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1

In a html.erb (called show.html.erb) that is displaying a post, I am adding a link_to in order to edit the post. There is only one line of change that I did

does not work

<%= link_to("edit", "/posts/:id/edit") %>

works

<%= link_to("edit", "/posts/#@post.id/edit") %>

For routes.rb, I have

get "posts/:id/edit => "posts#edit"

In the Controller,

 def edit
 @post = Post.find_by(id: params[:id])
 end

in the edit.html.erb, I have

<textarea><%= @post.content %></textarea>
<input type="submit" value="save">

NoMethodError in Posts#edit

Showing /home/progate/tweet_app/app/views/posts/edit.html.erb where line #6 raised:

undefined method `content' for nil:NilClass

With my limited knowledge of Rails, I understand that because in the controller, I am defining @post with find_by, I would imagine that link URL can be using symbol :id.

But it seems like that is not the case.

Why does link_to with :id not work?

ruby-on-rails

share|improve this question

asked Mar 24 at 21:08

Shintaro TakechiShintaro Takechi

369319

add a comment | 

1

In a html.erb (called show.html.erb) that is displaying a post, I am adding a link_to in order to edit the post. There is only one line of change that I did

does not work

<%= link_to("edit", "/posts/:id/edit") %>

works

<%= link_to("edit", "/posts/#@post.id/edit") %>

For routes.rb, I have

get "posts/:id/edit => "posts#edit"

In the Controller,

 def edit
 @post = Post.find_by(id: params[:id])
 end

in the edit.html.erb, I have

<textarea><%= @post.content %></textarea>
<input type="submit" value="save">

NoMethodError in Posts#edit

Showing /home/progate/tweet_app/app/views/posts/edit.html.erb where line #6 raised:

undefined method `content' for nil:NilClass

With my limited knowledge of Rails, I understand that because in the controller, I am defining @post with find_by, I would imagine that link URL can be using symbol :id.

But it seems like that is not the case.

Why does link_to with :id not work?

ruby-on-rails

share|improve this question

asked Mar 24 at 21:08

Shintaro TakechiShintaro Takechi

369319

add a comment | 

In a html.erb (called show.html.erb) that is displaying a post, I am adding a link_to in order to edit the post. There is only one line of change that I did

does not work

<%= link_to("edit", "/posts/:id/edit") %>

works

<%= link_to("edit", "/posts/#@post.id/edit") %>

For routes.rb, I have

get "posts/:id/edit => "posts#edit"

In the Controller,

 def edit
 @post = Post.find_by(id: params[:id])
 end

in the edit.html.erb, I have

<textarea><%= @post.content %></textarea>
<input type="submit" value="save">

NoMethodError in Posts#edit

Showing /home/progate/tweet_app/app/views/posts/edit.html.erb where line #6 raised:

undefined method `content' for nil:NilClass

With my limited knowledge of Rails, I understand that because in the controller, I am defining @post with find_by, I would imagine that link URL can be using symbol :id.

But it seems like that is not the case.

Why does link_to with :id not work?

ruby-on-rails

share|improve this question

asked Mar 24 at 21:08

Shintaro TakechiShintaro Takechi

369319

<%= link_to("edit", "/posts/:id/edit") %>

<%= link_to("edit", "/posts/#@post.id/edit") %>

get "posts/:id/edit => "posts#edit"

 def edit
 @post = Post.find_by(id: params[:id])
 end

<textarea><%= @post.content %></textarea>
<input type="submit" value="save">

share|improve this question

asked Mar 24 at 21:08

Shintaro TakechiShintaro Takechi

369319

share|improve this question

asked Mar 24 at 21:08

Shintaro TakechiShintaro Takechi

369319

asked Mar 24 at 21:08

Shintaro TakechiShintaro Takechi

369319

asked Mar 24 at 21:08

Shintaro TakechiShintaro Takechi

369319

1 Answer
1

active

oldest

votes

1

Short Answer:
Because the first 'link_to' is literally taking you to 'www.yoursite.com/posts/:id/edit' while the second one uses something called "String Interpolation" to replace the # block with the ruby code inside of it. In this case, the proper Post ID taking you to 'www.yoursite.com/posts/1/edit' or whatever the id of the post is.

