (*BlueprintDetails, *APIError) {
    path := fmt.Sprintf("projects/%s/blueprints/%s", projectID, blueprintID)
    bluePrintDetails = new(BlueprintDetails)
    err := c.MakeRequest("GET", path, bluePrintDetails)
    return bluePrintDetails, err
}

// GetProjects returns a list of projects for the user
func (c *Client) GetProjects() (*[]Project, *APIError) {
    projects = make([]Project, 0)
    err := c.MakeRequest("GET", "project", &projects)
    return &projects, err
}

func (c *Client) MakeRequest(method string, path string, response interface{}) *APIError {
    res, err := c.Request(method, path, nil, nil)
    if err != nil {
        return nil, err
    }
    e := json.Unmarshal(res.Body, response)
    if e != nil {
        return &APIError{Error: &e}
    }
    return nil
}