Long Answer:
When you created the route

get "posts/:id/edit => "posts#edit"

That ":id" is just a stand in for something else and becomes a parameter, so when you make a link_to using string literals ("/posts/:id/edit") it takes you to edit a post with an ID of ":id";

 <%= link_to("edit", "/posts/:id/edit") %>

The second one works because it uses String Interpolation to inject the ID of the post into the link_to;

 <%= link_to("edit", "/posts/#@post.id/edit") %>

becomes;

<%= link_to("edit", "/posts/1/edit") %>

and then finds a post with an ID of 1 and edits it.

The reason you are getting the error is because in the first one with no interpolation, it's not finding a Post, so post.content can't work since post is nil.

share|improve this answer

answered Mar 24 at 21:38

srngsrng

1667

add a comment | 

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1

Short Answer:
Because the first 'link_to' is literally taking you to 'www.yoursite.com/posts/:id/edit' while the second one uses something called "String Interpolation" to replace the # block with the ruby code inside of it. In this case, the proper Post ID taking you to 'www.yoursite.com/posts/1/edit' or whatever the id of the post is.

Long Answer:
When you created the route

get "posts/:id/edit => "posts#edit"

That ":id" is just a stand in for something else and becomes a parameter, so when you make a link_to using string literals ("/posts/:id/edit") it takes you to edit a post with an ID of ":id";

 <%= link_to("edit", "/posts/:id/edit") %>

The second one works because it uses String Interpolation to inject the ID of the post into the link_to;

 <%= link_to("edit", "/posts/#@post.id/edit") %>

becomes;

<%= link_to("edit", "/posts/1/edit") %>

and then finds a post with an ID of 1 and edits it.

The reason you are getting the error is because in the first one with no interpolation, it's not finding a Post, so post.content can't work since post is nil.

share|improve this answer

answered Mar 24 at 21:38

srngsrng

1667

add a comment | 

1

Short Answer:
Because the first 'link_to' is literally taking you to 'www.yoursite.com/posts/:id/edit' while the second one uses something called "String Interpolation" to replace the # block with the ruby code inside of it. In this case, the proper Post ID taking you to 'www.yoursite.com/posts/1/edit' or whatever the id of the post is.

Long Answer:
When you created the route

get "posts/:id/edit => "posts#edit"

That ":id" is just a stand in for something else and becomes a parameter, so when you make a link_to using string literals ("/posts/:id/edit") it takes you to edit a post with an ID of ":id";

 <%= link_to("edit", "/posts/:id/edit") %>

The second one works because it uses String Interpolation to inject the ID of the post into the link_to;

 <%= link_to("edit", "/posts/#@post.id/edit") %>

becomes;

<%= link_to("edit", "/posts/1/edit") %>

and then finds a post with an ID of 1 and edits it.

The reason you are getting the error is because in the first one with no interpolation, it's not finding a Post, so post.content can't work since post is nil.

share|improve this answer

answered Mar 24 at 21:38

srngsrng

1667

add a comment | 

Short Answer:
Because the first 'link_to' is literally taking you to 'www.yoursite.com/posts/:id/edit' while the second one uses something called "String Interpolation" to replace the # block with the ruby code inside of it. In this case, the proper Post ID taking you to 'www.yoursite.com/posts/1/edit' or whatever the id of the post is.

Long Answer:
When you created the route

get "posts/:id/edit => "posts#edit"

That ":id" is just a stand in for something else and becomes a parameter, so when you make a link_to using string literals ("/posts/:id/edit") it takes you to edit a post with an ID of ":id";

 <%= link_to("edit", "/posts/:id/edit") %>

The second one works because it uses String Interpolation to inject the ID of the post into the link_to;

 <%= link_to("edit", "/posts/#@post.id/edit") %>

becomes;

<%= link_to("edit", "/posts/1/edit") %>

and then finds a post with an ID of 1 and edits it.

The reason you are getting the error is because in the first one with no interpolation, it's not finding a Post, so post.content can't work since post is nil.

share|improve this answer

answered Mar 24 at 21:38

srngsrng

1667

get "posts/:id/edit => "posts#edit"

 <%= link_to("edit", "/posts/:id/edit") %>

 <%= link_to("edit", "/posts/#@post.id/edit") %>

<%= link_to("edit", "/posts/1/edit") %>

share|improve this answer

answered Mar 24 at 21:38

srngsrng

1667

answered Mar 24 at 21:38

srngsrng

1667

answered Mar 24 at 21:38

srngsrng

1667